Code re-work: Advanced OpenGL

src/4.advanced_opengl/1.1.depth_testing/depth_testing.cpp

@@ -183,7 +183,7 @@ int main()
 
         // render
         // ------
-        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
         shader.use();

src/4.advanced_opengl/1.2.depth_testing_view/depth_testing_view.cpp

@@ -183,7 +183,7 @@ int main()
 
         // render
         // ------
-        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
         shader.use();

src/4.advanced_opengl/2.stencil_testing/stencil_testing.cpp

@@ -187,7 +187,7 @@ int main()
 
         // render
         // ------
-        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); // don't forget to clear the stencil buffer!
 
         // set uniforms

src/4.advanced_opengl/3.1.blending_discard/blending_discard.cpp

@@ -70,7 +70,6 @@ int main()
     // configure global opengl state
     // -----------------------------
     glEnable(GL_DEPTH_TEST);
-    glDepthFunc(GL_ALWAYS); // always pass the depth test (same effect as glDisable(GL_DEPTH_TEST))
 
      // build and compile shaders
     // -------------------------
@@ -183,7 +182,7 @@ int main()
 
         // render
         // ------
-        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 

src/4.advanced_opengl/3.2.blending_sort/blending_sorted.cpp

@@ -70,7 +70,6 @@ int main()
     // configure global opengl state
     // -----------------------------
     glEnable(GL_DEPTH_TEST);
-    glDepthFunc(GL_ALWAYS); // always pass the depth test (same effect as glDisable(GL_DEPTH_TEST))
 
     // build and compile shaders
     // -------------------------
@@ -183,7 +182,7 @@ int main()
 
         // render
         // ------
-        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 

src/4.advanced_opengl/5.1.framebuffers/5.1.framebuffers.fs

@@ -1,11 +1,11 @@
 #version 330 core
-in vec2 TexCoords;
+out vec4 FragColor;
 
-out vec4 color;
+in vec2 TexCoords;
 
 uniform sampler2D texture1;
 
 void main()
 {    
-    color = texture(texture1, TexCoords);
+    FragColor = texture(texture1, TexCoords);
 }

src/4.advanced_opengl/5.1.framebuffers/5.1.framebuffers.vs

@@ -1,6 +1,6 @@
 #version 330 core
-layout (location = 0) in vec3 position;
+layout (location = 0) in vec3 aPos;
-layout (location = 1) in vec2 texCoords;
+layout (location = 1) in vec2 aTexCoords;
 
 out vec2 TexCoords;
 
@@ -10,6 +10,6 @@ uniform mat4 projection;
 
 void main()
 {
-    gl_Position = projection * view * model * vec4(position, 1.0f);
+    TexCoords = aTexCoords;    
-    TexCoords = texCoords;
+    gl_Position = projection * view * model * vec4(aPos, 1.0);
 }

src/4.advanced_opengl/5.1.framebuffers/5.1.framebuffers_screen.fs

@@ -1,40 +1,12 @@
 #version 330 core
-in vec2 TexCoords;
+out vec4 FragColor;
 
-out vec4 color;
+in vec2 TexCoords;
 
 uniform sampler2D screenTexture;
 
-const float offset = 1.0 / 300;  
-
 void main()
 {
-    vec2 offsets[9] = vec2[](
+    vec3 col = texture(screenTexture, TexCoords).rgb;
-        vec2(-offset, offset),  // top-left
+    FragColor = vec4(col, 1.0);
-        vec2(0.0f,    offset),  // top-center
-        vec2(offset,  offset),  // top-right
-        vec2(-offset, 0.0f),    // center-left
-        vec2(0.0f,    0.0f),    // center-center
-        vec2(offset,  0.0f),    // center-right
-        vec2(-offset, -offset), // bottom-left
-        vec2(0.0f,    -offset), // bottom-center
-        vec2(offset,  -offset)  // bottom-right    
-    );
-
-    float kernel[9] = float[](
-        -1, -1, -1,
-        -1,  9, -1,
-        -1, -1, -1
-    );
-    
-    vec3 sampleTex[9];
-    for(int i = 0; i < 9; i++)
-    {
-        sampleTex[i] = vec3(texture(screenTexture, TexCoords.st + offsets[i]));
-    }
-    vec3 col;
-    for(int i = 0; i < 9; i++)
-        col += sampleTex[i] * kernel[i];
-    
-    color = vec4(col, 1.0);
 } 

src/4.advanced_opengl/5.1.framebuffers/5.1.framebuffers_screen.vs

@@ -1,11 +1,11 @@
 #version 330 core
-layout (location = 0) in vec2 position;
+layout (location = 0) in vec2 aPos;
-layout (location = 1) in vec2 texCoords;
+layout (location = 1) in vec2 aTexCoords;
 
 out vec2 TexCoords;
 
 void main()
 {
-    gl_Position = vec4(position.x, position.y, 0.0f, 1.0f); 
+    TexCoords = aTexCoords;
-    TexCoords = texCoords;
+    gl_Position = vec4(aPos.x, aPos.y, 0.0, 1.0); 
 }  

src/4.advanced_opengl/5.1.framebuffers/framebuffers.cpp

@@ -1,87 +1,85 @@
-// Std. Includes
+#include <glad/glad.h>
-#include <string>
-#include <algorithm>
-using namespace std;
-
-// GLEW
-#define GLEW_STATIC
-#include <GL/glew.h>
-
-// GLFW
 #include <GLFW/glfw3.h>
+#include <stb_image.h>
 
-// GL includes
-#include <learnopengl/shader.h>
-#include <learnopengl/camera.h>
-
-// GLM Mathemtics
 #include <glm/glm.hpp>
 #include <glm/gtc/matrix_transform.hpp>
 #include <glm/gtc/type_ptr.hpp>
 
-// Other Libs
-#include <SOIL.h>
 #include <learnopengl/filesystem.h>
+#include <learnopengl/shader_m.h>
+#include <learnopengl/camera.h>
+#include <learnopengl/model.h>
 
-// Properties
+#include <iostream>
-GLuint screenWidth = 800, screenHeight = 600;
 
-// Function prototypes
+void framebuffer_size_callback(GLFWwindow* window, int width, int height);
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
-void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
 void mouse_callback(GLFWwindow* window, double xpos, double ypos);
-void Do_Movement();
+void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
-GLuint loadTexture(GLchar const * path, GLboolean alpha = false);
+void processInput(GLFWwindow *window);
-GLuint generateAttachmentTexture(GLboolean depth, GLboolean stencil);
+unsigned int loadTexture(const char *path);
 
-// Camera
+// settings
+const unsigned int SCR_WIDTH = 1280;
+const unsigned int SCR_HEIGHT = 720;
+
+// camera
 Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
-bool keys[1024];
+float lastX = (float)SCR_WIDTH / 2.0;
-GLfloat lastX = 400, lastY = 300;
+float lastY = (float)SCR_HEIGHT / 2.0;
 bool firstMouse = true;
 
-GLfloat deltaTime = 0.0f;
+// timing
-GLfloat lastFrame = 0.0f;
+float deltaTime = 0.0f;
+float lastFrame = 0.0f;
 
-// The MAIN function, from here we start our application and run our Game loop
 int main()
 {
-    // Init GLFW
+    // glfw: initialize and configure
+    // ------------------------------
     glfwInit();
     glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
     glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
 
-    GLFWwindow* window = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr); // Windowed
+    // glfw window creation
+    // --------------------
+    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
     glfwMakeContextCurrent(window);
-
+    if (window == NULL)
-    // Set the required callback functions
+    {
-    glfwSetKeyCallback(window, key_callback);
+        std::cout << "Failed to create GLFW window" << std::endl;
+        glfwTerminate();
+        return -1;
+    }
+    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
     glfwSetCursorPosCallback(window, mouse_callback);
     glfwSetScrollCallback(window, scroll_callback);
 
-    // Options
+    // tell GLFW to capture our mouse
     glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
 
-    // Initialize GLEW to setup the OpenGL Function pointers
+    // glad: load all OpenGL function pointers
-    glewExperimental = GL_TRUE;
+    // ---------------------------------------
-    glewInit();
+    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
+    {
+        std::cout << "Failed to initialize GLAD" << std::endl;
+        return -1;
+    }
 
-    // Define the viewport dimensions
+    // configure global opengl state
-    glViewport(0, 0, screenWidth, screenHeight);
+    // -----------------------------
+    glEnable(GL_DEPTH_TEST);
 
-    // Setup some OpenGL options
+    // build and compile shaders
-    glDepthFunc(GL_LESS);
+    // -------------------------
+    Shader shader("5.1.framebuffers.vs", "5.1.framebuffers.fs");
+    Shader screenShader("5.1.framebuffers_screen.vs", "5.1.framebuffers_screen.fs");
 
-    // Setup and compile our shaders
+    // set up vertex data (and buffer(s)) and configure vertex attributes
-    Shader shader("framebuffers.vs", "framebuffers.frag");
+    // ------------------------------------------------------------------
-    Shader screenShader("framebuffers_screen.vs", "framebuffers_screen.frag");
+    float cubeVertices[] = {
-
+        // positions          // texture Coords
-    #pragma region "object_initialization"
-    // Set the object data (buffers, vertex attributes)
-    GLfloat cubeVertices[] = {
-        // Positions          // Texture Coords
         -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
          0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
          0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
@@ -124,18 +122,18 @@ int main()
         -0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
         -0.5f,  0.5f, -0.5f,  0.0f, 1.0f
     };
-    GLfloat floorVertices[] = {
+    float planeVertices[] = {
-        // Positions          // Texture Coords (note we set these higher than 1 that together with GL_REPEAT as texture wrapping mode will cause the floor texture to repeat)
+        // positions          // texture Coords 
-        5.0f,  -0.5f,  5.0f,  2.0f, 0.0f,
+         5.0f, -0.5f,  5.0f,  2.0f, 0.0f,
         -5.0f, -0.5f,  5.0f,  0.0f, 0.0f,
         -5.0f, -0.5f, -5.0f,  0.0f, 2.0f,
 
-        5.0f,  -0.5f,  5.0f,  2.0f, 0.0f,
+         5.0f, -0.5f,  5.0f,  2.0f, 0.0f,
         -5.0f, -0.5f, -5.0f,  0.0f, 2.0f,
-        5.0f,  -0.5f, -5.0f,  2.0f, 2.0f								
+         5.0f, -0.5f, -5.0f,  2.0f, 2.0f
     };
-    GLfloat quadVertices[] = {   // Vertex attributes for a quad that fills the entire screen in Normalized Device Coordinates.
+    float quadVertices[] = { // vertex attributes for a quad that fills the entire screen in Normalized Device Coordinates.
-        // Positions   // TexCoords
+        // positions   // texCoords
         -1.0f,  1.0f,  0.0f, 1.0f,
         -1.0f, -1.0f,  0.0f, 0.0f,
          1.0f, -1.0f,  1.0f, 0.0f,
@@ -144,242 +142,202 @@ int main()
          1.0f, -1.0f,  1.0f, 0.0f,
          1.0f,  1.0f,  1.0f, 1.0f
     };
-
+    // cube VAO
-    // Setup cube VAO
+    unsigned int cubeVAO, cubeVBO;
-    GLuint cubeVAO, cubeVBO;
     glGenVertexArrays(1, &cubeVAO);
     glGenBuffers(1, &cubeVBO);
     glBindVertexArray(cubeVAO);
     glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), &cubeVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
-    glBindVertexArray(0);
+    // plane VAO
-    // Setup plane VAO
+    unsigned int planeVAO, planeVBO;
-    GLuint floorVAO, floorVBO;
+    glGenVertexArrays(1, &planeVAO);
-    glGenVertexArrays(1, &floorVAO);
+    glGenBuffers(1, &planeVBO);
-    glGenBuffers(1, &floorVBO);
+    glBindVertexArray(planeVAO);
-    glBindVertexArray(floorVAO);
+    glBindBuffer(GL_ARRAY_BUFFER, planeVBO);
-    glBindBuffer(GL_ARRAY_BUFFER, floorVBO);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(planeVertices), &planeVertices, GL_STATIC_DRAW);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(floorVertices), &floorVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
-    glBindVertexArray(0);
+    // screen quad VAO
-    // Setup screen VAO
+    unsigned int quadVAO, quadVBO;
-    GLuint quadVAO, quadVBO;
     glGenVertexArrays(1, &quadVAO);
     glGenBuffers(1, &quadVBO);
     glBindVertexArray(quadVAO);
     glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(quadVertices), &quadVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)(2 * sizeof(GLfloat)));
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)(2 * sizeof(float)));
-    glBindVertexArray(0);
 
-    // Load textures
+    // load textures
-    GLuint cubeTexture = loadTexture(FileSystem::getPath("resources/textures/container.jpg").c_str());
+    // -------------
-    GLuint floorTexture = loadTexture(FileSystem::getPath("resources/textures/metal.png").c_str());
+    unsigned int cubeTexture = loadTexture(FileSystem::getPath("resources/textures/marble.jpg").c_str());
-    #pragma endregion
+    unsigned int floorTexture = loadTexture(FileSystem::getPath("resources/textures/metal.png").c_str());
 
-    // Framebuffers
+    // shader configuration
-    GLuint framebuffer;
+    // --------------------
+    shader.use();
+    shader.setInt("texture1", 0);
+
+    screenShader.use();
+    screenShader.setInt("screenTexture", 0);
+
+    // framebuffer configuration
+    // -------------------------
+    unsigned int framebuffer;
     glGenFramebuffers(1, &framebuffer);
     glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
-    // Create a color attachment texture
+    // create a color attachment texture
-    GLuint textureColorbuffer = generateAttachmentTexture(false, false);
+    unsigned int textureColorbuffer;
+    glGenTextures(1, &textureColorbuffer);
+    glBindTexture(GL_TEXTURE_2D, textureColorbuffer);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureColorbuffer, 0);
-    // Create a renderbuffer object for depth and stencil attachment (we won't be sampling these)
+    // create a renderbuffer object for depth and stencil attachment (we won't be sampling these)
-    GLuint rbo;
+    unsigned int rbo;
     glGenRenderbuffers(1, &rbo);
     glBindRenderbuffer(GL_RENDERBUFFER, rbo);
-    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, screenWidth, screenHeight); // Use a single renderbuffer object for both a depth AND stencil buffer.
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, SCR_WIDTH, SCR_HEIGHT); // use a single renderbuffer object for both a depth AND stencil buffer.
-    glBindRenderbuffer(GL_RENDERBUFFER, 0);
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo); // now actually attach it
-    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo); // Now actually attach it
+    // now that we actually created the framebuffer and added all attachments we want to check if it is actually complete now
-    // Now that we actually created the framebuffer and added all attachments we want to check if it is actually complete now
+    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
-    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
         cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << endl;
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
 
-
+    // draw as wireframe
-    // Draw as wireframe
     //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 
-    // Game loop
+    // render loop
-    while(!glfwWindowShouldClose(window))
+    // -----------
+    while (!glfwWindowShouldClose(window))
     {
-        // Set frame time
+        // per-frame time logic
-        GLfloat currentFrame = glfwGetTime();
+        // --------------------
+        float currentFrame = glfwGetTime();
         deltaTime = currentFrame - lastFrame;
         lastFrame = currentFrame;
 
-        // Check and call events
+        // input
-        glfwPollEvents();
+        // -----
-        Do_Movement();
+        processInput(window);
 
 
-        /////////////////////////////////////////////////////
+        // render
-        // Bind to framebuffer and draw to color texture 
+        // ------
-        // as we normally would.
+        // bind to framebuffer and draw scene as we normally would to color texture 
-        // //////////////////////////////////////////////////
         glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
-        // Clear all attached buffers        
+        glEnable(GL_DEPTH_TEST); // enable depth testing (is disabled for rendering screen-space quad)
-        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
-        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // We're not using stencil buffer so why bother with clearing?
 
-        glEnable(GL_DEPTH_TEST);
+        // make sure we clear the framebuffer's content
-        // Set uniforms
+        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
-        shader.Use();
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+        shader.use();
         glm::mat4 model;
         glm::mat4 view = camera.GetViewMatrix();
-        glm::mat4 projection = glm::perspective(camera.Zoom, (float)screenWidth/(float)screenHeight, 0.1f, 100.0f);
+        glm::mat4 projection = glm::perspective(camera.Zoom, (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
+        shader.setMat4("view", view);
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
+        shader.setMat4("projection", projection);
-
+        // cubes
-        // Floor
-        glBindVertexArray(floorVAO);
-        glBindTexture(GL_TEXTURE_2D, floorTexture);
-        model = glm::mat4();
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
-        glDrawArrays(GL_TRIANGLES, 0, 6);		
-        glBindVertexArray(0);	
-        // Cubes
         glBindVertexArray(cubeVAO);
+        glActiveTexture(GL_TEXTURE0);
         glBindTexture(GL_TEXTURE_2D, cubeTexture);
         model = glm::translate(model, glm::vec3(-1.0f, 0.0f, -1.0f));
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shader.setMat4("model", model);
         glDrawArrays(GL_TRIANGLES, 0, 36);
         model = glm::mat4();
         model = glm::translate(model, glm::vec3(2.0f, 0.0f, 0.0f));
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shader.setMat4("model", model);
         glDrawArrays(GL_TRIANGLES, 0, 36);
-        glBindVertexArray(0);			
+        // floor
-
+        glBindVertexArray(planeVAO);
-        /////////////////////////////////////////////////////
+        glBindTexture(GL_TEXTURE_2D, floorTexture);
-        // Bind to default framebuffer again and draw the 
+        shader.setMat4("model", glm::mat4());
-        // quad plane with attched screen texture.
-        // //////////////////////////////////////////////////
-        glBindFramebuffer(GL_FRAMEBUFFER, 0);
-        // Clear all relevant buffers
-        glClearColor(1.0f, 1.0f, 1.0f, 1.0f); // Set clear color to white (not really necessery actually, since we won't be able to see behind the quad anyways)
-        glClear(GL_COLOR_BUFFER_BIT);
-        glDisable(GL_DEPTH_TEST); // We don't care about depth information when rendering a single quad
-
-        // Draw Screen
-        screenShader.Use();
-        glBindVertexArray(quadVAO);
-        glBindTexture(GL_TEXTURE_2D, textureColorbuffer);	// Use the color attachment texture as the texture of the quad plane
         glDrawArrays(GL_TRIANGLES, 0, 6);
         glBindVertexArray(0);
 
+        // now bind back to default framebuffer and draw a quad plane with the attached framebuffer color texture
+        glBindFramebuffer(GL_FRAMEBUFFER, 0);
+        glDisable(GL_DEPTH_TEST); // disable depth test so screen-space quad isn't discarded due to depth test.
+        // clear all relevant buffers
+        glClearColor(1.0f, 1.0f, 1.0f, 1.0f); // set clear color to white (not really necessery actually, since we won't be able to see behind the quad anyways)
+        glClear(GL_COLOR_BUFFER_BIT);
 
-        // Swap the buffers
+        screenShader.use();
+        glBindVertexArray(quadVAO);
+        glBindTexture(GL_TEXTURE_2D, textureColorbuffer);	// use the color attachment texture as the texture of the quad plane
+        glDrawArrays(GL_TRIANGLES, 0, 6);
+
+
+        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
+        // -------------------------------------------------------------------------------
         glfwSwapBuffers(window);
+        glfwPollEvents();
     }
 
-    // Clean up
+    // optional: de-allocate all resources once they've outlived their purpose:
-    glDeleteFramebuffers(1, &framebuffer);
+    // ------------------------------------------------------------------------
+    glDeleteVertexArrays(1, &cubeVAO);
+    glDeleteVertexArrays(1, &planeVAO);
+    glDeleteVertexArrays(1, &quadVAO);
+    glDeleteBuffers(1, &cubeVBO);
+    glDeleteBuffers(1, &planeVBO);
+    glDeleteBuffers(1, &quadVBO);
 
     glfwTerminate();
     return 0;
 }
 
-// This function loads a texture from file. Note: texture loading functions like these are usually 
+// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
-// managed by a 'Resource Manager' that manages all resources (like textures, models, audio). 
+// ---------------------------------------------------------------------------------------------------------
-// For learning purposes we'll just define it as a utility function.
+void processInput(GLFWwindow *window)
-GLuint loadTexture(GLchar const * path, GLboolean alpha)
 {
-    //Generate texture ID and load texture data 
+    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
-    GLuint textureID;
+        glfwSetWindowShouldClose(window, true);
-    glGenTextures(1, &textureID);
-    int width,height;
-    unsigned char* image = SOIL_load_image(path, &width, &height, 0, alpha ? SOIL_LOAD_RGBA : SOIL_LOAD_RGB);
-    // Assign texture to ID
-    glBindTexture(GL_TEXTURE_2D, textureID);
-    glTexImage2D(GL_TEXTURE_2D, 0, alpha ? GL_RGBA : GL_RGB, width, height, 0, alpha ? GL_RGBA : GL_RGB, GL_UNSIGNED_BYTE, image);
-    glGenerateMipmap(GL_TEXTURE_2D);	
 
-    // Parameters
+    float cameraSpeed = 2.5 * deltaTime;
-    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, alpha ? GL_CLAMP_TO_EDGE : GL_REPEAT );	// Use GL_MIRRORED_REPEAT to prevent white borders. Due to interpolation it takes value from next repeat 
+    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
-    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, alpha ? GL_CLAMP_TO_EDGE : GL_REPEAT );
-    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR );
-    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glBindTexture(GL_TEXTURE_2D, 0);
-    SOIL_free_image_data(image);
-    return textureID;
-}
-
-// Generates a texture that is suited for attachments to a framebuffer
-GLuint generateAttachmentTexture(GLboolean depth, GLboolean stencil)
-{
-    // What enum to use?
-    GLenum attachment_type;
-    if(!depth && !stencil)
-        attachment_type = GL_RGB;
-    else if(depth && !stencil)
-        attachment_type = GL_DEPTH_COMPONENT;
-    else if(!depth && stencil)
-        attachment_type = GL_STENCIL_INDEX;
-
-    //Generate texture ID and load texture data 
-    GLuint textureID;
-    glGenTextures(1, &textureID);
-    glBindTexture(GL_TEXTURE_2D, textureID);
-    if(!depth && !stencil)
-        glTexImage2D(GL_TEXTURE_2D, 0, attachment_type, screenWidth, screenHeight, 0, attachment_type, GL_UNSIGNED_BYTE, NULL);
-    else // Using both a stencil and depth test, needs special format arguments
-        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH24_STENCIL8, screenWidth, screenHeight, 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, NULL);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glBindTexture(GL_TEXTURE_2D, 0);
-
-    return textureID;
-}
-
-#pragma region "User input"
-
-// Moves/alters the camera positions based on user input
-void Do_Movement()
-{
-    // Camera controls
-    if(keys[GLFW_KEY_W])
         camera.ProcessKeyboard(FORWARD, deltaTime);
-    if(keys[GLFW_KEY_S])
+    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
         camera.ProcessKeyboard(BACKWARD, deltaTime);
-    if(keys[GLFW_KEY_A])
+    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
         camera.ProcessKeyboard(LEFT, deltaTime);
-    if(keys[GLFW_KEY_D])
+    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
         camera.ProcessKeyboard(RIGHT, deltaTime);
 }
 
-// Is called whenever a key is pressed/released via GLFW
+// glfw: whenever the window size changed (by OS or user resize) this callback function executes
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
+// ---------------------------------------------------------------------------------------------
+void framebuffer_size_callback(GLFWwindow* window, int width, int height)
 {
-    if(key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+    // make sure the viewport matches the new window dimensions; note that width and 
-        glfwSetWindowShouldClose(window, GL_TRUE);
+    // height will be significantly larger than specified on retina displays.
-
+    glViewport(0, 0, width, height);
-    if(action == GLFW_PRESS)
-        keys[key] = true;
-    else if(action == GLFW_RELEASE)
-        keys[key] = false;	
 }
 
+
+// glfw: whenever the mouse moves, this callback is called
+// -------------------------------------------------------
 void mouse_callback(GLFWwindow* window, double xpos, double ypos)
 {
-    if(firstMouse)
+    if (firstMouse)
     {
         lastX = xpos;
         lastY = ypos;
         firstMouse = false;
     }
 
-    GLfloat xoffset = xpos - lastX;
+    float xoffset = xpos - lastX;
-    GLfloat yoffset = lastY - ypos; 
+    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top
 
     lastX = xpos;
     lastY = ypos;
@@ -387,9 +345,48 @@ void mouse_callback(GLFWwindow* window, double xpos, double ypos)
     camera.ProcessMouseMovement(xoffset, yoffset);
 }
 
+// glfw: whenever the mouse scroll wheel scrolls, this callback is called
+// ----------------------------------------------------------------------
 void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
 {
     camera.ProcessMouseScroll(yoffset);
 }
 
-#pragma endregion
+// utility function for loading a 2D texture from file
+// ---------------------------------------------------
+unsigned int loadTexture(char const * path)
+{
+    unsigned int textureID;
+    glGenTextures(1, &textureID);
+
+    int width, height, nrComponents;
+    unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
+    if (data)
+    {
+        GLenum format;
+        if (nrComponents == 1)
+            format = GL_RED;
+        else if (nrComponents == 3)
+            format = GL_RGB;
+        else if (nrComponents == 4)
+            format = GL_RGBA;
+
+        glBindTexture(GL_TEXTURE_2D, textureID);
+        glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
+        glGenerateMipmap(GL_TEXTURE_2D);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        stbi_image_free(data);
+    }
+    else
+    {
+        std::cout << "Texture failed to load at path: " << path << std::endl;
+        stbi_image_free(data);
+    }
+
+    return textureID;
+}

src/4.advanced_opengl/5.2.framebuffers_exercise1/framebuffers_exercise1.cpp

@@ -1,87 +1,85 @@
-// Std. Includes
+#include <glad/glad.h>
-#include <string>
-#include <algorithm>
-using namespace std;
-
-// GLEW
-#define GLEW_STATIC
-#include <GL/glew.h>
-
-// GLFW
 #include <GLFW/glfw3.h>
+#include <stb_image.h>
 
-// GL includes
-#include <learnopengl/shader.h>
-#include <learnopengl/camera.h>
-
-// GLM Mathemtics
 #include <glm/glm.hpp>
 #include <glm/gtc/matrix_transform.hpp>
 #include <glm/gtc/type_ptr.hpp>
 
-// Other Libs
-#include <SOIL.h>
 #include <learnopengl/filesystem.h>
+#include <learnopengl/shader_m.h>
+#include <learnopengl/camera.h>
+#include <learnopengl/model.h>
 
-// Properties
+#include <iostream>
-GLuint screenWidth = 800, screenHeight = 600;
 
-// Function prototypes
+void framebuffer_size_callback(GLFWwindow* window, int width, int height);
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
-void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
 void mouse_callback(GLFWwindow* window, double xpos, double ypos);
-void Do_Movement();
+void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
-GLuint loadTexture(GLchar const * path, GLboolean alpha = false);
+void processInput(GLFWwindow *window);
-GLuint generateAttachmentTexture(GLboolean depth, GLboolean stencil);
+unsigned int loadTexture(const char *path);
 
-// Camera
+// settings
+const unsigned int SCR_WIDTH = 1280;
+const unsigned int SCR_HEIGHT = 720;
+
+// camera
 Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
-bool keys[1024];
+float lastX = (float)SCR_WIDTH / 2.0;
-GLfloat lastX = 400, lastY = 300;
+float lastY = (float)SCR_HEIGHT / 2.0;
 bool firstMouse = true;
 
-GLfloat deltaTime = 0.0f;
+// timing
-GLfloat lastFrame = 0.0f;
+float deltaTime = 0.0f;
+float lastFrame = 0.0f;
 
-// The MAIN function, from here we start our application and run our Game loop
 int main()
 {
-    // Init GLFW
+    // glfw: initialize and configure
+    // ------------------------------
     glfwInit();
     glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
     glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
 
-    GLFWwindow* window = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr); // Windowed
+    // glfw window creation
+    // --------------------
+    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
     glfwMakeContextCurrent(window);
-
+    if (window == NULL)
-    // Set the required callback functions
+    {
-    glfwSetKeyCallback(window, key_callback);
+        std::cout << "Failed to create GLFW window" << std::endl;
+        glfwTerminate();
+        return -1;
+    }
+    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
     glfwSetCursorPosCallback(window, mouse_callback);
     glfwSetScrollCallback(window, scroll_callback);
 
-    // Options
+    // tell GLFW to capture our mouse
     glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
 
-    // Initialize GLEW to setup the OpenGL Function pointers
+    // glad: load all OpenGL function pointers
-    glewExperimental = GL_TRUE;
+    // ---------------------------------------
-    glewInit();
+    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
+    {
+        std::cout << "Failed to initialize GLAD" << std::endl;
+        return -1;
+    }
 
-    // Define the viewport dimensions
+    // configure global opengl state
-    glViewport(0, 0, screenWidth, screenHeight);
+    // -----------------------------
+    glEnable(GL_DEPTH_TEST);
 
-    // Setup some OpenGL options
+    // build and compile shaders
-    glDepthFunc(GL_LESS);
+    // -------------------------
+    Shader shader("5.1.framebuffers.vs", "5.1.framebuffers.fs");
+    Shader screenShader("5.1.framebuffers_screen.vs", "5.1.framebuffers_screen.fs");
 
-    // Setup and compile our shaders
+    // set up vertex data (and buffer(s)) and configure vertex attributes
-    Shader shader("framebuffers.vs", "framebuffers.frag");
+    // ------------------------------------------------------------------
-    Shader screenShader("framebuffers_screen.vs", "framebuffers_screen.frag");
+    float cubeVertices[] = {
-
+        // positions          // texture Coords
-    #pragma region "object_initialization"
-    // Set the object data (buffers, vertex attributes)
-    GLfloat cubeVertices[] = {
-        // Positions          // Texture Coords
         -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
          0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
          0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
@@ -124,262 +122,256 @@ int main()
         -0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
         -0.5f,  0.5f, -0.5f,  0.0f, 1.0f
     };
-    GLfloat floorVertices[] = {
+    float planeVertices[] = {
-        // Positions          // Texture Coords (note we set these higher than 1 that together with GL_REPEAT as texture wrapping mode will cause the floor texture to repeat)
+        // positions          // texture Coords 
-        5.0f,  -0.5f,  5.0f,  2.0f, 0.0f,
+         5.0f, -0.5f,  5.0f,  2.0f, 0.0f,
         -5.0f, -0.5f,  5.0f,  0.0f, 0.0f,
         -5.0f, -0.5f, -5.0f,  0.0f, 2.0f,
 
-        5.0f,  -0.5f,  5.0f,  2.0f, 0.0f,
+         5.0f, -0.5f,  5.0f,  2.0f, 0.0f,
         -5.0f, -0.5f, -5.0f,  0.0f, 2.0f,
-        5.0f,  -0.5f, -5.0f,  2.0f, 2.0f								
+         5.0f, -0.5f, -5.0f,  2.0f, 2.0f
     };
-    GLfloat quadVertices[] = {   // Vertex attributes for a quad that fills the entire screen in Normalized Device Coordinates.
+    float quadVertices[] = { // vertex attributes for a quad that fills the entire screen in Normalized Device Coordinates. NOTE that this plane is now much smaller and at the top of the screen
-        // Positions   // TexCoords
+        // positions   // texCoords
-        -1.0f,  1.0f,  0.0f, 1.0f,
+        -0.3f,  1.0f,  0.0f, 1.0f,
-        -1.0f, -1.0f,  0.0f, 0.0f,
+        -0.3f,  0.7f,  0.0f, 0.0f,
-         1.0f, -1.0f,  1.0f, 0.0f,
+         0.3f,  0.7f,  1.0f, 0.0f,
 
-        -1.0f,  1.0f,  0.0f, 1.0f,
+        -0.3f,  1.0f,  0.0f, 1.0f,
-         1.0f, -1.0f,  1.0f, 0.0f,
+         0.3f,  0.7f,  1.0f, 0.0f,
-         1.0f,  1.0f,  1.0f, 1.0f
+         0.3f,  1.0f,  1.0f, 1.0f
     };
-
+    // cube VAO
-    // Setup cube VAO
+    unsigned int cubeVAO, cubeVBO;
-    GLuint cubeVAO, cubeVBO;
     glGenVertexArrays(1, &cubeVAO);
     glGenBuffers(1, &cubeVBO);
     glBindVertexArray(cubeVAO);
     glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), &cubeVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
-    glBindVertexArray(0);
+    // plane VAO
-    // Setup plane VAO
+    unsigned int planeVAO, planeVBO;
-    GLuint floorVAO, floorVBO;
+    glGenVertexArrays(1, &planeVAO);
-    glGenVertexArrays(1, &floorVAO);
+    glGenBuffers(1, &planeVBO);
-    glGenBuffers(1, &floorVBO);
+    glBindVertexArray(planeVAO);
-    glBindVertexArray(floorVAO);
+    glBindBuffer(GL_ARRAY_BUFFER, planeVBO);
-    glBindBuffer(GL_ARRAY_BUFFER, floorVBO);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(planeVertices), &planeVertices, GL_STATIC_DRAW);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(floorVertices), &floorVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
-    glBindVertexArray(0);
+    // screen quad VAO
-    // Setup screen VAO
+    unsigned int quadVAO, quadVBO;
-    GLuint quadVAO, quadVBO;
     glGenVertexArrays(1, &quadVAO);
     glGenBuffers(1, &quadVBO);
     glBindVertexArray(quadVAO);
     glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(quadVertices), &quadVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)(2 * sizeof(GLfloat)));
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)(2 * sizeof(float)));
-    glBindVertexArray(0);
 
-    // Load textures
+    // load textures
-    GLuint cubeTexture = loadTexture(FileSystem::getPath("resources/textures/container.jpg").c_str());
+    // -------------
-    GLuint floorTexture = loadTexture(FileSystem::getPath("resources/textures/metal.png").c_str());
+    unsigned int cubeTexture = loadTexture(FileSystem::getPath("resources/textures/marble.jpg").c_str());
-    #pragma endregion
+    unsigned int floorTexture = loadTexture(FileSystem::getPath("resources/textures/metal.png").c_str());
 
-    // Framebuffers
+    // shader configuration
-    GLuint framebuffer;
+    // --------------------
+    shader.use();
+    shader.setInt("texture1", 0);
+
+    screenShader.use();
+    screenShader.setInt("screenTexture", 0);
+
+    // framebuffer configuration
+    // -------------------------
+    unsigned int framebuffer;
     glGenFramebuffers(1, &framebuffer);
     glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
-    // Create a color attachment texture
+    // create a color attachment texture
-    GLuint textureColorbuffer = generateAttachmentTexture(false, false);
+    unsigned int textureColorbuffer;
+    glGenTextures(1, &textureColorbuffer);
+    glBindTexture(GL_TEXTURE_2D, textureColorbuffer);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureColorbuffer, 0);
-    // Create a renderbuffer object for depth and stencil attachment (we won't be sampling these)
+    // create a renderbuffer object for depth and stencil attachment (we won't be sampling these)
-    GLuint rbo;
+    unsigned int rbo;
     glGenRenderbuffers(1, &rbo);
     glBindRenderbuffer(GL_RENDERBUFFER, rbo);
-    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, screenWidth, screenHeight); // Use a single renderbuffer object for both a depth AND stencil buffer.
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, SCR_WIDTH, SCR_HEIGHT); // use a single renderbuffer object for both a depth AND stencil buffer.
-    glBindRenderbuffer(GL_RENDERBUFFER, 0);
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo); // now actually attach it
-    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo); // Now actually attach it
+                                                                                                  // now that we actually created the framebuffer and added all attachments we want to check if it is actually complete now
-    // Now that we actually created the framebuffer and added all attachments we want to check if it is actually complete now
+    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
-    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
         cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << endl;
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
 
-
+    // draw as wireframe
-    // Draw as wireframe
     //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 
-    // Game loop
+    // render loop
-    while(!glfwWindowShouldClose(window))
+    // -----------
+    while (!glfwWindowShouldClose(window))
     {
-        // Set frame time
+        // per-frame time logic
-        GLfloat currentFrame = glfwGetTime();
+        // --------------------
+        float currentFrame = glfwGetTime();
         deltaTime = currentFrame - lastFrame;
         lastFrame = currentFrame;
 
-        // Check and call events
+        // input
-        glfwPollEvents();
+        // -----
-        Do_Movement();
+        processInput(window);
 
 
-        /////////////////////////////////////////////////////
+        // first render pass: mirror texture.
-        // Bind to framebuffer and draw to color texture 
+        // bind to framebuffer and draw to color texture as we normally 
-        // as we normally would.
+        // would, but with the view camera reversed.
-        // //////////////////////////////////////////////////
+        // bind to framebuffer and draw scene as we normally would to color texture 
+        // ------------------------------------------------------------------------
         glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
-        // Clear all attached buffers        
+        glEnable(GL_DEPTH_TEST); // enable depth testing (is disabled for rendering screen-space quad)
+
+        // make sure we clear the framebuffer's content
         glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
-        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // We're not using stencil buffer so why bother with clearing?
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-        glEnable(GL_DEPTH_TEST);
+        shader.use();
-        // Set uniforms
-        shader.Use();
         glm::mat4 model;
+        camera.Yaw   += 180.0f; // rotate the camera's yaw 180 degrees around
+        camera.Pitch += 180.0f; // rotate the camera's pitch 180 degrees around
+        camera.ProcessMouseMovement(0, 0, false); // call this to make sure it updates its camera vectors, note that we disable pitch constrains for this specific case (otherwise we can't reverse camera's pitch values)
         glm::mat4 view = camera.GetViewMatrix();
-        glm::mat4 projection = glm::perspective(camera.Zoom, (float)screenWidth/(float)screenHeight, 0.1f, 100.0f);
+        camera.Yaw   -= 180.0f; // reset it back to its original orientation
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
+        camera.Pitch -= 180.0f;
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
+        camera.ProcessMouseMovement(0, 0, true); 
-
+        glm::mat4 projection = glm::perspective(camera.Zoom, (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
-        // Floor
+        shader.setMat4("view", view);
-        glBindVertexArray(floorVAO);
+        shader.setMat4("projection", projection);
-        glBindTexture(GL_TEXTURE_2D, floorTexture);
+        // cubes
-        model = glm::mat4();
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
-        glDrawArrays(GL_TRIANGLES, 0, 6);		
-        glBindVertexArray(0);	
-        // Cubes
         glBindVertexArray(cubeVAO);
+        glActiveTexture(GL_TEXTURE0);
         glBindTexture(GL_TEXTURE_2D, cubeTexture);
         model = glm::translate(model, glm::vec3(-1.0f, 0.0f, -1.0f));
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shader.setMat4("model", model);
         glDrawArrays(GL_TRIANGLES, 0, 36);
         model = glm::mat4();
         model = glm::translate(model, glm::vec3(2.0f, 0.0f, 0.0f));
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shader.setMat4("model", model);
         glDrawArrays(GL_TRIANGLES, 0, 36);
-        glBindVertexArray(0);			
+        // floor
-
+        glBindVertexArray(planeVAO);
-        /////////////////////////////////////////////////////
+        glBindTexture(GL_TEXTURE_2D, floorTexture);
-        // Bind to default framebuffer again and draw the 
+        shader.setMat4("model", glm::mat4());
-        // quad plane with attched screen texture.
-        // //////////////////////////////////////////////////
-        glBindFramebuffer(GL_FRAMEBUFFER, 0);
-        // Clear all relevant buffers
-        glClearColor(1.0f, 1.0f, 1.0f, 1.0f); // Set clear color to white (not really necessery actually, since we won't be able to see behind the quad anyways)
-        glClear(GL_COLOR_BUFFER_BIT);
-        glDisable(GL_DEPTH_TEST); // We don't care about depth information when rendering a single quad
-
-        // Draw Screen
-        screenShader.Use();
-        glBindVertexArray(quadVAO);
-        glBindTexture(GL_TEXTURE_2D, textureColorbuffer);	// Use the color attachment texture as the texture of the quad plane
         glDrawArrays(GL_TRIANGLES, 0, 6);
         glBindVertexArray(0);
 
+        // second render pass: draw as normal
+        // ----------------------------------
+        glBindFramebuffer(GL_FRAMEBUFFER, 0);
 
-        // Swap the buffers
+        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+        model = glm::mat4();
+        view = camera.GetViewMatrix();
+        shader.setMat4("view", view);
+
+        // cubes
+        glBindVertexArray(cubeVAO);
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_2D, cubeTexture);
+        model = glm::translate(model, glm::vec3(-1.0f, 0.0f, -1.0f));
+        shader.setMat4("model", model);
+        glDrawArrays(GL_TRIANGLES, 0, 36);
+        model = glm::mat4();
+        model = glm::translate(model, glm::vec3(2.0f, 0.0f, 0.0f));
+        shader.setMat4("model", model);
+        glDrawArrays(GL_TRIANGLES, 0, 36);
+        // floor
+        glBindVertexArray(planeVAO);
+        glBindTexture(GL_TEXTURE_2D, floorTexture);
+        shader.setMat4("model", glm::mat4());
+        glDrawArrays(GL_TRIANGLES, 0, 6);
+        glBindVertexArray(0);
+
+        // now draw the mirror quad with screen texture
+        // --------------------------------------------
+        glDisable(GL_DEPTH_TEST); // disable depth test so screen-space quad isn't discarded due to depth test.
+
+        screenShader.use();
+        glBindVertexArray(quadVAO);
+        glBindTexture(GL_TEXTURE_2D, textureColorbuffer);	// use the color attachment texture as the texture of the quad plane
+        glDrawArrays(GL_TRIANGLES, 0, 6);
+
+
+        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
+        // -------------------------------------------------------------------------------
         glfwSwapBuffers(window);
+        glfwPollEvents();
     }
 
-    // Clean up
+    // optional: de-allocate all resources once they've outlived their purpose:
-    glDeleteFramebuffers(1, &framebuffer);
+    // ------------------------------------------------------------------------
+    glDeleteVertexArrays(1, &cubeVAO);
+    glDeleteVertexArrays(1, &planeVAO);
+    glDeleteVertexArrays(1, &quadVAO);
+    glDeleteBuffers(1, &cubeVBO);
+    glDeleteBuffers(1, &planeVBO);
+    glDeleteBuffers(1, &quadVBO);
 
     glfwTerminate();
     return 0;
 }
 
-// This function loads a texture from file. Note: texture loading functions like these are usually 
+// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
-// managed by a 'Resource Manager' that manages all resources (like textures, models, audio). 
+// ---------------------------------------------------------------------------------------------------------
-// For learning purposes we'll just define it as a utility function.
+void processInput(GLFWwindow *window)
-GLuint loadTexture(GLchar const * path, GLboolean alpha)
 {
-    //Generate texture ID and load texture data 
+    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
-    GLuint textureID;
+        glfwSetWindowShouldClose(window, true);
-    glGenTextures(1, &textureID);
-    int width,height;
-    unsigned char* image = SOIL_load_image(path, &width, &height, 0, alpha ? SOIL_LOAD_RGBA : SOIL_LOAD_RGB);
-    // Assign texture to ID
-    glBindTexture(GL_TEXTURE_2D, textureID);
-    glTexImage2D(GL_TEXTURE_2D, 0, alpha ? GL_RGBA : GL_RGB, width, height, 0, alpha ? GL_RGBA : GL_RGB, GL_UNSIGNED_BYTE, image);
-    glGenerateMipmap(GL_TEXTURE_2D);	
 
-    // Parameters
+    float cameraSpeed = 2.5 * deltaTime;
-    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, alpha ? GL_CLAMP_TO_EDGE : GL_REPEAT );	// Use GL_MIRRORED_REPEAT to prevent white borders. Due to interpolation it takes value from next repeat 
+    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
-    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, alpha ? GL_CLAMP_TO_EDGE : GL_REPEAT );
-    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR );
-    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glBindTexture(GL_TEXTURE_2D, 0);
-    SOIL_free_image_data(image);
-    return textureID;
-}
-
-// Generates a texture that is suited for attachments to a framebuffer
-GLuint generateAttachmentTexture(GLboolean depth, GLboolean stencil)
-{
-    // What enum to use?
-    GLenum attachment_type;
-    if(!depth && !stencil)
-        attachment_type = GL_RGB;
-    else if(depth && !stencil)
-        attachment_type = GL_DEPTH_COMPONENT;
-    else if(!depth && stencil)
-        attachment_type = GL_STENCIL_INDEX;
-
-    //Generate texture ID and load texture data 
-    GLuint textureID;
-    glGenTextures(1, &textureID);
-    glBindTexture(GL_TEXTURE_2D, textureID);
-    if(!depth && !stencil)
-        glTexImage2D(GL_TEXTURE_2D, 0, attachment_type, screenWidth, screenHeight, 0, attachment_type, GL_UNSIGNED_BYTE, NULL);
-    else // Using both a stencil and depth test, needs special format arguments
-        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH24_STENCIL8, screenWidth, screenHeight, 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, NULL);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glBindTexture(GL_TEXTURE_2D, 0);
-
-    return textureID;
-}
-
-#pragma region "User input"
-
-// Moves/alters the camera positions based on user input
-void Do_Movement()
-{
-    // Camera controls
-    if(keys[GLFW_KEY_W])
         camera.ProcessKeyboard(FORWARD, deltaTime);
-    if(keys[GLFW_KEY_S])
+    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
         camera.ProcessKeyboard(BACKWARD, deltaTime);
-    if(keys[GLFW_KEY_A])
+    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
         camera.ProcessKeyboard(LEFT, deltaTime);
-    if(keys[GLFW_KEY_D])
+    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
         camera.ProcessKeyboard(RIGHT, deltaTime);
 }
 
-// Is called whenever a key is pressed/released via GLFW
+// glfw: whenever the window size changed (by OS or user resize) this callback function executes
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
+// ---------------------------------------------------------------------------------------------
+void framebuffer_size_callback(GLFWwindow* window, int width, int height)
 {
-    if(key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+    // make sure the viewport matches the new window dimensions; note that width and 
-        glfwSetWindowShouldClose(window, GL_TRUE);
+    // height will be significantly larger than specified on retina displays.
-
+    glViewport(0, 0, width, height);
-    if(action == GLFW_PRESS)
-        keys[key] = true;
-    else if(action == GLFW_RELEASE)
-        keys[key] = false;	
 }
 
+
+// glfw: whenever the mouse moves, this callback is called
+// -------------------------------------------------------
 void mouse_callback(GLFWwindow* window, double xpos, double ypos)
 {
-    if(firstMouse)
+    if (firstMouse)
     {
         lastX = xpos;
         lastY = ypos;
         firstMouse = false;
     }
 
-    GLfloat xoffset = xpos - lastX;
+    float xoffset = xpos - lastX;
-    GLfloat yoffset = lastY - ypos; 
+    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top
 
     lastX = xpos;
     lastY = ypos;
@@ -387,9 +379,48 @@ void mouse_callback(GLFWwindow* window, double xpos, double ypos)
     camera.ProcessMouseMovement(xoffset, yoffset);
 }
 
+// glfw: whenever the mouse scroll wheel scrolls, this callback is called
+// ----------------------------------------------------------------------
 void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
 {
     camera.ProcessMouseScroll(yoffset);
 }
 
-#pragma endregion
+// utility function for loading a 2D texture from file
+// ---------------------------------------------------
+unsigned int loadTexture(char const * path)
+{
+    unsigned int textureID;
+    glGenTextures(1, &textureID);
+
+    int width, height, nrComponents;
+    unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
+    if (data)
+    {
+        GLenum format;
+        if (nrComponents == 1)
+            format = GL_RED;
+        else if (nrComponents == 3)
+            format = GL_RGB;
+        else if (nrComponents == 4)
+            format = GL_RGBA;
+
+        glBindTexture(GL_TEXTURE_2D, textureID);
+        glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
+        glGenerateMipmap(GL_TEXTURE_2D);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        stbi_image_free(data);
+    }
+    else
+    {
+        std::cout << "Texture failed to load at path: " << path << std::endl;
+        stbi_image_free(data);
+    }
+
+    return textureID;
+}

src/4.advanced_opengl/6.1.cubemaps_skybox/6.1.cubemaps.fs

@@ -1,14 +1,11 @@
 #version 330 core
-in vec3 Normal;
+out vec4 FragColor;
-in vec3 Position;
-out vec4 color;
 
-uniform vec3 cameraPos;
+in vec2 TexCoords;
-uniform samplerCube skybox;
+
+uniform sampler2D texture1;
 
 void main()
 {    
-    vec3 I = normalize(Position - cameraPos);
+    FragColor = texture(texture1, TexCoords);
-    vec3 R = reflect(I, normalize(Normal));
-    color = texture(skybox, R);
 }

src/4.advanced_opengl/6.1.cubemaps_skybox/6.1.cubemaps.vs

@@ -1,9 +1,8 @@
 #version 330 core
-layout (location = 0) in vec3 position;
+layout (location = 0) in vec3 aPos;
-layout (location = 1) in vec3 normal;
+layout (location = 1) in vec2 aTexCoords;
 
-out vec3 Normal;
+out vec2 TexCoords;
-out vec3 Position;
 
 uniform mat4 model;
 uniform mat4 view;
@@ -11,7 +10,6 @@ uniform mat4 projection;
 
 void main()
 {
-    gl_Position = projection * view * model * vec4(position, 1.0f);
+    TexCoords = aTexCoords;    
-    Normal = mat3(transpose(inverse(model))) * normal;
+    gl_Position = projection * view * model * vec4(aPos, 1.0f);
-    Position = vec3(model * vec4(position, 1.0f));
 }

src/4.advanced_opengl/6.1.cubemaps_skybox/6.1.skybox.fs

@@ -1,10 +1,11 @@
 #version 330 core
+out vec4 FragColor;
+
 in vec3 TexCoords;
-out vec4 color;
 
 uniform samplerCube skybox;
 
 void main()
 {    
-    color = texture(skybox, TexCoords);
+    FragColor = texture(skybox, TexCoords);
 }

src/4.advanced_opengl/6.1.cubemaps_skybox/6.1.skybox.vs

@@ -1,14 +1,14 @@
 #version 330 core
-layout (location = 0) in vec3 position;
+layout (location = 0) in vec3 aPos;
+
 out vec3 TexCoords;
 
 uniform mat4 projection;
 uniform mat4 view;
 
-
 void main()
 {
-    vec4 pos = projection * view * vec4(position, 1.0);
+    TexCoords = aPos;
+    vec4 pos = projection * view * vec4(aPos, 1.0);
     gl_Position = pos.xyww;
-    TexCoords = position;
 }  

src/4.advanced_opengl/6.1.cubemaps_skybox/cubemaps_skybox.cpp

@@ -1,356 +1,312 @@
-// Std. Includes
+#include <glad/glad.h>
-#include <string>
-#include <algorithm>
-using namespace std;
-
-// GLEW
-#define GLEW_STATIC
-#include <GL/glew.h>
-
-// GLFW
 #include <GLFW/glfw3.h>
+#include <stb_image.h>
 
-// GL includes
-#include <learnopengl/shader.h>
-#include <learnopengl/camera.h>
-
-// GLM Mathemtics
 #include <glm/glm.hpp>
 #include <glm/gtc/matrix_transform.hpp>
 #include <glm/gtc/type_ptr.hpp>
 
-// Other Libs
-#include <SOIL.h>
 #include <learnopengl/filesystem.h>
+#include <learnopengl/shader_m.h>
+#include <learnopengl/camera.h>
+#include <learnopengl/model.h>
 
-// Properties
+#include <iostream>
-GLuint screenWidth = 800, screenHeight = 600;
 
-// Function prototypes
+void framebuffer_size_callback(GLFWwindow* window, int width, int height);
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
-void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
 void mouse_callback(GLFWwindow* window, double xpos, double ypos);
-void Do_Movement();
+void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
-GLuint loadTexture(GLchar const * path);
+void processInput(GLFWwindow *window);
-GLuint loadCubemap(std::vector<std::string> faces);
+unsigned int loadTexture(const char *path);
+unsigned int loadCubemap(vector<std::string> faces);
 
-// Camera
+// settings
+const unsigned int SCR_WIDTH = 1280;
+const unsigned int SCR_HEIGHT = 720;
+
+// camera
 Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
-bool keys[1024];
+float lastX = (float)SCR_WIDTH / 2.0;
-GLfloat lastX = 400, lastY = 300;
+float lastY = (float)SCR_HEIGHT / 2.0;
 bool firstMouse = true;
 
-GLfloat deltaTime = 0.0f;
+// timing
-GLfloat lastFrame = 0.0f;
+float deltaTime = 0.0f;
+float lastFrame = 0.0f;
 
-
-
-// The MAIN function, from here we start our application and run our Game loop
 int main()
 {
-    // Init GLFW
+    // glfw: initialize and configure
+    // ------------------------------
     glfwInit();
     glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
     glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
 
-    GLFWwindow* window = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr); // Windowed
+    // glfw window creation
+    // --------------------
+    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
     glfwMakeContextCurrent(window);
-
+    if (window == NULL)
-    // Set the required callback functions
+    {
-    glfwSetKeyCallback(window, key_callback);
+        std::cout << "Failed to create GLFW window" << std::endl;
+        glfwTerminate();
+        return -1;
+    }
+    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
     glfwSetCursorPosCallback(window, mouse_callback);
     glfwSetScrollCallback(window, scroll_callback);
 
-    // Options
+    // tell GLFW to capture our mouse
     glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
 
-    // Initialize GLEW to setup the OpenGL Function pointers
+    // glad: load all OpenGL function pointers
-    glewExperimental = GL_TRUE;
+    // ---------------------------------------
-    glewInit();
+    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
+    {
+        std::cout << "Failed to initialize GLAD" << std::endl;
+        return -1;
+    }
 
-    // Define the viewport dimensions
+    // configure global opengl state
-    glViewport(0, 0, screenWidth, screenHeight);
+    // -----------------------------
-
-    // Setup some OpenGL options
     glEnable(GL_DEPTH_TEST);
-    glDepthFunc(GL_LESS);
 
-    // Setup and compile our shaders
+    // build and compile shaders
-    Shader shader("cubemaps.vs", "cubemaps.frag");
+    // -------------------------
-    Shader skyboxShader("skybox.vs", "skybox.frag");
+    Shader shader("6.1.cubemaps.vs", "6.1.cubemaps.fs");
+    Shader skyboxShader("6.1.skybox.vs", "6.1.skybox.fs");
 
-#pragma region "object_initialization"
+    // set up vertex data (and buffer(s)) and configure vertex attributes
-    // Set the object data (buffers, vertex attributes)
+    // ------------------------------------------------------------------
-    GLfloat cubeVertices[] = {
+    float cubeVertices[] = {
-        // Positions          // Normals
+        // positions          // texture Coords
-        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
-        0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+         0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
-        0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
-        0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
-        -0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
-        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
 
-        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
-        0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
-        0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+         0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
-        0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+         0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
-        -0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+        -0.5f,  0.5f,  0.5f,  0.0f, 1.0f,
-        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
 
-        -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
-        -0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
-        -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
-        -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
-        -0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
-        -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
 
-        0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
-        0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
-        0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
-        0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
-        0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
-        0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
 
-        -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
-        0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
+         0.5f, -0.5f, -0.5f,  1.0f, 1.0f,
-        0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
+         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
-        0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
+         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
-        -0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
+        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
-        -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
 
-        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
+        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
-        0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
+         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
-        0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
+         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
-        0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
+         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
-        -0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
+        -0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
-        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f
+        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f
     };
-    GLfloat skyboxVertices[] = {
+    float skyboxVertices[] = {
-        // Positions          
+        // positions          
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
         -1.0f, -1.0f, -1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        1.0f, 1.0f, -1.0f,
+         1.0f,  1.0f, -1.0f,
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
 
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
         -1.0f, -1.0f, -1.0f,
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
-        -1.0f, 1.0f, 1.0f,
+        -1.0f,  1.0f,  1.0f,
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
 
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        1.0f, -1.0f, 1.0f,
+         1.0f, -1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, -1.0f,
+         1.0f,  1.0f, -1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
 
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
-        -1.0f, 1.0f, 1.0f,
+        -1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, -1.0f, 1.0f,
+         1.0f, -1.0f,  1.0f,
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
 
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
-        1.0f, 1.0f, -1.0f,
+         1.0f,  1.0f, -1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        -1.0f, 1.0f, 1.0f,
+        -1.0f,  1.0f,  1.0f,
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
 
         -1.0f, -1.0f, -1.0f,
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
-        1.0f, -1.0f, 1.0f
+         1.0f, -1.0f,  1.0f
     };
 
-    // Setup cube VAO
+    // cube VAO
-    GLuint cubeVAO, cubeVBO;
+    unsigned int cubeVAO, cubeVBO;
     glGenVertexArrays(1, &cubeVAO);
     glGenBuffers(1, &cubeVBO);
     glBindVertexArray(cubeVAO);
     glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), &cubeVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
-    glBindVertexArray(0);
+    // skybox VAO
-    // Setup skybox VAO
+    unsigned int skyboxVAO, skyboxVBO;
-    GLuint skyboxVAO, skyboxVBO;
     glGenVertexArrays(1, &skyboxVAO);
     glGenBuffers(1, &skyboxVBO);
     glBindVertexArray(skyboxVAO);
     glBindBuffer(GL_ARRAY_BUFFER, skyboxVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(skyboxVertices), &skyboxVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
-    glBindVertexArray(0);
 
-#pragma endregion
+    // load textures
+    // -------------
+    unsigned int cubeTexture = loadTexture(FileSystem::getPath("resources/textures/marble.jpg").c_str());
 
-    // Cubemap (Skybox)
+    vector<std::string> faces
-    std::vector<std::string> faces;
+    {
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/right.jpg"));
+        FileSystem::getPath("resources/textures/skybox/right.jpg"),
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/left.jpg"));
+        FileSystem::getPath("resources/textures/skybox/left.jpg"),
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/top.jpg"));
+        FileSystem::getPath("resources/textures/skybox/top.jpg"),
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/bottom.jpg"));
+        FileSystem::getPath("resources/textures/skybox/bottom.jpg"),
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/back.jpg"));
+        FileSystem::getPath("resources/textures/skybox/back.jpg"),
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/front.jpg"));
+        FileSystem::getPath("resources/textures/skybox/front.jpg")
-    GLuint skyboxTexture = loadCubemap(faces);
+    };
+    unsigned int cubemapTexture = loadCubemap(faces);
 
-    // Draw as wireframe
+    // shader configuration
-    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+    // --------------------
+    shader.use();
+    shader.setInt("texture1", 0);
 
-    // Game loop
+    skyboxShader.use();
+    skyboxShader.setInt("skybox", 0);
+
+    // render loop
+    // -----------
     while (!glfwWindowShouldClose(window))
     {
-        // Set frame time
+        // per-frame time logic
-        GLfloat currentFrame = glfwGetTime();
+        // --------------------
+        float currentFrame = glfwGetTime();
         deltaTime = currentFrame - lastFrame;
         lastFrame = currentFrame;
 
-        // Check and call events
+        // input
-        glfwPollEvents();
+        // -----
-        Do_Movement();
+        processInput(window);
 
-        // Clear buffers
+        // render
+        // ------
         glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-
+        // draw scene as normal
-        // Draw scene as normal
+        shader.use();
-        shader.Use();
         glm::mat4 model;
         glm::mat4 view = camera.GetViewMatrix();
-        glm::mat4 projection = glm::perspective(camera.Zoom, (float)screenWidth / (float)screenHeight, 0.1f, 100.0f);
+        glm::mat4 projection = glm::perspective(camera.Zoom, (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shader.setMat4("model", model);
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
+        shader.setMat4("view", view);
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
+        shader.setMat4("projection", projection);
-        glUniform3f(glGetUniformLocation(shader.Program, "cameraPos"), camera.Position.x, camera.Position.y, camera.Position.z);
+        // cubes
-        // Cubes
         glBindVertexArray(cubeVAO);
-        glBindTexture(GL_TEXTURE_CUBE_MAP, skyboxTexture);
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_2D, cubeTexture);
         glDrawArrays(GL_TRIANGLES, 0, 36);
         glBindVertexArray(0);
 
-        // Draw skybox as last
+        // draw skybox as last
-        glDepthFunc(GL_LEQUAL);  // Change depth function so depth test passes when values are equal to depth buffer's content
+        glDepthFunc(GL_LEQUAL);  // change depth function so depth test passes when values are equal to depth buffer's content
-        skyboxShader.Use();
+        skyboxShader.use();
-        view = glm::mat4(glm::mat3(camera.GetViewMatrix()));	// Remove any translation component of the view matrix
+        view = glm::mat4(glm::mat3(camera.GetViewMatrix())); // remove translation from the view matrix
-        glUniformMatrix4fv(glGetUniformLocation(skyboxShader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
+        skyboxShader.setMat4("view", view);
-        glUniformMatrix4fv(glGetUniformLocation(skyboxShader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
+        skyboxShader.setMat4("projection", projection);
         // skybox cube
         glBindVertexArray(skyboxVAO);
-        glBindTexture(GL_TEXTURE_CUBE_MAP, skyboxTexture);
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexture);
         glDrawArrays(GL_TRIANGLES, 0, 36);
         glBindVertexArray(0);
-        glDepthFunc(GL_LESS); // Set depth function back to default
+        glDepthFunc(GL_LESS); // set depth function back to default
 
-
+        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
-        // Swap the buffers
+        // -------------------------------------------------------------------------------
         glfwSwapBuffers(window);
+        glfwPollEvents();
     }
 
+    // optional: de-allocate all resources once they've outlived their purpose:
+    // ------------------------------------------------------------------------
+    glDeleteVertexArrays(1, &cubeVAO);
+    glDeleteVertexArrays(1, &skyboxVAO);
+    glDeleteBuffers(1, &cubeVBO);
+    glDeleteBuffers(1, &skyboxVAO);
+
     glfwTerminate();
     return 0;
 }
 
-// Loads a cubemap texture from 6 individual texture faces
+// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
-// Order should be:
+// ---------------------------------------------------------------------------------------------------------
-// +X (right)
+void processInput(GLFWwindow *window)
-// -X (left)
-// +Y (top)
-// -Y (bottom)
-// +Z (front)? (CHECK THIS)
-// -Z (back)?
-GLuint loadCubemap(std::vector<std::string> faces)
 {
-    GLuint textureID;
+    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
-    glGenTextures(1, &textureID);
+        glfwSetWindowShouldClose(window, true);
-    glActiveTexture(GL_TEXTURE0);
 
-    int width, height;
+    float cameraSpeed = 2.5 * deltaTime;
-    unsigned char* image;
+    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
-
-    glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);
-    for (GLuint i = 0; i < faces.size(); i++)
-    {
-        image = SOIL_load_image(faces[i].c_str(), &width, &height, 0, SOIL_LOAD_RGB);
-        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
-    }
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
-    glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
-
-    return textureID;
-}
-
-
-// This function loads a texture from file. Note: texture loading functions like these are usually 
-// managed by a 'Resource Manager' that manages all resources (like textures, models, audio). 
-// For learning purposes we'll just define it as a utility function.
-GLuint loadTexture(GLchar const * path)
-{
-    //Generate texture ID and load texture data 
-    GLuint textureID;
-    glGenTextures(1, &textureID);
-    int width, height;
-    unsigned char* image = SOIL_load_image(path, &width, &height, 0, SOIL_LOAD_RGB);
-    // Assign texture to ID
-    glBindTexture(GL_TEXTURE_2D, textureID);
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
-    glGenerateMipmap(GL_TEXTURE_2D);
-
-    // Parameters
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glBindTexture(GL_TEXTURE_2D, 0);
-    SOIL_free_image_data(image);
-    return textureID;
-}
-
-#pragma region "User input"
-
-// Moves/alters the camera positions based on user input
-void Do_Movement()
-{
-    // Camera controls
-    if (keys[GLFW_KEY_W])
         camera.ProcessKeyboard(FORWARD, deltaTime);
-    if (keys[GLFW_KEY_S])
+    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
         camera.ProcessKeyboard(BACKWARD, deltaTime);
-    if (keys[GLFW_KEY_A])
+    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
         camera.ProcessKeyboard(LEFT, deltaTime);
-    if (keys[GLFW_KEY_D])
+    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
         camera.ProcessKeyboard(RIGHT, deltaTime);
 }
 
-// Is called whenever a key is pressed/released via GLFW
+// glfw: whenever the window size changed (by OS or user resize) this callback function executes
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
+// ---------------------------------------------------------------------------------------------
+void framebuffer_size_callback(GLFWwindow* window, int width, int height)
 {
-    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+    // make sure the viewport matches the new window dimensions; note that width and 
-        glfwSetWindowShouldClose(window, GL_TRUE);
+    // height will be significantly larger than specified on retina displays.
-
+    glViewport(0, 0, width, height);
-    if (action == GLFW_PRESS)
-        keys[key] = true;
-    else if (action == GLFW_RELEASE)
-        keys[key] = false;
 }
 
+
+// glfw: whenever the mouse moves, this callback is called
+// -------------------------------------------------------
 void mouse_callback(GLFWwindow* window, double xpos, double ypos)
 {
     if (firstMouse)
@@ -360,8 +316,8 @@ void mouse_callback(GLFWwindow* window, double xpos, double ypos)
         firstMouse = false;
     }
 
-    GLfloat xoffset = xpos - lastX;
+    float xoffset = xpos - lastX;
-    GLfloat yoffset = lastY - ypos;
+    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top
 
     lastX = xpos;
     lastY = ypos;
@@ -369,9 +325,87 @@ void mouse_callback(GLFWwindow* window, double xpos, double ypos)
     camera.ProcessMouseMovement(xoffset, yoffset);
 }
 
+// glfw: whenever the mouse scroll wheel scrolls, this callback is called
+// ----------------------------------------------------------------------
 void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
 {
     camera.ProcessMouseScroll(yoffset);
 }
 
-#pragma endregion
+// utility function for loading a 2D texture from file
+// ---------------------------------------------------
+unsigned int loadTexture(char const * path)
+{
+    unsigned int textureID;
+    glGenTextures(1, &textureID);
+
+    int width, height, nrComponents;
+    unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
+    if (data)
+    {
+        GLenum format;
+        if (nrComponents == 1)
+            format = GL_RED;
+        else if (nrComponents == 3)
+            format = GL_RGB;
+        else if (nrComponents == 4)
+            format = GL_RGBA;
+
+        glBindTexture(GL_TEXTURE_2D, textureID);
+        glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
+        glGenerateMipmap(GL_TEXTURE_2D);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        stbi_image_free(data);
+    }
+    else
+    {
+        std::cout << "Texture failed to load at path: " << path << std::endl;
+        stbi_image_free(data);
+    }
+
+    return textureID;
+}
+
+// loads a cubemap texture from 6 individual texture faces
+// order:
+// +X (right)
+// -X (left)
+// +Y (top)
+// -Y (bottom)
+// +Z (front) 
+// -Z (back)
+// -------------------------------------------------------
+unsigned int loadCubemap(vector<std::string> faces)
+{
+    unsigned int textureID;
+    glGenTextures(1, &textureID);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);
+
+    int width, height, nrComponents;
+    for (unsigned int i = 0; i < faces.size(); i++)
+    {
+        unsigned char *data = stbi_load(faces[i].c_str(), &width, &height, &nrComponents, 0);
+        if (data)
+        {
+            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
+            stbi_image_free(data);
+        }
+        else
+        {
+            std::cout << "Cubemap texture failed to load at path: " << faces[i] << std::endl;
+            stbi_image_free(data);
+        }
+    }
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+
+    return textureID;
+}

src/4.advanced_opengl/6.2.cubemaps_environment_mapping/6.2.cubemaps.fs

@@ -1,7 +1,8 @@
 #version 330 core
+out vec4 FragColor;
+
 in vec3 Normal;
 in vec3 Position;
-out vec4 color;
 
 uniform vec3 cameraPos;
 uniform samplerCube skybox;
@@ -10,5 +11,5 @@ void main()
 {    
     vec3 I = normalize(Position - cameraPos);
     vec3 R = reflect(I, normalize(Normal));
-    color = texture(skybox, R);
+    FragColor = vec4(texture(skybox, R).rgb, 1.0);
 }

src/4.advanced_opengl/6.2.cubemaps_environment_mapping/6.2.cubemaps.vs

@@ -1,6 +1,6 @@
 #version 330 core
-layout (location = 0) in vec3 position;
+layout (location = 0) in vec3 aPos;
-layout (location = 1) in vec3 normal;
+layout (location = 1) in vec3 aNormal;
 
 out vec3 Normal;
 out vec3 Position;
@@ -11,7 +11,7 @@ uniform mat4 projection;
 
 void main()
 {
-    gl_Position = projection * view * model * vec4(position, 1.0f);
+    Normal = mat3(transpose(inverse(model))) * aNormal;
-    Normal = mat3(transpose(inverse(model))) * normal;
+    Position = vec3(model * vec4(aPos, 1.0));
-    Position = vec3(model * vec4(position, 1.0f));
+    gl_Position = projection * view * model * vec4(aPos, 1.0);
 }

src/4.advanced_opengl/6.2.cubemaps_environment_mapping/cubemaps_environment_mapping.cpp

@@ -1,356 +1,311 @@
-// Std. Includes
+#include <glad/glad.h>
-#include <string>
-#include <algorithm>
-using namespace std;
-
-// GLEW
-#define GLEW_STATIC
-#include <GL/glew.h>
-
-// GLFW
 #include <GLFW/glfw3.h>
+#include <stb_image.h>
 
-// GL includes
-#include <learnopengl/shader.h>
-#include <learnopengl/camera.h>
-
-// GLM Mathemtics
 #include <glm/glm.hpp>
 #include <glm/gtc/matrix_transform.hpp>
 #include <glm/gtc/type_ptr.hpp>
 
-// Other Libs
-#include <SOIL.h>
 #include <learnopengl/filesystem.h>
+#include <learnopengl/shader_m.h>
+#include <learnopengl/camera.h>
+#include <learnopengl/model.h>
 
-// Properties
+#include <iostream>
-GLuint screenWidth = 800, screenHeight = 600;
 
-// Function prototypes
+void framebuffer_size_callback(GLFWwindow* window, int width, int height);
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
-void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
 void mouse_callback(GLFWwindow* window, double xpos, double ypos);
-void Do_Movement();
+void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
-GLuint loadTexture(GLchar const * path);
+void processInput(GLFWwindow *window);
-GLuint loadCubemap(std::vector<std::string> faces);
+unsigned int loadTexture(const char *path);
+unsigned int loadCubemap(vector<std::string> faces);
 
-// Camera
+// settings
+const unsigned int SCR_WIDTH = 1280;
+const unsigned int SCR_HEIGHT = 720;
+
+// camera
 Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
-bool keys[1024];
+float lastX = (float)SCR_WIDTH / 2.0;
-GLfloat lastX = 400, lastY = 300;
+float lastY = (float)SCR_HEIGHT / 2.0;
 bool firstMouse = true;
 
-GLfloat deltaTime = 0.0f;
+// timing
-GLfloat lastFrame = 0.0f;
+float deltaTime = 0.0f;
+float lastFrame = 0.0f;
 
-
-
-// The MAIN function, from here we start our application and run our Game loop
 int main()
 {
-    // Init GLFW
+    // glfw: initialize and configure
+    // ------------------------------
     glfwInit();
     glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
     glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
 
-    GLFWwindow* window = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr); // Windowed
+    // glfw window creation
+    // --------------------
+    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
     glfwMakeContextCurrent(window);
-
+    if (window == NULL)
-    // Set the required callback functions
+    {
-    glfwSetKeyCallback(window, key_callback);
+        std::cout << "Failed to create GLFW window" << std::endl;
+        glfwTerminate();
+        return -1;
+    }
+    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
     glfwSetCursorPosCallback(window, mouse_callback);
     glfwSetScrollCallback(window, scroll_callback);
 
-    // Options
+    // tell GLFW to capture our mouse
     glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
 
-    // Initialize GLEW to setup the OpenGL Function pointers
+    // glad: load all OpenGL function pointers
-    glewExperimental = GL_TRUE;
+    // ---------------------------------------
-    glewInit();
+    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
+    {
+        std::cout << "Failed to initialize GLAD" << std::endl;
+        return -1;
+    }
 
-    // Define the viewport dimensions
+    // configure global opengl state
-    glViewport(0, 0, screenWidth, screenHeight);
+    // -----------------------------
-
-    // Setup some OpenGL options
     glEnable(GL_DEPTH_TEST);
-    glDepthFunc(GL_LESS);
 
-    // Setup and compile our shaders
+    // build and compile shaders
-    Shader shader("cubemaps.vs", "cubemaps.frag");
+    // -------------------------
-    Shader skyboxShader("skybox.vs", "skybox.frag");
+    Shader shader("6.2.cubemaps.vs", "6.2.cubemaps.fs");
+    Shader skyboxShader("6.1.skybox.vs", "6.1.skybox.fs");
 
-#pragma region "object_initialization"
+    // set up vertex data (and buffer(s)) and configure vertex attributes
-    // Set the object data (buffers, vertex attributes)
+    // ------------------------------------------------------------------
-    GLfloat cubeVertices[] = {
+    float cubeVertices[] = {
-        // Positions          // Normals
+        // positions          // normals
-        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
-        0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+         0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
-        0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+         0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
-        0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+         0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
-        -0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+        -0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
-        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
 
-        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+        -0.5f, -0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
-        0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+         0.5f, -0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
-        0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+         0.5f,  0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
-        0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+         0.5f,  0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
-        -0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+        -0.5f,  0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
-        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
+        -0.5f, -0.5f,  0.5f,  0.0f,  0.0f, 1.0f,
 
-        -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,
-        -0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f,  0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
-        -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
-        -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
-        -0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f, -0.5f,  0.5f, -1.0f,  0.0f,  0.0f,
-        -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
+        -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,
 
-        0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,
-        0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f,  0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
-        0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
-        0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
-        0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f, -0.5f,  0.5f,  1.0f,  0.0f,  0.0f,
-        0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
+         0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,
 
-        -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,
-        0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
+         0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,
-        0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
+         0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
-        0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
+         0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
-        -0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
+        -0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
-        -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
+        -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,
 
-        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
+        -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,
-        0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
+         0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,
-        0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
+         0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
-        0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
+         0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
-        -0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
+        -0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
-        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f
+        -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f
     };
-    GLfloat skyboxVertices[] = {
+    float skyboxVertices[] = {
-        // Positions          
+        // positions          
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
         -1.0f, -1.0f, -1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        1.0f, 1.0f, -1.0f,
+         1.0f,  1.0f, -1.0f,
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
 
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
         -1.0f, -1.0f, -1.0f,
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
-        -1.0f, 1.0f, 1.0f,
+        -1.0f,  1.0f,  1.0f,
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
 
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        1.0f, -1.0f, 1.0f,
+         1.0f, -1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, -1.0f,
+         1.0f,  1.0f, -1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
 
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
-        -1.0f, 1.0f, 1.0f,
+        -1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, -1.0f, 1.0f,
+         1.0f, -1.0f,  1.0f,
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
 
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
-        1.0f, 1.0f, -1.0f,
+         1.0f,  1.0f, -1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        1.0f, 1.0f, 1.0f,
+         1.0f,  1.0f,  1.0f,
-        -1.0f, 1.0f, 1.0f,
+        -1.0f,  1.0f,  1.0f,
-        -1.0f, 1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
 
         -1.0f, -1.0f, -1.0f,
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        1.0f, -1.0f, -1.0f,
+         1.0f, -1.0f, -1.0f,
-        -1.0f, -1.0f, 1.0f,
+        -1.0f, -1.0f,  1.0f,
-        1.0f, -1.0f, 1.0f
+         1.0f, -1.0f,  1.0f
     };
 
-    // Setup cube VAO
+    // cube VAO
-    GLuint cubeVAO, cubeVBO;
+    unsigned int cubeVAO, cubeVBO;
     glGenVertexArrays(1, &cubeVAO);
     glGenBuffers(1, &cubeVBO);
     glBindVertexArray(cubeVAO);
     glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), &cubeVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
+    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
-    glBindVertexArray(0);
+    // skybox VAO
-    // Setup skybox VAO
+    unsigned int skyboxVAO, skyboxVBO;
-    GLuint skyboxVAO, skyboxVBO;
     glGenVertexArrays(1, &skyboxVAO);
     glGenBuffers(1, &skyboxVBO);
     glBindVertexArray(skyboxVAO);
     glBindBuffer(GL_ARRAY_BUFFER, skyboxVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(skyboxVertices), &skyboxVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
-    glBindVertexArray(0);
 
-#pragma endregion
+    // load textures
+    // -------------
+    vector<std::string> faces
+    {
+        FileSystem::getPath("resources/textures/skybox/right.jpg"),
+        FileSystem::getPath("resources/textures/skybox/left.jpg"),
+        FileSystem::getPath("resources/textures/skybox/top.jpg"),
+        FileSystem::getPath("resources/textures/skybox/bottom.jpg"),
+        FileSystem::getPath("resources/textures/skybox/back.jpg"),
+        FileSystem::getPath("resources/textures/skybox/front.jpg")
+    };
+    unsigned int cubemapTexture = loadCubemap(faces);
 
-    // Cubemap (Skybox)
+    // shader configuration
-    std::vector<std::string> faces;
+    // --------------------
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/right.jpg"));
+    shader.use();
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/left.jpg"));
+    shader.setInt("skybox", 0);
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/top.jpg"));
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/bottom.jpg"));
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/back.jpg"));
-    faces.push_back(FileSystem::getPath("resources/textures/skybox/front.jpg"));
-    GLuint skyboxTexture = loadCubemap(faces);
 
-    // Draw as wireframe
+    skyboxShader.use();
-    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+    skyboxShader.setInt("skybox", 0);
 
-    // Game loop
+    // render loop
+    // -----------
     while (!glfwWindowShouldClose(window))
     {
-        // Set frame time
+        // per-frame time logic
-        GLfloat currentFrame = glfwGetTime();
+        // --------------------
+        float currentFrame = glfwGetTime();
         deltaTime = currentFrame - lastFrame;
         lastFrame = currentFrame;
 
-        // Check and call events
+        // input
-        glfwPollEvents();
+        // -----
-        Do_Movement();
+        processInput(window);
 
-        // Clear buffers
+        // render
+        // ------
         glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-
+        // draw scene as normal
-        // Draw scene as normal
+        shader.use();
-        shader.Use();
         glm::mat4 model;
         glm::mat4 view = camera.GetViewMatrix();
-        glm::mat4 projection = glm::perspective(camera.Zoom, (float)screenWidth / (float)screenHeight, 0.1f, 100.0f);
+        glm::mat4 projection = glm::perspective(camera.Zoom, (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shader.setMat4("model", model);
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
+        shader.setMat4("view", view);
-        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
+        shader.setMat4("projection", projection);
-        glUniform3f(glGetUniformLocation(shader.Program, "cameraPos"), camera.Position.x, camera.Position.y, camera.Position.z);
+        shader.setVec3("cameraPos", camera.Position);
-        // Cubes
+        // cubes
         glBindVertexArray(cubeVAO);
-        glBindTexture(GL_TEXTURE_CUBE_MAP, skyboxTexture);
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexture);
         glDrawArrays(GL_TRIANGLES, 0, 36);
         glBindVertexArray(0);
 
-        // Draw skybox as last
+        // draw skybox as last
-        glDepthFunc(GL_LEQUAL);  // Change depth function so depth test passes when values are equal to depth buffer's content
+        glDepthFunc(GL_LEQUAL);  // change depth function so depth test passes when values are equal to depth buffer's content
-        skyboxShader.Use();
+        skyboxShader.use();
-        view = glm::mat4(glm::mat3(camera.GetViewMatrix()));	// Remove any translation component of the view matrix
+        view = glm::mat4(glm::mat3(camera.GetViewMatrix())); // remove translation from the view matrix
-        glUniformMatrix4fv(glGetUniformLocation(skyboxShader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
+        skyboxShader.setMat4("view", view);
-        glUniformMatrix4fv(glGetUniformLocation(skyboxShader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
+        skyboxShader.setMat4("projection", projection);
         // skybox cube
         glBindVertexArray(skyboxVAO);
-        glBindTexture(GL_TEXTURE_CUBE_MAP, skyboxTexture);
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexture);
         glDrawArrays(GL_TRIANGLES, 0, 36);
         glBindVertexArray(0);
-        glDepthFunc(GL_LESS); // Set depth function back to default
+        glDepthFunc(GL_LESS); // set depth function back to default
 
-
+        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
-        // Swap the buffers
+        // -------------------------------------------------------------------------------
         glfwSwapBuffers(window);
+        glfwPollEvents();
     }
 
+    // optional: de-allocate all resources once they've outlived their purpose:
+    // ------------------------------------------------------------------------
+    glDeleteVertexArrays(1, &cubeVAO);
+    glDeleteVertexArrays(1, &skyboxVAO);
+    glDeleteBuffers(1, &cubeVBO);
+    glDeleteBuffers(1, &skyboxVAO);
+
     glfwTerminate();
     return 0;
 }
 
-// Loads a cubemap texture from 6 individual texture faces
+// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
-// Order should be:
+// ---------------------------------------------------------------------------------------------------------
-// +X (right)
+void processInput(GLFWwindow *window)
-// -X (left)
-// +Y (top)
-// -Y (bottom)
-// +Z (front)? (CHECK THIS)
-// -Z (back)?
-GLuint loadCubemap(std::vector<std::string> faces)
 {
-    GLuint textureID;
+    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
-    glGenTextures(1, &textureID);
+        glfwSetWindowShouldClose(window, true);
-    glActiveTexture(GL_TEXTURE0);
 
-    int width, height;
+    float cameraSpeed = 2.5 * deltaTime;
-    unsigned char* image;
+    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
-
-    glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);
-    for (GLuint i = 0; i < faces.size(); i++)
-    {
-        image = SOIL_load_image(faces[i].c_str(), &width, &height, 0, SOIL_LOAD_RGB);
-        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
-    }
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
-    glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
-
-    return textureID;
-}
-
-
-// This function loads a texture from file. Note: texture loading functions like these are usually 
-// managed by a 'Resource Manager' that manages all resources (like textures, models, audio). 
-// For learning purposes we'll just define it as a utility function.
-GLuint loadTexture(GLchar const * path)
-{
-    //Generate texture ID and load texture data 
-    GLuint textureID;
-    glGenTextures(1, &textureID);
-    int width, height;
-    unsigned char* image = SOIL_load_image(path, &width, &height, 0, SOIL_LOAD_RGB);
-    // Assign texture to ID
-    glBindTexture(GL_TEXTURE_2D, textureID);
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
-    glGenerateMipmap(GL_TEXTURE_2D);
-
-    // Parameters
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glBindTexture(GL_TEXTURE_2D, 0);
-    SOIL_free_image_data(image);
-    return textureID;
-}
-
-#pragma region "User input"
-
-// Moves/alters the camera positions based on user input
-void Do_Movement()
-{
-    // Camera controls
-    if (keys[GLFW_KEY_W])
         camera.ProcessKeyboard(FORWARD, deltaTime);
-    if (keys[GLFW_KEY_S])
+    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
         camera.ProcessKeyboard(BACKWARD, deltaTime);
-    if (keys[GLFW_KEY_A])
+    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
         camera.ProcessKeyboard(LEFT, deltaTime);
-    if (keys[GLFW_KEY_D])
+    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
         camera.ProcessKeyboard(RIGHT, deltaTime);
 }
 
-// Is called whenever a key is pressed/released via GLFW
+// glfw: whenever the window size changed (by OS or user resize) this callback function executes
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
+// ---------------------------------------------------------------------------------------------
+void framebuffer_size_callback(GLFWwindow* window, int width, int height)
 {
-    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+    // make sure the viewport matches the new window dimensions; note that width and 
-        glfwSetWindowShouldClose(window, GL_TRUE);
+    // height will be significantly larger than specified on retina displays.
-
+    glViewport(0, 0, width, height);
-    if (action == GLFW_PRESS)
-        keys[key] = true;
-    else if (action == GLFW_RELEASE)
-        keys[key] = false;
 }
 
+
+// glfw: whenever the mouse moves, this callback is called
+// -------------------------------------------------------
 void mouse_callback(GLFWwindow* window, double xpos, double ypos)
 {
     if (firstMouse)
@@ -360,8 +315,8 @@ void mouse_callback(GLFWwindow* window, double xpos, double ypos)
         firstMouse = false;
     }
 
-    GLfloat xoffset = xpos - lastX;
+    float xoffset = xpos - lastX;
-    GLfloat yoffset = lastY - ypos;
+    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top
 
     lastX = xpos;
     lastY = ypos;
@@ -369,9 +324,87 @@ void mouse_callback(GLFWwindow* window, double xpos, double ypos)
     camera.ProcessMouseMovement(xoffset, yoffset);
 }
 
+// glfw: whenever the mouse scroll wheel scrolls, this callback is called
+// ----------------------------------------------------------------------
 void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
 {
     camera.ProcessMouseScroll(yoffset);
 }
 
-#pragma endregion
+// utility function for loading a 2D texture from file
+// ---------------------------------------------------
+unsigned int loadTexture(char const * path)
+{
+    unsigned int textureID;
+    glGenTextures(1, &textureID);
+
+    int width, height, nrComponents;
+    unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
+    if (data)
+    {
+        GLenum format;
+        if (nrComponents == 1)
+            format = GL_RED;
+        else if (nrComponents == 3)
+            format = GL_RGB;
+        else if (nrComponents == 4)
+            format = GL_RGBA;
+
+        glBindTexture(GL_TEXTURE_2D, textureID);
+        glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
+        glGenerateMipmap(GL_TEXTURE_2D);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        stbi_image_free(data);
+    }
+    else
+    {
+        std::cout << "Texture failed to load at path: " << path << std::endl;
+        stbi_image_free(data);
+    }
+
+    return textureID;
+}
+
+// loads a cubemap texture from 6 individual texture faces
+// order:
+// +X (right)
+// -X (left)
+// +Y (top)
+// -Y (bottom)
+// +Z (front) 
+// -Z (back)
+// -------------------------------------------------------
+unsigned int loadCubemap(vector<std::string> faces)
+{
+    unsigned int textureID;
+    glGenTextures(1, &textureID);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);
+
+    int width, height, nrComponents;
+    for (unsigned int i = 0; i < faces.size(); i++)
+    {
+        unsigned char *data = stbi_load(faces[i].c_str(), &width, &height, &nrComponents, 0);
+        if (data)
+        {
+            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
+            stbi_image_free(data);
+        }
+        else
+        {
+            std::cout << "Cubemap texture failed to load at path: " << faces[i] << std::endl;
+            stbi_image_free(data);
+        }
+    }
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+
+    return textureID;
+}

src/4.advanced_opengl/8.advanced_glsl_ubo/8.advanced_glsl.vs

@@ -1,5 +1,5 @@
 #version 330 core
-layout (location = 0) in vec3 position;
+layout (location = 0) in vec3 aPos;
 
 layout (std140) uniform Matrices
 {
@@ -10,5 +10,5 @@ uniform mat4 model;
 
 void main()
 {
-    gl_Position = projection * view * model * vec4(position, 1.0);
+    gl_Position = projection * view * model * vec4(aPos, 1.0);
 }  

src/4.advanced_opengl/8.advanced_glsl_ubo/8.blue.fs

@@ -1,7 +1,7 @@
 #version 330 core
-out vec4 color;
+out vec4 FragColor;
 
 void main()
 {
-    color = vec4(0.0, 0.0, 1.0, 1.0);
+    FragColor = vec4(0.0, 0.0, 1.0, 1.0);
 }

src/4.advanced_opengl/8.advanced_glsl_ubo/8.green.fs

@@ -1,7 +1,7 @@
 #version 330 core
-out vec4 color;
+out vec4 FragColor;
 
 void main()
 {
-    color = vec4(0.0, 1.0, 0.0, 1.0);
+    FragColor = vec4(0.0, 1.0, 0.0, 1.0);
 }

src/4.advanced_opengl/8.advanced_glsl_ubo/8.red.fs

@@ -1,7 +1,7 @@
 #version 330 core
-out vec4 color;
+out vec4 FragColor;
 
 void main()
 {
-    color = vec4(1.0, 0.0, 0.0, 1.0);
+    FragColor = vec4(1.0, 0.0, 0.0, 1.0);
 }

src/4.advanced_opengl/8.advanced_glsl_ubo/8.yellow.fs

@@ -1,7 +1,7 @@
 #version 330 core
-out vec4 color;
+out vec4 FragColor;
 
 void main()
 {
-    color = vec4(1.0, 1.0, 0.0, 1.0);
+    FragColor = vec4(1.0, 1.0, 0.0, 1.0);
 }

src/4.advanced_opengl/8.advanced_glsl_ubo/advanced_glsl_ubo.cpp

@@ -1,84 +1,90 @@
-// GLEW
+#include <glad/glad.h>
-#define GLEW_STATIC
-#include <GL/glew.h>
-
-// GLFW
 #include <GLFW/glfw3.h>
+#include <stb_image.h>
 
-// GL includes
-#include <learnopengl/shader.h>
-#include <learnopengl/camera.h>
-
-// GLM Mathemtics
 #include <glm/glm.hpp>
 #include <glm/gtc/matrix_transform.hpp>
 #include <glm/gtc/type_ptr.hpp>
 
-// Other Libs
+#include <learnopengl/filesystem.h>
-#include <SOIL.h>
+#include <learnopengl/shader_m.h>
+#include <learnopengl/camera.h>
+#include <learnopengl/model.h>
 
-// Properties
+#include <iostream>
-GLuint screenWidth = 800, screenHeight = 600;
 
-// Function prototypes
+void framebuffer_size_callback(GLFWwindow* window, int width, int height);
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
 void mouse_callback(GLFWwindow* window, double xpos, double ypos);
-void Do_Movement();
+void processInput(GLFWwindow *window);
 
-// Camera
+// settings
+const unsigned int SCR_WIDTH = 1280;
+const unsigned int SCR_HEIGHT = 720;
+
+// camera
 Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
-bool keys[1024];
+float lastX = (float)SCR_WIDTH / 2.0;
-GLfloat lastX = 400, lastY = 300;
+float lastY = (float)SCR_HEIGHT / 2.0;
 bool firstMouse = true;
 
-GLfloat deltaTime = 0.0f;
+// timing
-GLfloat lastFrame = 0.0f;
+float deltaTime = 0.0f;
+float lastFrame = 0.0f;
 
-// The MAIN function, from here we start our application and run our Game loop
 int main()
 {
-    // Init GLFW
+    // glfw: initialize and configure
+    // ------------------------------
     glfwInit();
     glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
     glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
 
-    GLFWwindow* window = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr); // Windowed
+    // glfw window creation
+    // --------------------
+    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
     glfwMakeContextCurrent(window);
-
+    if (window == NULL)
-    // Set the required callback functions
+    {
-    glfwSetKeyCallback(window, key_callback);
+        std::cout << "Failed to create GLFW window" << std::endl;
+        glfwTerminate();
+        return -1;
+    }
+    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
     glfwSetCursorPosCallback(window, mouse_callback);
 
-    // Options
+    // tell GLFW to capture our mouse
     glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
 
-    // Initialize GLEW to setup the OpenGL Function pointers
+    // glad: load all OpenGL function pointers
-    glewExperimental = GL_TRUE;
+    // ---------------------------------------
-    glewInit();
+    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
+    {
+        std::cout << "Failed to initialize GLAD" << std::endl;
+        return -1;
+    }
 
-    // Define the viewport dimensions
+    // configure global opengl state
-    glViewport(0, 0, screenWidth, screenHeight);
+    // -----------------------------
-
-    // Setup some OpenGL options
     glEnable(GL_DEPTH_TEST);
 
-    // Setup and compile our shaders
+    // build and compile shaders
-    Shader shaderRed("uniform_buffers.vs", "red.frag");
+    // -------------------------
-    Shader shaderGreen("uniform_buffers.vs", "green.frag");
+    Shader shaderRed("8.advanced_glsl.vs", "8.red.fs");
-    Shader shaderBlue("uniform_buffers.vs", "blue.frag");
+    Shader shaderGreen("8.advanced_glsl.vs", "8.green.fs");
-    Shader shaderYellow("uniform_buffers.vs", "yellow.frag");
+    Shader shaderBlue("8.advanced_glsl.vs", "8.blue.fs");
+    Shader shaderYellow("8.advanced_glsl.vs", "8.yellow.fs");
     
-    #pragma region "object_initialization"
+    // set up vertex data (and buffer(s)) and configure vertex attributes
-
+    // ------------------------------------------------------------------
-    GLfloat cubeVertices[] = {
+    float cubeVertices[] = {
+        // positions         
         -0.5f, -0.5f, -0.5f, 
-         0.5f,  0.5f, -0.5f,  
          0.5f, -0.5f, -0.5f,  
          0.5f,  0.5f, -0.5f,  
-        -0.5f, -0.5f, -0.5f,  
+         0.5f,  0.5f, -0.5f,  
         -0.5f,  0.5f, -0.5f, 
+        -0.5f, -0.5f, -0.5f, 
 
         -0.5f, -0.5f,  0.5f, 
          0.5f, -0.5f,  0.5f,  
@@ -95,11 +101,11 @@ int main()
         -0.5f,  0.5f,  0.5f, 
 
          0.5f,  0.5f,  0.5f,  
-         0.5f, -0.5f, -0.5f, 
          0.5f,  0.5f, -0.5f,  
          0.5f, -0.5f, -0.5f,  
-         0.5f,  0.5f,  0.5f, 
+         0.5f, -0.5f, -0.5f,  
          0.5f, -0.5f,  0.5f,  
+         0.5f,  0.5f,  0.5f,  
 
         -0.5f, -0.5f, -0.5f, 
          0.5f, -0.5f, -0.5f,  
@@ -109,154 +115,160 @@ int main()
         -0.5f, -0.5f, -0.5f, 
 
         -0.5f,  0.5f, -0.5f, 
-         0.5f,  0.5f,  0.5f,
          0.5f,  0.5f, -0.5f,  
          0.5f,  0.5f,  0.5f,  
+         0.5f,  0.5f,  0.5f,  
+        -0.5f,  0.5f,  0.5f, 
         -0.5f,  0.5f, -0.5f, 
-        -0.5f,  0.5f,  0.5f
     };
-
+    // cube VAO
-    // Setup cube VAO
+    unsigned int cubeVAO, cubeVBO;
-    GLuint cubeVAO, cubeVBO;
     glGenVertexArrays(1, &cubeVAO);
     glGenBuffers(1, &cubeVBO);
     glBindVertexArray(cubeVAO);
     glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), &cubeVertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0); 
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
-    glBindVertexArray(0);
 
-    #pragma endregion
+    // configure a uniform buffer object
-
+    // ---------------------------------
-    // Create a uniform buffer object
+    // first. We get the relevant block indices
-    // First. We get the relevant block indices
+    unsigned int uniformBlockIndexRed = glGetUniformBlockIndex(shaderRed.ID, "Matrices");
-    GLuint uniformBlockIndexRed = glGetUniformBlockIndex(shaderRed.Program, "Matrices");
+    unsigned int uniformBlockIndexGreen = glGetUniformBlockIndex(shaderGreen.ID, "Matrices");
-    GLuint uniformBlockIndexGreen = glGetUniformBlockIndex(shaderGreen.Program, "Matrices");
+    unsigned int uniformBlockIndexBlue = glGetUniformBlockIndex(shaderBlue.ID, "Matrices");
-    GLuint uniformBlockIndexBlue = glGetUniformBlockIndex(shaderBlue.Program, "Matrices");
+    unsigned int uniformBlockIndexYellow = glGetUniformBlockIndex(shaderYellow.ID, "Matrices");
-    GLuint uniformBlockIndexYellow = glGetUniformBlockIndex(shaderYellow.Program, "Matrices");
+    // then we link each shader's uniform block to this uniform binding point
-    // Then we link each shader's uniform block to this uniform binding point
+    glUniformBlockBinding(shaderRed.ID, uniformBlockIndexRed, 0);
-    glUniformBlockBinding(shaderRed.Program, uniformBlockIndexRed, 0);
+    glUniformBlockBinding(shaderGreen.ID, uniformBlockIndexGreen, 0);
-    glUniformBlockBinding(shaderGreen.Program, uniformBlockIndexGreen, 0);
+    glUniformBlockBinding(shaderBlue.ID, uniformBlockIndexBlue, 0);
-    glUniformBlockBinding(shaderBlue.Program, uniformBlockIndexBlue, 0);
+    glUniformBlockBinding(shaderYellow.ID, uniformBlockIndexYellow, 0);
-    glUniformBlockBinding(shaderYellow.Program, uniformBlockIndexYellow, 0);
     // Now actually create the buffer
-    GLuint uboMatrices;
+    unsigned int uboMatrices;
     glGenBuffers(1, &uboMatrices);
     glBindBuffer(GL_UNIFORM_BUFFER, uboMatrices);
     glBufferData(GL_UNIFORM_BUFFER, 2 * sizeof(glm::mat4), NULL, GL_STATIC_DRAW);
     glBindBuffer(GL_UNIFORM_BUFFER, 0);
-    // Define the range of the buffer that links to a uniform binding point
+    // define the range of the buffer that links to a uniform binding point
     glBindBufferRange(GL_UNIFORM_BUFFER, 0, uboMatrices, 0, 2 * sizeof(glm::mat4));
 
-    // Store the projection matrix (we only have to do this once) (note: we're not using zoom anymore by changing the FoV. We only create the projection matrix once now)
+    // store the projection matrix (we only do this once now) (note: we're not using zoom anymore by changing the FoV)
-    glm::mat4 projection = glm::perspective(45.0f, (float)screenWidth/(float)screenHeight, 0.1f, 100.0f);
+    glm::mat4 projection = glm::perspective(45.0f, (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
     glBindBuffer(GL_UNIFORM_BUFFER, uboMatrices);
     glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(glm::mat4), glm::value_ptr(projection));
     glBindBuffer(GL_UNIFORM_BUFFER, 0);
   
-
+    // render loop
-    // Game loop
+    // -----------
-    while(!glfwWindowShouldClose(window))
+    while (!glfwWindowShouldClose(window))
     {
-        // Set frame time
+        // per-frame time logic
-        GLfloat currentFrame = glfwGetTime();
+        // --------------------
+        float currentFrame = glfwGetTime();
         deltaTime = currentFrame - lastFrame;
         lastFrame = currentFrame;
 
-        // Check and call events
+        // input
-        glfwPollEvents();
+        // -----
-        Do_Movement();
+        processInput(window);
 
-        // Clear buffers
+        // render
+        // ------
         glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-        // Set the view and projection matrix in the uniform block - we only have to do this once per loop iteration.
+        // set the view and projection matrix in the uniform block - we only have to do this once per loop iteration.
         glm::mat4 view = camera.GetViewMatrix();
         glBindBuffer(GL_UNIFORM_BUFFER, uboMatrices);
         glBufferSubData(GL_UNIFORM_BUFFER, sizeof(glm::mat4), sizeof(glm::mat4), glm::value_ptr(view));
         glBindBuffer(GL_UNIFORM_BUFFER, 0);
 
-        // Draw 4 cubes 
+        // draw 4 cubes 
         // RED
         glBindVertexArray(cubeVAO);
-        shaderRed.Use();
+        shaderRed.use();
         glm::mat4 model;
-        model = glm::translate(model, glm::vec3(-0.75f, 0.75f, 0.0f));	// Move top-left
+        model = glm::translate(model, glm::vec3(-0.75f, 0.75f, 0.0f)); // move top-left
-        glUniformMatrix4fv(glGetUniformLocation(shaderRed.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shaderRed.setMat4("model", model);
         glDrawArrays(GL_TRIANGLES, 0, 36);
         // GREEN
-        shaderGreen.Use();
+        shaderGreen.use();
         model = glm::mat4();
-        model = glm::translate(model, glm::vec3(0.75f, 0.75f, 0.0f));		// Move top-right
+        model = glm::translate(model, glm::vec3(0.75f, 0.75f, 0.0f)); // move top-right
-        glUniformMatrix4fv(glGetUniformLocation(shaderGreen.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shaderGreen.setMat4("model", model);
-        glDrawArrays(GL_TRIANGLES, 0, 36);        
-        // BLUE
-        shaderBlue.Use();
-        model = glm::mat4();
-        model = glm::translate(model, glm::vec3(-0.75f, -0.75f, 0.0f));	// Move bottom-left
-        glUniformMatrix4fv(glGetUniformLocation(shaderBlue.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
         glDrawArrays(GL_TRIANGLES, 0, 36);
         // YELLOW
-        shaderYellow.Use();
+        shaderYellow.use();
         model = glm::mat4();
-        model = glm::translate(model, glm::vec3(0.75f, -0.75f, 0.0f));	// Move bottom-right
+        model = glm::translate(model, glm::vec3(-0.75f, -0.75f, 0.0f)); // move bottom-left
-        glUniformMatrix4fv(glGetUniformLocation(shaderYellow.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
+        shaderYellow.setMat4("model", model);
+        glDrawArrays(GL_TRIANGLES, 0, 36);
+        // BLUE
+        shaderBlue.use();
+        model = glm::mat4();
+        model = glm::translate(model, glm::vec3(0.75f, -0.75f, 0.0f)); // move bottom-right
+        shaderBlue.setMat4("model", model);
         glDrawArrays(GL_TRIANGLES, 0, 36);
-        glBindVertexArray(0);		
 
-        // Swap the buffers
+        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
+        // -------------------------------------------------------------------------------
         glfwSwapBuffers(window);
+        glfwPollEvents();
     }
 
+    // optional: de-allocate all resources once they've outlived their purpose:
+    // ------------------------------------------------------------------------
+    glDeleteVertexArrays(1, &cubeVAO);
+    glDeleteBuffers(1, &cubeVBO);
+
     glfwTerminate();
     return 0;
 }
-#pragma region "User input"
 
-// Moves/alters the camera positions based on user input
+// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
-void Do_Movement()
+// ---------------------------------------------------------------------------------------------------------
+void processInput(GLFWwindow *window)
 {
-    // Camera controls
+    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
-    if(keys[GLFW_KEY_W])
+        glfwSetWindowShouldClose(window, true);
+
+    float cameraSpeed = 2.5 * deltaTime;
+    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
         camera.ProcessKeyboard(FORWARD, deltaTime);
-    if(keys[GLFW_KEY_S])
+    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
         camera.ProcessKeyboard(BACKWARD, deltaTime);
-    if(keys[GLFW_KEY_A])
+    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
         camera.ProcessKeyboard(LEFT, deltaTime);
-    if(keys[GLFW_KEY_D])
+    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
         camera.ProcessKeyboard(RIGHT, deltaTime);
 }
 
-// Is called whenever a key is pressed/released via GLFW
+// glfw: whenever the window size changed (by OS or user resize) this callback function executes
-void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
+// ---------------------------------------------------------------------------------------------
+void framebuffer_size_callback(GLFWwindow* window, int width, int height)
 {
-    if(key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+    // make sure the viewport matches the new window dimensions; note that width and 
-        glfwSetWindowShouldClose(window, GL_TRUE);
+    // height will be significantly larger than specified on retina displays.
-
+    glViewport(0, 0, width, height);
-    if(action == GLFW_PRESS)
-        keys[key] = true;
-    else if(action == GLFW_RELEASE)
-        keys[key] = false;	
 }
 
+
+// glfw: whenever the mouse moves, this callback is called
+// -------------------------------------------------------
 void mouse_callback(GLFWwindow* window, double xpos, double ypos)
 {
-    if(firstMouse)
+    if (firstMouse)
     {
         lastX = xpos;
         lastY = ypos;
         firstMouse = false;
     }
 
-    GLfloat xoffset = xpos - lastX;
+    float xoffset = xpos - lastX;
-    GLfloat yoffset = lastY - ypos; 
+    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top
 
     lastX = xpos;
     lastY = ypos;
 
     camera.ProcessMouseMovement(xoffset, yoffset);
 }
-
-#pragma endregion