Complete code re-work 'Getting Started' tutorials.

src/1.getting_started/1.1.hello_window/hello_window.cpp

@@ -0,0 +1,74 @@
+#include <glad/glad.h>
+#include <GLFW/glfw3.h>
+
+#include <iostream>
+
+void framebuffer_size_callback(GLFWwindow* window, int width, int height);
+void processInput(GLFWwindow *window);
+
+int main()
+{
+    // 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_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
+
+    // glfw window creation
+    // --------------------
+    GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
+    glfwMakeContextCurrent(window);
+    if (window == NULL)
+    {
+        std::cout << "Failed to create GLFW window" << std::endl;
+        glfwTerminate();
+        return -1;
+    }
+    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
+
+    // glad: load all OpenGL function pointers
+    // ---------------------------------------
+    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
+    {
+        std::cout << "Failed to initialize GLAD" << std::endl;
+        return -1;
+    }    
+
+    // render loop
+    // -----------
+    while (!glfwWindowShouldClose(window))
+    {
+        // input
+        // -----
+        processInput(window);
+
+        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
+        // -------------------------------------------------------------------------------
+        glfwSwapBuffers(window);
+        glfwPollEvents();
+    }
+
+    // glfw: terminate, clearing all previously allocated GLFW resources.
+    // ------------------------------------------------------------------
+    glfwTerminate();
+    return 0;
+}
+
+// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
+// ---------------------------------------------------------------------------------------------------------
+void processInput(GLFWwindow *window)
+{
+    if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
+        glfwSetWindowShouldClose(window, true);
+}
+
+// glfw: whenever the window size changed (by OS or user resize) this callback function executes
+// ---------------------------------------------------------------------------------------------
+void framebuffer_size_callback(GLFWwindow* window, int width, int height)
+{
+    // make sure the viewport matches the new window dimensions; note that width and 
+    // height will be significantly larger than specified on retina displays.
+    glViewport(0, 0, width, height);
+}