From 59c4aafb60891b229cb5f09739c464c777059f97 Mon Sep 17 00:00:00 2001
From: Joey de Vries <joey.d.vries@gmail.com>
Date: Tue, 12 May 2020 15:15:57 +0200
Subject: [PATCH] Add camera exercise solutions to repo.

---
 .../7.5.camera_exercise1/camera_exercise1.cpp | 20 +++++++++++
 .../7.5.camera_exercise2/camera_exercise2.cpp | 36 +++++++++++++++++++
 2 files changed, 56 insertions(+)
 create mode 100644 src/1.getting_started/7.5.camera_exercise1/camera_exercise1.cpp
 create mode 100644 src/1.getting_started/7.5.camera_exercise2/camera_exercise2.cpp

diff --git a/src/1.getting_started/7.5.camera_exercise1/camera_exercise1.cpp b/src/1.getting_started/7.5.camera_exercise1/camera_exercise1.cpp
new file mode 100644
index 0000000..c1f203a
--- /dev/null
+++ b/src/1.getting_started/7.5.camera_exercise1/camera_exercise1.cpp
@@ -0,0 +1,20 @@
+// This function is found in the camera class. What we basically do is keep the y position value at 0.0f to force our
+// user to stick to the ground.
+
+[...]
+// processes input received from any keyboard-like input system. Accepts input parameter in the form of camera defined ENUM (to abstract it from windowing systems)
+void ProcessKeyboard(Camera_Movement direction, float deltaTime)
+{
+    float velocity = MovementSpeed * deltaTime;
+    if (direction == FORWARD)
+        Position += Front * velocity;
+    if (direction == BACKWARD)
+        Position -= Front * velocity;
+    if (direction == LEFT)
+        Position -= Right * velocity;
+    if (direction == RIGHT)
+        Position += Right * velocity;
+    // make sure the user stays at the ground level
+    Position.y = 0.0f; // <-- this one-liner keeps the user at the ground level (xz plane)
+}
+[...]
\ No newline at end of file
diff --git a/src/1.getting_started/7.5.camera_exercise2/camera_exercise2.cpp b/src/1.getting_started/7.5.camera_exercise2/camera_exercise2.cpp
new file mode 100644
index 0000000..a8768e8
--- /dev/null
+++ b/src/1.getting_started/7.5.camera_exercise2/camera_exercise2.cpp
@@ -0,0 +1,36 @@
+// Custom implementation of the LookAt function
+glm::mat4 calculate_lookAt_matrix(glm::vec3 position, glm::vec3 target, glm::vec3 worldUp)
+{
+    // 1. Position = known
+    // 2. Calculate cameraDirection
+    glm::vec3 zaxis = glm::normalize(position - target);
+    // 3. Get positive right axis vector
+    glm::vec3 xaxis = glm::normalize(glm::cross(glm::normalize(worldUp), zaxis));
+    // 4. Calculate camera up vector
+    glm::vec3 yaxis = glm::cross(zaxis, xaxis);
+
+    // Create translation and rotation matrix
+    // In glm we access elements as mat[col][row] due to column-major layout
+    glm::mat4 translation = glm::mat4(1.0f); // Identity matrix by default
+    translation[3][0] = -position.x; // Third column, first row
+    translation[3][1] = -position.y;
+    translation[3][2] = -position.z;
+    glm::mat4 rotation = glm::mat4(1.0f);
+    rotation[0][0] = xaxis.x; // First column, first row
+    rotation[1][0] = xaxis.y;
+    rotation[2][0] = xaxis.z;
+    rotation[0][1] = yaxis.x; // First column, second row
+    rotation[1][1] = yaxis.y;
+    rotation[2][1] = yaxis.z;
+    rotation[0][2] = zaxis.x; // First column, third row
+    rotation[1][2] = zaxis.y;
+    rotation[2][2] = zaxis.z; 
+
+    // Return lookAt matrix as combination of translation and rotation matrix
+    return rotation * translation; // Remember to read from right to left (first translation then rotation)
+}
+
+
+// Don't forget to replace glm::lookAt with your own version
+// view = glm::lookAt(glm::vec3(camX, 0.0f, camZ), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
+view = calculate_lookAt_matrix(glm::vec3(camX, 0.0f, camZ), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
\ No newline at end of file