Rotate camera around scene

src/main.cc

@@ -16,6 +16,7 @@
 
 // SDL
 #include <SDL2/SDL.h>
+#include <SDL2/SDL_timer.h>
 #include <SDL2/SDL_stdinc.h>
 #include <SDL2/SDL_error.h>
 #include <SDL2/SDL_video.h>
@@ -193,29 +194,31 @@ int main() {
 
   glm::vec3 cube_positions[] = {
       glm::vec3( 0.0f,  0.0f,  0.0f), 
-      glm::vec3( 5.0f,  8.0f, -25.0f), 
+      glm::vec3( 4.0f,  6.0f, -15.0f), 
-      glm::vec3(-4.5f, -5.2f, -12.5f),  
+      glm::vec3(-3.5f, -3.2f, -2.5f),  
-      glm::vec3(-6.8f, -5.0f, -22.3f),  
+      glm::vec3(-5.8f, -3.0f, -12.3f),  
-      glm::vec3( 5.4f, -3.4f, -13.5f),  
+      glm::vec3( 4.4f, -1.4f, -3.5f),  
-      glm::vec3(-4.7f,  6.0f, -17.5f),  
+      glm::vec3(-3.7f,  4.0f, -7.5f),  
-      glm::vec3( 4.3f, -5.0f, -12.5f),  
+      glm::vec3( 3.3f, -3.0f, -2.5f),  
-      glm::vec3( 4.5f,  5.0f, -12.5f), 
+      glm::vec3( 3.5f,  3.0f, -2.5f), 
-      glm::vec3( 4.5f,  3.2f, -11.5f), 
+      glm::vec3( 3.5f,  1.2f, -1.5f), 
-      glm::vec3(-4.3f,  4.0f, -11.5f)  
+      glm::vec3(-3.3f,  2.0f, -1.5f)  
   };
 
+  glm::vec3 camera_target    = glm::vec3(0.0f, 0.0f, 0.0f);
+  glm::vec3 world_up         = glm::vec3(0.0f, 1.0f, 0.0f);
+
   glm::mat4 model      = glm::mat4(1.0f);
-
   glm::mat4 view       = glm::mat4(1.0f);
-  view = glm::translate(view, glm::vec3(0.0f, 0.0f, -4.0f));
-
   glm::mat4 projection = glm::perspective(glm::radians(45.0f), (float)WINDOW_WIDTH / (float)WINDOW_HEIGHT, 0.1f, 100.0f);
 
-  glUniformMatrix4fv(glGetUniformLocation(main_shader.program, "view"), 1, GL_FALSE, glm::value_ptr(view));
   glUniformMatrix4fv(glGetUniformLocation(main_shader.program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
 
+  float ticks        = 0;
+  float radius       = 10.0f;
   bool running       = true;
   SDL_Event event    = {};
+
   while (running) {
     while (SDL_PollEvent(&event)) {
       switch (event.type) {
@@ -250,6 +253,13 @@ int main() {
                          0.0f : texture_mix_factor > 1.0f ?
                          1.0f : texture_mix_factor;
 
+    ticks                     = (float)SDL_GetTicks() / 1000.0f;
+    float camera_x            = sin(ticks) * radius;
+    float camera_z            = cos(ticks) * radius;
+    glm::vec3 camera_position = glm::vec3(camera_x, 0.0f, camera_z);
+    view                      = glm::lookAt(camera_position, camera_target, world_up);
+    glUniformMatrix4fv(glGetUniformLocation(main_shader.program, "view"), 1, GL_FALSE, glm::value_ptr(view));
+
     glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);