text: /*******************************************************************************************
  *
  *   raylib [core] example - quat conversions
  *
  *   Generally you should really stick to eulers OR quats...
  *   This tests that various conversions are equivalent.
  *
  *   This example has been created using raylib 3.5 (www.raylib.com)
  *   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
  *
  *   Example contributed by Chris Camacho (@chriscamacho) and reviewed by Ramon Santamaria (@raysan5)
  *
  *   Copyright (c) 2020 Chris Camacho (@chriscamacho) and Ramon Santamaria (@raysan5)
  *
  ********************************************************************************************/
  
  #include "raylib.h"
  
  #include "raymath.h"
  
  int main(void)
  {
      // Initialization
      //--------------------------------------------------------------------------------------
      const int screenWidth = 800;
      const int screenHeight = 450;
  
      InitWindow(screenWidth, screenHeight, "raylib [core] example - quat conversions");
      
      Camera3D camera = { 0 };
      camera.position = (Vector3){ 0.0f, 10.0f, 10.0f };  // Camera position
      camera.target = (Vector3){ 0.0f, 0.0f, 0.0f };      // Camera looking at point
      camera.up = (Vector3){ 0.0f, 1.0f, 0.0f };          // Camera up vector (rotation towards target)
      camera.fovy = 45.0f;                                // Camera field-of-view Y
      camera.type = CAMERA_PERSPECTIVE;                   // Camera mode type
  
      Mesh mesh = GenMeshCylinder(0.2f, 1.0f, 32); 
      Model model = LoadModelFromMesh(mesh);
      
      // Some required variables
      Quaternion q1 = { 0 };
      Matrix m1 = { 0 }, m2 = { 0 }, m3 = { 0 }, m4 = { 0 };
      Vector3 v1 = { 0 }, v2 = { 0 };
  
      SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
      //--------------------------------------------------------------------------------------
     
      // Main game loop
      while (!WindowShouldClose())    // Detect window close button or ESC key
      {
          // Update
          //--------------------------------------------------------------------------------------
          if (!IsKeyDown(KEY_SPACE))
          {
              v1.x += 0.01f;
              v1.y += 0.03f;
              v1.z += 0.05f;
          }
  
          if (v1.x > PI*2) v1.x -= PI*2;
          if (v1.y > PI*2) v1.y -= PI*2;
          if (v1.z > PI*2) v1.z -= PI*2;
          
          q1 = QuaternionFromEuler(v1.x, v1.y, v1.z);
          m1 = MatrixRotateZYX(v1);
          m2 = QuaternionToMatrix(q1);
  
          q1 = QuaternionFromMatrix(m1);
          m3 = QuaternionToMatrix(q1);
          
          v2 = QuaternionToEuler(q1);       
          v2.x *= DEG2RAD; 
          v2.y *= DEG2RAD; 
          v2.z *= DEG2RAD; 
          
          m4 = MatrixRotateZYX(v2);
          //--------------------------------------------------------------------------------------
          
          // Draw
          //----------------------------------------------------------------------------------
          BeginDrawing();
  
              ClearBackground(RAYWHITE);
              
              BeginMode3D(camera);
  
                  model.transform = m1;
                  DrawModel(model, (Vector3){ -1, 0, 0 }, 1.0f, RED);
                  model.transform = m2;
                  DrawModel(model, (Vector3){ 1, 0, 0 }, 1.0f, RED);
                  model.transform = m3;
                  DrawModel(model, (Vector3){ 0, 0, 0 }, 1.0f, RED);
                  model.transform = m4;
                  DrawModel(model, (Vector3){ 0, 0, -1 }, 1.0f, RED);
  
                  DrawGrid(10, 1.0f);
   
              EndMode3D();
          
              if (v2.x < 0) v2.x += PI*2;
              if (v2.y < 0) v2.y += PI*2;
              if (v2.z < 0) v2.z += PI*2;
              
              Color cx,cy,cz;
              cx = cy = cz = BLACK;
              if (v1.x == v2.x) cx = GREEN;
              if (v1.y == v2.y) cy = GREEN;
              if (v1.z == v2.z) cz = GREEN;
              
              DrawText(TextFormat("%2.3f", v1.x), 20, 20, 20, cx);
              DrawText(TextFormat("%2.3f", v1.y), 20, 40, 20, cy);
              DrawText(TextFormat("%2.3f", v1.z), 20, 60, 20, cz);
  
              DrawText(TextFormat("%2.3f", v2.x), 200, 20, 20, cx);
              DrawText(TextFormat("%2.3f", v2.y), 200, 40, 20, cy);
              DrawText(TextFormat("%2.3f", v2.z), 200, 60, 20, cz);
  
          EndDrawing();
          //----------------------------------------------------------------------------------
      }
  
      // De-Initialization
      //--------------------------------------------------------------------------------------
      UnloadModel(model);   // Unload model data (mesh and materials)
      
      CloseWindow();        // Close window and OpenGL context
      //--------------------------------------------------------------------------------------
  
      return 0;
  }
  