text: /*******************************************************************************************
  *
  *   raylib [physac] example - physics friction
  *
  *   This example has been created using raylib 1.5 (www.raylib.com)
  *   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
  *
  *   This example uses physac 1.1 (https://github.com/raysan5/raylib/blob/master/src/physac.h)
  *
  *   Copyright (c) 2016-2021 Victor Fisac (@victorfisac) and Ramon Santamaria (@raysan5)
  *
  ********************************************************************************************/
  
  #include "raylib.h"
  
  #define PHYSAC_IMPLEMENTATION
  #include "physac.h"
  
  int main(void)
  {
      // Initialization
      //--------------------------------------------------------------------------------------
      const int screenWidth = 800;
      const int screenHeight = 450;
  
      SetConfigFlags(FLAG_MSAA_4X_HINT);
      InitWindow(screenWidth, screenHeight, "raylib [physac] example - physics friction");
  
      // Physac logo drawing position
      int logoX = screenWidth - MeasureText("Physac", 30) - 10;
      int logoY = 15;
  
      // Initialize physics and default physics bodies
      InitPhysics();
  
      // Create floor rectangle physics body
      PhysicsBody floor = CreatePhysicsBodyRectangle((Vector2){ screenWidth/2, screenHeight }, screenWidth, 100, 10);
      floor->enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)
      PhysicsBody wall = CreatePhysicsBodyRectangle((Vector2){ screenWidth/2, screenHeight*0.8f }, 10, 80, 10);
      wall->enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)
  
      // Create left ramp physics body
      PhysicsBody rectLeft = CreatePhysicsBodyRectangle((Vector2){ 25, screenHeight - 5 }, 250, 250, 10);
      rectLeft->enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)
      SetPhysicsBodyRotation(rectLeft, 30*DEG2RAD);
  
      // Create right ramp  physics body
      PhysicsBody rectRight = CreatePhysicsBodyRectangle((Vector2){ screenWidth - 25, screenHeight - 5 }, 250, 250, 10);
      rectRight->enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)
      SetPhysicsBodyRotation(rectRight, 330*DEG2RAD);
  
      // Create dynamic physics bodies
      PhysicsBody bodyA = CreatePhysicsBodyRectangle((Vector2){ 35, screenHeight*0.6f }, 40, 40, 10);
      bodyA->staticFriction = 0.1f;
      bodyA->dynamicFriction = 0.1f;
      SetPhysicsBodyRotation(bodyA, 30*DEG2RAD);
  
      PhysicsBody bodyB = CreatePhysicsBodyRectangle((Vector2){ screenWidth - 35, screenHeight*0.6f }, 40, 40, 10);
      bodyB->staticFriction = 1.0f;
      bodyB->dynamicFriction = 1.0f;
      SetPhysicsBodyRotation(bodyB, 330*DEG2RAD);
  
      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
          //----------------------------------------------------------------------------------
          UpdatePhysics();            // Update physics system
  
          if (IsKeyPressed(KEY_R))    // Reset physics system
          {
              // Reset dynamic physics bodies position, velocity and rotation
              bodyA->position = (Vector2){ 35, screenHeight*0.6f };
              bodyA->velocity = (Vector2){ 0, 0 };
              bodyA->angularVelocity = 0;
              SetPhysicsBodyRotation(bodyA, 30*DEG2RAD);
  
              bodyB->position = (Vector2){ screenWidth - 35, screenHeight*0.6f };
              bodyB->velocity = (Vector2){ 0, 0 };
              bodyB->angularVelocity = 0;
              SetPhysicsBodyRotation(bodyB, 330*DEG2RAD);
          }
          //----------------------------------------------------------------------------------
  
          // Draw
          //----------------------------------------------------------------------------------
          BeginDrawing();
  
              ClearBackground(BLACK);
  
              DrawFPS(screenWidth - 90, screenHeight - 30);
  
              // Draw created physics bodies
              int bodiesCount = GetPhysicsBodiesCount();
              for (int i = 0; i < bodiesCount; i++)
              {
                  PhysicsBody body = GetPhysicsBody(i);
  
                  if (body != NULL)
                  {
                      int vertexCount = GetPhysicsShapeVerticesCount(i);
                      for (int j = 0; j < vertexCount; j++)
                      {
                          // Get physics bodies shape vertices to draw lines
                          // Note: GetPhysicsShapeVertex() already calculates rotation transformations
                          Vector2 vertexA = GetPhysicsShapeVertex(body, j);
  
                          int jj = (((j + 1) < vertexCount) ? (j + 1) : 0);   // Get next vertex or first to close the shape
                          Vector2 vertexB = GetPhysicsShapeVertex(body, jj);
  
                          DrawLineV(vertexA, vertexB, GREEN);     // Draw a line between two vertex positions
                      }
                  }
              }
  
              DrawRectangle(0, screenHeight - 49, screenWidth, 49, BLACK);
  
              DrawText("Friction amount", (screenWidth - MeasureText("Friction amount", 30))/2, 75, 30, WHITE);
              DrawText("0.1", bodyA->position.x - MeasureText("0.1", 20)/2, bodyA->position.y - 7, 20, WHITE);
              DrawText("1", bodyB->position.x - MeasureText("1", 20)/2, bodyB->position.y - 7, 20, WHITE);
  
              DrawText("Press 'R' to reset example", 10, 10, 10, WHITE);
  
              DrawText("Physac", logoX, logoY, 30, WHITE);
              DrawText("Powered by", logoX + 50, logoY - 7, 10, WHITE);
  
          EndDrawing();
          //----------------------------------------------------------------------------------
      }
  
      // De-Initialization
      //--------------------------------------------------------------------------------------
      ClosePhysics();       // Unitialize physics
  
      CloseWindow();        // Close window and OpenGL context
      //--------------------------------------------------------------------------------------
  
      return 0;
  }
  