raylib/docs/examples/web/physac/physics_restitution.c

/*******************************************************************************************
*
*   Physac - Physics restitution
*
*   NOTE 1: Physac requires multi-threading, when InitPhysics() a second thread is created to manage physics calculations.
*   NOTE 2: Physac requires static C library linkage to avoid dependency on MinGW DLL (-static -lpthread)
*
*   Use the following line to compile:
*
*   gcc -o $(NAME_PART).exe $(FILE_NAME) -s $(RAYLIB_DIR)\raylib\raylib_icon -static -lraylib -lpthread 
*   -lglfw3 -lopengl32 -lgdi32 -lopenal32 -lwinmm -std=c99 -Wl,--subsystem,windows -Wl,-allow-multiple-definition
*   
*   Copyright (c) 2017 Victor Fisac
*
********************************************************************************************/

#include "raylib.h"

#define PHYSAC_IMPLEMENTATION
#include "physac.h"

#if defined(PLATFORM_WEB)
    #include <emscripten/emscripten.h>
#endif

//----------------------------------------------------------------------------------
// Global Variables Definition
//----------------------------------------------------------------------------------
int screenWidth = 800;
int screenHeight = 450;

// Physac logo drawing position
int logoX = 0;
int logoY = 15;

PhysicsBody circleA;
PhysicsBody circleB;
PhysicsBody circleC;

//----------------------------------------------------------------------------------
// Module Functions Declaration
//----------------------------------------------------------------------------------
void UpdateDrawFrame(void);     // Update and Draw one frame

//----------------------------------------------------------------------------------
// Main Enry Point
//----------------------------------------------------------------------------------
int main()
{
    // Initialization
    //--------------------------------------------------------------------------------------
    SetConfigFlags(FLAG_MSAA_4X_HINT);
    InitWindow(screenWidth, screenHeight, "Physac [raylib] - Physics restitution");

    // Physac logo drawing position
    logoX = screenWidth - MeasureText("Physac", 30) - 10;

    // Initialize physics and default physics bodies
    InitPhysics();

    // Create ground rectangle physics body
    PhysicsBody ground = CreatePhysicsBodyRectangle((Vector2){ screenWidth/2, screenHeight }, screenWidth, 100, 10);
    ground->enabled = false; // Disable body state to convert it to static (no dynamics, but collisions)
    ground->restitution = 1;

    // Create circles physics body
    circleA = CreatePhysicsBodyCircle((Vector2){ screenWidth*0.25f, screenHeight/2 }, 30, 10);
    circleA->restitution = 0;
    circleB = CreatePhysicsBodyCircle((Vector2){ screenWidth*0.5f, screenHeight/2 }, 30, 10);
    circleB->restitution = 0.5f;
    circleC = CreatePhysicsBodyCircle((Vector2){ screenWidth*0.75f, screenHeight/2 }, 30, 10);
    circleC->restitution = 1;

#if defined(PLATFORM_WEB)
    emscripten_set_main_loop(UpdateDrawFrame, 0, 1);
#else
    SetTargetFPS(60);   // Set our game to run at 60 frames-per-second
    //--------------------------------------------------------------------------------------
    
    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        UpdateDrawFrame();
    }
#endif

    // De-Initialization
    //--------------------------------------------------------------------------------------   
    ClosePhysics();       // Uninitialize physics

    CloseWindow();        // Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}

//----------------------------------------------------------------------------------
// Module Functions Definition
//----------------------------------------------------------------------------------
void UpdateDrawFrame(void)
{
    // Update
    //----------------------------------------------------------------------------------
    if (IsKeyPressed('R'))    // Reset physics input
    {
        // Reset circles physics bodies position and velocity
        circleA->position = (Vector2){ screenWidth*0.25f, screenHeight/2 };
        circleA->velocity = (Vector2){ 0, 0 };
        circleB->position = (Vector2){ screenWidth*0.5f, screenHeight/2 };
        circleB->velocity = (Vector2){ 0, 0 };
        circleC->position = (Vector2){ screenWidth*0.75f, screenHeight/2 };
        circleC->velocity = (Vector2){ 0, 0 };
    }
    //----------------------------------------------------------------------------------

    // 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);

            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
            }
        }

        DrawText("Restitution amount", (screenWidth - MeasureText("Restitution amount", 30))/2, 75, 30, WHITE);
        DrawText("0", circleA->position.x - MeasureText("0", 20)/2, circleA->position.y - 7, 20, WHITE);
        DrawText("0.5", circleB->position.x - MeasureText("0.5", 20)/2, circleB->position.y - 7, 20, WHITE);
        DrawText("1", circleC->position.x - MeasureText("1", 20)/2, circleC->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();
    //----------------------------------------------------------------------------------
}