raylib-src/examples/shapes/shapes_bouncing_ball.c

/*******************************************************************************************
*
*   raylib [shapes] example - bouncing ball
*
*   This example has been created using raylib 1.0 (www.raylib.com)
*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
*
*   Copyright (c) 2013 Ramon Santamaria (@raysan5)
*
********************************************************************************************/

#include "raylib.h"

int main(void)
{
    // Initialization
    //---------------------------------------------------------
    const int screenWidth = 800;
    const int screenHeight = 450;

    InitWindow(screenWidth, screenHeight, "raylib [shapes] example - bouncing ball");

    Vector2 ballPosition = { GetScreenWidth()/2, GetScreenHeight()/2 };
    Vector2 ballSpeed = { 5.0f, 4.0f };
    int ballRadius = 20;

    bool pause = 0;
    int framesCounter = 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 (IsKeyPressed(KEY_SPACE)) pause = !pause;

        if (!pause)
        {
            ballPosition.x += ballSpeed.x;
            ballPosition.y += ballSpeed.y;

            // Check walls collision for bouncing
            if ((ballPosition.x >= (GetScreenWidth() - ballRadius)) || (ballPosition.x <= ballRadius)) ballSpeed.x *= -1.0f;
            if ((ballPosition.y >= (GetScreenHeight() - ballRadius)) || (ballPosition.y <= ballRadius)) ballSpeed.y *= -1.0f;
        }
        else framesCounter++;
        //-----------------------------------------------------

        // Draw
        //-----------------------------------------------------
        BeginDrawing();

            ClearBackground(RAYWHITE);

            DrawCircleV(ballPosition, ballRadius, MAROON);
            DrawText("PRESS SPACE to PAUSE BALL MOVEMENT", 10, GetScreenHeight() - 25, 20, LIGHTGRAY);

            // On pause, we draw a blinking message
            if (pause && ((framesCounter/30)%2)) DrawText("PAUSED", 350, 200, 30, GRAY);

            DrawFPS(10, 10);

        EndDrawing();
        //-----------------------------------------------------
    }

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

    return 0;
}