93 lines
2.8 KiB
C++
Executable File
93 lines
2.8 KiB
C++
Executable File
/*
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* This demo expands on the bouncingball demo to show how you can integrate simple physics to create a
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* more realistic bouncing effect, and bring the ball to a halt
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*/
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#include <libgame/libgame.h>
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int main(int argc, char *argv[])
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{
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Display2D display = Display2D();
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Game &myGame = Game::NewSingleton();
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Animation *anim = NULL;
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Actor ball;
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SpriteStrip *strip = NULL;
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float gravity = 0.1;
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unsigned int lastTimer = 0;
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Vector actorPos;
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Vector actorVel;
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myGame.initSDL();
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myGame.initVideo(640, 480, 32, SDL_HWSURFACE|SDL_DOUBLEBUF);
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display.initVideo((Vector){0,0,0}, 640, 480, 32, SDL_HWSURFACE);
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display.setActive(1);
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myGame.windows.push_back(&display);
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strip = myGame.newSpriteStrip("ball");
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strip->loadFromFile("ball.png", 32, 32, (Vector){0,0,0});
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anim = myGame.newAnimation("ball");
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anim->setStrip(strip, 0, 0, (Vector){0,0,0});
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ball.addAnimation(anim, STATE_DEFAULT);
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ball.setState(STATE_MOVERIGHT | STATE_MOVEUP);
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ball.setPosition((Vector){320,240,0});
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ball.setVelocity((Vector){-1, 0, 0});
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display.addActor(&ball, LAYER_SPRITE1);
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lastTimer = SDL_GetTicks();
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myGame.lockFPS(60);
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while ( 1 ) {
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actorPos = ball.getPosition();
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actorVel = ball.getVelocity();
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/* this is what does the bounce */
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if ( actorPos.y > (480 - ball.nextFrame()->h) ) {
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// if the velocity is low enough, then we just stop the ball so that it will roll
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// smoothly along the floor of the window
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if ( actorVel.y < .01 && actorVel.y > -.01 ) {
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actorVel.y = 0;
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} else {
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// if the velocity is still significant, then we reverse it to create the bounce
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// but since real balls don't bounce quite as high as they did initially, when dropped
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// so we do a primitive modification of the velocity to inroduce something similar to
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// friction physics (see the "physics" demos for ACTUAL physics)
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// The friction numbers here are arbitrary, and were used because they made sense in the
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// demo, you can change the friction for some pretty different effects.
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actorVel.y = -(actorVel.y) - 1;
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// this is friction applied to the X axis to stop the ball's movement eventually
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if ( actorVel.x < .01 && actorVel.x > -.01 ) {
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actorVel.x = 0;
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} else {
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if ( actorVel.x > 0 ) {
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actorVel.x -= .1;
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} else {
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actorVel.x += .1;
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}
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}
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}
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actorPos.y = (480 - ball.nextFrame()->h);
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ball.setPosition(actorPos);
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}
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if ( ((actorPos.x + ball.nextFrame()->w) >= 640) || actorPos.x < 0 ) {
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actorVel.x = -(actorVel.x);
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}
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// -- end of bouncing
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if ( actorPos.x >= 640 ) {
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break;
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}
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if ( (SDL_GetTicks() - lastTimer) >= (1000/30) ) {
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actorVel.y -= gravity;
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ball.setVelocity(actorVel);
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lastTimer = SDL_GetTicks();
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}
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myGame.update();
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if ( myGame.keyHeldDown(SDLK_ESCAPE) ) {
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break;
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}
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myGame.finishFrame();
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}
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return 0;
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}
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