问jbox2d教程

EN

    // Static Body
    Vec2  gravity = new Vec2(0,-10);
    World world = new World(gravity);
    BodyDef groundBodyDef = new BodyDef();
    groundBodyDef.position.set(0, -10);
    Body groundBody = world.createBody(groundBodyDef);
    PolygonShape groundBox = new PolygonShape();
    groundBox.setAsBox(50, 10);
    groundBody.createFixture(groundBox, 0);

    // Dynamic Body
    BodyDef bodyDef = new BodyDef();
    bodyDef.type = BodyType.DYNAMIC;
    bodyDef.position.set(0, 4);
    Body body = world.createBody(bodyDef);
    PolygonShape dynamicBox = new PolygonShape();
    dynamicBox.setAsBox(1, 1);
    FixtureDef fixtureDef = new FixtureDef();
    fixtureDef.shape = dynamicBox;
    fixtureDef.density = 1;
    fixtureDef.friction = 0.3f;
    body.createFixture(fixtureDef);

    // Setup world
    float timeStep = 1.0f/60.0f;
    int velocityIterations = 6;
    int positionIterations = 2;

    // Run loop
    for (int i = 0; i < 60; ++i) {
        world.step(timeStep, velocityIterations, positionIterations);
        Vec2 position = body.getPosition();
        float angle = body.getAngle();
        System.out.printf("%4.2f %4.2f %4.2f\n", position.x, position.y, angle);
    }