Java Code Examples for org.jbox2d.dynamics.Body#createFixture()

private void updateTopAndBottomBounds() {
    BodyDef bodyDef = new BodyDef();
    bodyDef.type = BodyType.STATIC;

    PolygonShape shape = new PolygonShape();
    float hx = mappingView2Body(width);
    float hy = mappingView2Body(proportion);
    shape.setAsBox(hx, hy);

    FixtureDef def = new FixtureDef();
    def.shape = shape;
    def.density = density;
    def.friction = frictionRatio;
    def.restitution = restitutionRatio;

    bodyDef.position.set(0, -hy);
    Body topBody = world.createBody(bodyDef);
    topBody.createFixture(def);

    bodyDef.position.set(0, mappingView2Body(height) + hy);
    Body bottomBody = world.createBody(bodyDef);
    bottomBody.createFixture(def);
}
 

public void createCircle()
{
	float radius = 2.0f;
	CircleShape shape = new CircleShape();
	shape.m_p.setZero();
	shape.m_radius = radius;

	FixtureDef fd = new FixtureDef();
	fd.shape = shape;
	fd.density = 1.0f;
	fd.friction = 0.0f;

	Vec2 p = new Vec2((float)Math.random(), 3.0f + (float)Math.random());
	BodyDef bd = new BodyDef();
	bd.type = BodyType.DYNAMIC;
	bd.position = p;
	//bd.allowSleep = false;
	Body body = getWorld().createBody(bd);

	body.createFixture(fd);
}
 

public void makeDomino(float x, float y, boolean horizontal, World world) {

    PolygonShape sd = new PolygonShape();
    sd.setAsBox(.5f * dwidth, .5f * dheight);
    FixtureDef fd = new FixtureDef();
    fd.shape = sd;
    fd.density = ddensity;
    BodyDef bd = new BodyDef();
    bd.type = BodyType.DYNAMIC;
    fd.friction = dfriction;
    fd.restitution = 0.65f;
    bd.position = new Vec2(x, y);
    bd.angle = horizontal ? (float) (Math.PI / 2.0) : 0f;
    Body myBody = getWorld().createBody(bd);
    myBody.createFixture(fd);
  }
 

@Override
public synchronized void step(TestbedSettings settings) {
  super.step(settings);

  if (m_count < MAX_NUM) {
    BodyDef bd = new BodyDef();
    bd.type = BodyType.DYNAMIC;
    bd.position.set(0.0f, 10.0f);
    Body body = m_world.createBody(bd);

    PolygonShape shape = new PolygonShape();
    shape.setAsBox(0.125f, 0.125f);
    body.createFixture(shape, 1.0f);

    ++m_count;
  }
}
 

public Fixture deserializeFixture(Body argBody, PbFixture argFixture) {
  PbFixture f = argFixture;

  FixtureDef fd = new FixtureDef();
  fd.density = f.getDensity();
  fd.filter.categoryBits = f.getFilter().getCategoryBits();
  fd.filter.groupIndex = f.getFilter().getGroupIndex();
  fd.filter.maskBits = f.getFilter().getMaskBits();
  fd.friction = f.getFriction();
  fd.isSensor = f.getSensor();
  fd.restitution = f.getRestitution();
  fd.shape = deserializeShape(f.getShape());

  Fixture fixture = argBody.createFixture(fd);
  if (listener != null && f.hasTag()) {
    listener.processFixture(fixture, f.getTag());
  }
  return fixture;
}
 

private void updateLeftAndRightBounds() {
    BodyDef bodyDef = new BodyDef();
    //生成静态刚体
    bodyDef.type = BodyType.STATIC;

    //设置形状 - 多边形
    PolygonShape shape = new PolygonShape();

    //hx 1  hy 屏幕高度
    float hx = mappingView2Body(proportion);
    float hy = mappingView2Body(height);
    shape.setAsBox(hx, hy);

    //设置 系数
    FixtureDef def = new FixtureDef();
    def.shape = shape;
    def.density = density;
    def.friction = frictionRatio;
    def.restitution = restitutionRatio;

    //-1 高度
    bodyDef.position.set(-hx, hy);
    Body leftBody = world.createBody(bodyDef);
    //设置位置
    leftBody.createFixture(def);

    //这里便于理解 应该是 w + 1  h
    //而不是 w + 1 0 验证结果一样
    bodyDef.position.set(mappingView2Body(width) + hx, 0);
    Body rightBody = world.createBody(bodyDef);
    rightBody.createFixture(def);
}
 

private void createBody(View childView) {
    BodyDef bodyDef = new BodyDef();
    bodyDef.type = BodyType.DYNAMIC;

    //设置view中心点位置
    bodyDef.position.set(mappingView2Body(childView.getX() + childView.getWidth() / 2),
            mappingView2Body(childView.getY() + childView.getHeight() / 2));

    Shape shape = null;
    Boolean isCircle = (boolean) childView.getTag(R.id.wd_view_circle_tag);
    if (isCircle != null && isCircle) {
        shape = createCircleBody(childView);
    } else {
        shape = createPolygonBody(childView);
    }

    //设置系数
    FixtureDef def = new FixtureDef();
    def.shape = shape;
    def.density = density;
    def.friction = frictionRatio;
    def.restitution = restitutionRatio;

    Body body = world.createBody(bodyDef);
    body.createFixture(def);

    childView.setTag(R.id.wd_view_body_tag, body);
    body.setLinearVelocity(new Vec2(random.nextFloat(), random.nextFloat()));
}
 

private Box2d() {
  // Define the gravity vector.
  Vec2 gravity = new Vec2(0f, -9.8f);

  // Initialise the World.
  world = new World(gravity);

  // Create the ground (Something for dynamic bodies to collide with).
  {
    BodyDef groundBodyDef = new BodyDef();
    groundBodyDef.position.set(10, -40);
    groundBodyDef.type = BodyType.STATIC;

    // Create the Body in the World.
    Body ground = world.createBody(groundBodyDef);

    // Create the fixtures (physical aspects) of the ground body.
    FixtureDef groundEdgeFixtureDef = new FixtureDef();
    groundEdgeFixtureDef.density = 1.0f;
    groundEdgeFixtureDef.friction = 1.0f;
    groundEdgeFixtureDef.restitution = 0.4f;

    PolygonShape groundEdge = new PolygonShape();
    groundEdgeFixtureDef.shape = groundEdge;

    // Bottom Edge.
    groundEdge.setAsBox(100, 1);
    ground.createFixture(groundEdgeFixtureDef);
  }

  for (int i = 0; i < NUM_BALLS; i++) {
    spawnBall();
  }
}
 

private void spawnBall() {
  float dx = (float) Math.random() * 10f;
  float dy = (float) Math.random() * 10f - 5f;
  // Create a Ball.
  BodyDef ballBodyDef = new BodyDef();
  ballBodyDef.type = BodyType.DYNAMIC;
  ballBodyDef.position.set(5 + dx, 5 + dy); // Centre of the ground box.

  // Create the body for the ball within the World.
  Body ball = world.createBody(ballBodyDef);

  float radius = 0.5f + (float) Math.random();

  // Create the actual fixture representing the box.
  CircleShape ballShape = new CircleShape();
  ballShape.m_radius = radius; // Diameter of 1m.
  // ballShape.m_p is the offset relative to body. Default of (0,0)

  FixtureDef ballFixtureDef = new FixtureDef();
  ballFixtureDef.density = 1.0f; // Must have a density or else it won't
  // be affected by gravity.
  ballFixtureDef.restitution = 0.4f; // Define how bouncy the ball is.
  ballFixtureDef.friction = 0.2f;
  ballFixtureDef.shape = ballShape;

  // Add the fixture to the ball body.
  ball.createFixture(ballFixtureDef);
}
 

private void initBalls() {
    final float ballRadius = 0.15f;

    final BodyDef ballDef = new BodyDef();
    ballDef.type = BodyType.DYNAMIC;
    final FixtureDef fixtureDef = new FixtureDef();
    fixtureDef.friction = 0.3f;
    fixtureDef.restitution = 0.3f;
    fixtureDef.density = 0.2f;
    final CircleShape shape = new CircleShape();
    shape.m_radius = ballRadius;
    fixtureDef.shape = shape;

    for (int i = 0; i < 6; ++i) {
        for (int j = 0; j < 6; ++j) {
            final float x = (j + 0.5f) * (ballRadius * 2 + 0.01f);
            final float y = (i + 0.5f) * (ballRadius * 2 + 0.01f);
            ballDef.position.x = 3 + x;
            ballDef.position.y = 3 + y;
            Body body = world.createBody(ballDef);
            body.createFixture(fixtureDef);

            ballDef.position.x = 3 - x;
            ballDef.position.y = 3 + y;
            body = world.createBody(ballDef);
            body.createFixture(fixtureDef);

            ballDef.position.x = 3 + x;
            ballDef.position.y = 3 - y;
            body = world.createBody(ballDef);
            body.createFixture(fixtureDef);

            ballDef.position.x = 3 - x;
            ballDef.position.y = 3 - y;
            body = world.createBody(ballDef);
            body.createFixture(fixtureDef);
        }
    }
}
 

private void initBalls() {
    float ballRadius = 0.15f;

    BodyDef ballDef = new BodyDef();
    ballDef.type = BodyType.DYNAMIC;
    FixtureDef fixtureDef = new FixtureDef();
    fixtureDef.friction = 0.3f;
    fixtureDef.restitution = 0.3f;
    fixtureDef.density = 0.2f;
    CircleShape shape = new CircleShape();
    shape.m_radius = ballRadius;
    fixtureDef.shape = shape;

    for (int i = 0; i < 5; ++i) {
        for (int j = 0; j < 5; ++j) {
            float x = (j + 0.5f) * (ballRadius * 2 + 0.01f);
            float y = (i + 0.5f) * (ballRadius * 2 + 0.01f);
            ballDef.position.x = 3 + x;
            ballDef.position.y = 3 + y;
            Body body = world.createBody(ballDef);
            body.createFixture(fixtureDef);

            ballDef.position.x = 3 - x;
            ballDef.position.y = 3 + y;
            body = world.createBody(ballDef);
            body.createFixture(fixtureDef);

            ballDef.position.x = 3 + x;
            ballDef.position.y = 3 - y;
            body = world.createBody(ballDef);
            body.createFixture(fixtureDef);

            ballDef.position.x = 3 - x;
            ballDef.position.y = 3 - y;
            body = world.createBody(ballDef);
            body.createFixture(fixtureDef);
        }
    }
}
 

@Test
public void testSimpleBall() {
    World world = new World(new Vec2(0, -9.8f));

    float ballRadius = 0.15f;

    BodyDef ballDef = new BodyDef();
    ballDef.type = BodyType.DYNAMIC;
    FixtureDef fixtureDef = new FixtureDef();
    fixtureDef.friction = 0.3f;
    fixtureDef.restitution = 0.3f;
    fixtureDef.density = 0.2f;
    CircleShape shape = new CircleShape();
    shape.m_radius = ballRadius;
    fixtureDef.shape = shape;

    int i=0;
    int j=0;

    float x = (j + 0.5f) * (ballRadius * 2 + 0.01f);
    float y = (i + 0.5f) * (ballRadius * 2 + 0.01f);
    ballDef.position.x = 3 + x;
    ballDef.position.y = 3 + y;
    Body theBall = world.createBody(ballDef);
    theBall.createFixture(fixtureDef);

    for (int k=0;k<100;k++) {
        world.step(0.01f, 20, 40);
    }

    Vec2 thePosition = theBall.getPosition();
    int theX = (int)(thePosition.x * 1000);
    int theY = (int) (thePosition.y * 1000);

    System.out.println("Finally ended at ");
    System.out.println(theX);
    System.out.println(theY);
}
 

void Break() {
  // Create two bodies from one.
  Body body1 = m_piece1.getBody();
  Vec2 center = body1.getWorldCenter();

  body1.destroyFixture(m_piece2);
  m_piece2 = null;

  BodyDef bd = new BodyDef();
  bd.type = BodyType.DYNAMIC;
  bd.position = body1.getPosition();
  bd.angle = body1.getAngle();

  Body body2 = getWorld().createBody(bd);
  m_piece2 = body2.createFixture(m_shape2, 1.0f);

  // Compute consistent velocities for new bodies based on
  // cached velocity.
  Vec2 center1 = body1.getWorldCenter();
  Vec2 center2 = body2.getWorldCenter();

  Vec2 velocity1 = m_velocity.add(Vec2.cross(m_angularVelocity, center1.sub(center)));
  Vec2 velocity2 = m_velocity.add(Vec2.cross(m_angularVelocity, center2.sub(center)));

  body1.setAngularVelocity(m_angularVelocity);
  body1.setLinearVelocity(velocity1);

  body2.setAngularVelocity(m_angularVelocity);
  body2.setLinearVelocity(velocity2);
}
 

@Override
public void initTest(boolean deserialized) {
  {
    BodyDef bd = new BodyDef();
    bd.type = BodyType.DYNAMIC;
    bd.allowSleep = false;
    bd.position.set(0.0f, 10.0f);
    Body body = m_world.createBody(bd);

    PolygonShape shape = new PolygonShape();
    shape.setAsBox(0.5f, 10.0f, new Vec2(10.0f, 0.0f), 0.0f);
    body.createFixture(shape, 5.0f);
    shape.setAsBox(0.5f, 10.0f, new Vec2(-10.0f, 0.0f), 0.0f);
    body.createFixture(shape, 5.0f);
    shape.setAsBox(10.0f, 0.5f, new Vec2(0.0f, 10.0f), 0.0f);
    body.createFixture(shape, 5.0f);
    shape.setAsBox(10.0f, 0.5f, new Vec2(0.0f, -10.0f), 0.0f);
    body.createFixture(shape, 5.0f);

    RevoluteJointDef jd = new RevoluteJointDef();
    jd.bodyA = getGroundBody();
    jd.bodyB = body;
    jd.localAnchorA.set(0.0f, 10.0f);
    jd.localAnchorB.set(0.0f, 0.0f);
    jd.referenceAngle = 0.0f;
    jd.motorSpeed = 0.05f * MathUtils.PI;
    jd.maxMotorTorque = 1e8f;
    jd.enableMotor = true;
    m_joint = (RevoluteJoint) m_world.createJoint(jd);
  }
  m_count = 0;
}
 

@Override
public void initTest(boolean deserialized) {
  if (deserialized) {
    return;
  }
  // Ground body
  {
    EdgeShape shape = new EdgeShape();
    shape.set(new Vec2(-50.0f, 0.0f), new Vec2(50.0f, 0.0f));

    FixtureDef sd = new FixtureDef();
    sd.shape = shape;

    BodyDef bd = new BodyDef();
    Body ground = getWorld().createBody(bd);
    ground.createFixture(sd);
  }

  float xLo = -5.0f, xHi = 5.0f;
  float yLo = 2.0f, yHi = 35.0f;

  // Small triangle
  Vec2 vertices[] = new Vec2[3];
  vertices[0] = new Vec2(-1.0f, 0.0f);
  vertices[1] = new Vec2(1.0f, 0.0f);
  vertices[2] = new Vec2(0.0f, 2.0f);

  PolygonShape polygon = new PolygonShape();
  polygon.set(vertices, 3);

  FixtureDef triangleShapeDef = new FixtureDef();
  triangleShapeDef.shape = polygon;
  triangleShapeDef.density = 1.0f;

  BodyDef triangleBodyDef = new BodyDef();
  triangleBodyDef.type = BodyType.DYNAMIC;
  triangleBodyDef.position.set(MathUtils.randomFloat(xLo, xHi), MathUtils.randomFloat(yLo, yHi));

  Body body1 = getWorld().createBody(triangleBodyDef);
  body1.createFixture(triangleShapeDef);

  // Large triangle (recycle definitions)
  vertices[0].mulLocal(2.0f);
  vertices[1].mulLocal(2.0f);
  vertices[2].mulLocal(2.0f);
  polygon.set(vertices, 3);

  triangleBodyDef.position.set(MathUtils.randomFloat(xLo, xHi), MathUtils.randomFloat(yLo, yHi));

  Body body2 = getWorld().createBody(triangleBodyDef);
  body2.createFixture(triangleShapeDef);

  // Small box
  polygon.setAsBox(1.0f, 0.5f);

  FixtureDef boxShapeDef = new FixtureDef();
  boxShapeDef.shape = polygon;
  boxShapeDef.density = 1.0f;

  BodyDef boxBodyDef = new BodyDef();
  boxBodyDef.type = BodyType.DYNAMIC;
  boxBodyDef.position.set(MathUtils.randomFloat(xLo, xHi), MathUtils.randomFloat(yLo, yHi));

  Body body3 = getWorld().createBody(boxBodyDef);
  body3.createFixture(boxShapeDef);

  // Large box (recycle definitions)
  polygon.setAsBox(2.0f, 1.0f);
  boxBodyDef.position.set(MathUtils.randomFloat(xLo, xHi), MathUtils.randomFloat(yLo, yHi));

  Body body4 = getWorld().createBody(boxBodyDef);
  body4.createFixture(boxShapeDef);

  // Small circle
  CircleShape circle = new CircleShape();
  circle.m_radius = 1.0f;

  FixtureDef circleShapeDef = new FixtureDef();
  circleShapeDef.shape = circle;
  circleShapeDef.density = 1.0f;

  BodyDef circleBodyDef = new BodyDef();
  circleBodyDef.type = BodyType.DYNAMIC;
  circleBodyDef.position.set(MathUtils.randomFloat(xLo, xHi), MathUtils.randomFloat(yLo, yHi));

  Body body5 = getWorld().createBody(circleBodyDef);
  body5.createFixture(circleShapeDef);

  // Large circle
  circle.m_radius *= 2.0f;
  circleBodyDef.position.set(MathUtils.randomFloat(xLo, xHi), MathUtils.randomFloat(yLo, yHi));

  Body body6 = getWorld().createBody(circleBodyDef);
  body6.createFixture(circleShapeDef);
}