org.jbox2d.dynamics.Body Java Examples

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 float getJointTranslation() {
  Body b1 = m_bodyA;
  Body b2 = m_bodyB;

  Vec2 p1 = pool.popVec2();
  Vec2 p2 = pool.popVec2();
  Vec2 axis = pool.popVec2();
  b1.getWorldPointToOut(m_localAnchorA, p1);
  b2.getWorldPointToOut(m_localAnchorA, p2);
  p2.subLocal(p1);
  b1.getWorldVectorToOut(m_localXAxisA, axis);

  float translation = Vec2.dot(p2, axis);
  pool.pushVec2(3);
  return translation;
}
 

public boolean reportFixture(Fixture fixture) {
  if (m_count == e_maxCount) {
    return false;
  }

  Body body = fixture.getBody();
  Shape shape = fixture.getShape();

  boolean overlap = p.getCollision().testOverlap(shape, 0, m_circle, 0, body.getTransform(),
      m_transform);

  if (overlap) {
    DrawFixture(fixture);
    ++m_count;
  }

  return true;
}
 

@Override
public void step(TestbedSettings settings) {

	super.step(settings);

	for (Body b = getWorld().getBodyList(); b != null; b = b.getNext())
	{
		if (b.getType() != BodyType.DYNAMIC)
		{
			continue;
		}

		Vec2 p = b.getPosition();
		if (p.x <= -10.0f || 10.0f <= p.x || p.y <= 0.0f || 20.0f <= p.y)
		{
			p.x += 0.0;
		}
	}

	addTextLine("Press 'c' to create a circle");
}
 

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 SerializationResult serialize(Joint argJoint, Map<Body, Integer> argBodyIndexMap,
    Map<Joint, Integer> argJointIndexMap) {
  PbJoint.Builder builder = serializeJoint(argJoint, argBodyIndexMap, argJointIndexMap);
  if (builder == null) {
    return null;
  }
  final PbJoint joint = builder.build();
  return new SerializationResult() {
    @Override
    public void writeTo(OutputStream argOutputStream) throws IOException {
      joint.writeTo(argOutputStream);
    }

    @Override
    public Object getValue() {
      return joint;
    }
  };
}
 

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);
}
 

@Override
public void beginContact(Contact cp) {
    // TODO Auto-generated method stub
    Fixture f1 = cp.getFixtureA();
    Fixture f2 = cp.getFixtureB();

    // Get both bodies
    Body b1 = f1.getBody();
    Body b2 = f2.getBody();

    // Get objects that reference these bodies
    Object o1 = b1.getUserData();
    Object o2 = b2.getUserData();

    if ((o1.getClass() == Maze.class && o2.getClass() == Ball.class) || (o1.getClass() == Ball.class && o2.getClass() == Maze.class)) { //if ball touches maze
        balltosurfacecontact(); //play sound
    }

}
 

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

    BodyDef axisDef = new BodyDef();
    axisDef.type = BodyType.STATIC;
    axisDef.position = new Vec2(3, 3);
    Body axis = world.createBody(axisDef);

    CircleShape axisShape = new CircleShape();
    axisShape.setRadius(0.02f);
    axisShape.m_p.set(0, 0);

    //FixtureDef axisFixture = new FixtureDef();
    //axisFixture.shape = axisShape;
    //axis.createFixture(axisFixture);

}
 

public float reportFixture(Fixture fixture, Vec2 point, Vec2 normal, float fraction) {
  Body body = fixture.getBody();
  Object userData = body.getUserData();
  if (userData != null) {
    int index = (Integer) userData;
    if (index == 0) {
      // filter
      return -1f;
    }
  }

  m_hit = true;
  m_point = point;
  m_normal = normal;
  return fraction;
}
 

public float reportFixture(Fixture fixture, Vec2 point, Vec2 normal, float fraction) {
  Body body = fixture.getBody();
  Object userData = body.getUserData();
  if (userData != null) {
    int index = (Integer) userData;
    if (index == 0) {
      // filter
      return -1f;
    }
  }

  m_hit = true;
  m_point = point;
  m_normal = normal;
  return 0f;
}
 

public float reportFixture(Fixture fixture, Vec2 point, Vec2 normal, float fraction) {
  Body body = fixture.getBody();
  int index = 0;
  Object userData = body.getUserData();
  if (userData != null) {
    index = (Integer) userData;
    if (index == 0) {
      // filter
      return -1f;
    }
  }

  assert (m_count < e_maxCount);

  m_points[m_count].set(point);
  m_normals[m_count].set(normal);
  ++m_count;

  if (m_count == e_maxCount) {
    return 0f;
  }

  return 1f;
}
 

private void spawnMouseJoint(Vec2 p) {
  if (mouseJoint != null) {
    return;
  }
  queryAABB.lowerBound.set(p.x - .001f, p.y - .001f);
  queryAABB.upperBound.set(p.x + .001f, p.y + .001f);
  callback.point.set(p);
  callback.fixture = null;
  m_world.queryAABB(callback, queryAABB);

  if (callback.fixture != null) {
    Body body = callback.fixture.getBody();
    MouseJointDef def = new MouseJointDef();
    def.bodyA = groundBody;
    def.bodyB = body;
    def.collideConnected = true;
    def.target.set(p);
    def.maxForce = 1000f * body.getMass();
    mouseJoint = (MouseJoint) m_world.createJoint(def);
    body.setAwake(true);
  }
}
 

@Override
public SerializationResult serialize(Body argBody) {
  PbBody.Builder builder = serializeBody(argBody);
  if (builder == null) {
    return null;
  }
  final PbBody body = builder.build();
  return new SerializationResult() {
    @Override
    public void writeTo(OutputStream argOutputStream) throws IOException {
      body.writeTo(argOutputStream);
    }

    @Override
    public Object getValue() {
      return body;
    }
  };
}
 

public boolean reportFixture(Fixture argFixture) {
  Body body = argFixture.getBody();
  if (body.getType() == BodyType.DYNAMIC) {
    boolean inside = argFixture.testPoint(point);
    if (inside) {
      fixture = argFixture;

      return false;
    }
  }

  return true;
}
 

/**
 * Initialize the bodies, anchors, and reference angle using a world anchor point.
 * 
 * @param bA
 * @param bB
 * @param anchor
 */
public void initialize(Body bA, Body bB, Vec2 anchor) {
  bodyA = bA;
  bodyB = bB;
  bodyA.getLocalPointToOut(anchor, localAnchorA);
  bodyB.getLocalPointToOut(anchor, localAnchorB);
  referenceAngle = bodyB.getAngle() - bodyA.getAngle();
}
 

@Override
public void processBody(Body argBody, Long argTag) {
  if (argTag == BULLET_TAG) {
    m_bullet = argBody;
    return;
  }
  super.processBody(argBody, argTag);
}
 

@Override
public void processBody(Body argBody, Long argTag) {
  if (argTag == CHARACTER_TAG) {
    m_character = argBody;
    return;
  }
  super.processBody(argBody, argTag);
}
 

@Override
public void processBody(Body argBody, Long argTag) {
  if (argTag == CHASSIS_TAG) {
    m_chassis = argBody;
  } else if (argTag == WHEEL_TAG) {
    m_wheel = argBody;
  }
}
 

@Override
public Long getTag(Body argBody) {
  if (argBody == m_chassis) {
    return CHASSIS_TAG;
  } else if (argBody == m_wheel) {
    return WHEEL_TAG;
  }
  return null;
}
 

@Override
public Long getTag(Body argBody) {
  if (argBody == m_bullet) {
    return BULLET_TAG;
  }
  return super.getTag(argBody);
}
 

/**
 * Adds a body to the group
 * 
 * @param argBody
 */
public void addBody(Body argBody) {
  bodies.add(argBody);
  if (bodies.size() == 1) {
    bodyA = argBody;
  }
  if (bodies.size() == 2) {
    bodyB = argBody;
  }
}
 

/**
 * Initialize the bodies, anchors, and reference angle using the world anchor.
 * 
 * @param b1
 * @param b2
 * @param anchor
 */
public void initialize(final Body b1, final Body b2, final Vec2 anchor) {
  bodyA = b1;
  bodyB = b2;
  bodyA.getLocalPointToOut(anchor, localAnchorA);
  bodyB.getLocalPointToOut(anchor, localAnchorB);
  referenceAngle = bodyB.getAngle() - bodyA.getAngle();
}
 

@Override
public void processBody(Body body, Long tag) {
  if (tag == ATTACHMENT_TAG) {
    m_attachment = body;
  } else if (tag == PLATFORM_TAG) {
    m_platform = body;
  } else {
    super.processBody(body, tag);
  }
}
 

@Override
public Long getTag(Body body) {
  if (body == m_attachment)
    return ATTACHMENT_TAG;
  if (body == m_platform)
    return PLATFORM_TAG;
  return super.getTag(body);
}
 

/**
 * Adds a body and the pre-made distance joint. Should only be used for deserialization.
 */
public void addBodyAndJoint(Body argBody, DistanceJoint argJoint) {
  addBody(argBody);
  if (joints == null) {
    joints = new ArrayList<DistanceJoint>();
  }
  joints.add(argJoint);
}
 

@Override
public void processBody(Body body, Long tag) {
  if (tag == BODY_TAG) {
    m_body = body;
  }
  super.processBody(body, tag);
}
 

@Override
public Long getTag(Body body) {
  if (body == m_body) {
    return BODY_TAG;
  }
  return super.getTag(body);
}
 

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);
}
 

/**
 * Initialize the bodies, anchors, lengths, max lengths, and ratio using the world anchors.
 */
public void initialize(Body b1, Body b2, Vec2 ga1, Vec2 ga2, Vec2 anchor1, Vec2 anchor2, float r) {
  bodyA = b1;
  bodyB = b2;
  groundAnchorA = ga1;
  groundAnchorB = ga2;
  localAnchorA = bodyA.getLocalPoint(anchor1);
  localAnchorB = bodyB.getLocalPoint(anchor2);
  Vec2 d1 = anchor1.sub(ga1);
  lengthA = d1.length();
  Vec2 d2 = anchor2.sub(ga2);
  lengthB = d2.length();
  ratio = r;
  assert (ratio > Settings.EPSILON);
}