import org.jbox2d.dynamics.joints.MouseJointDef; //导入依赖的package包/类
public BlockSpring(PeaWorld peaWorld, World world, float x, float y, float angle) {
  super(peaWorld, peaWorld.getEntityImage("Block-Spring.png"), x, y, angle);

  // add the spring joint
  MouseJointDef mjd = new MouseJointDef();
  mjd.bodyA = world.getBodyList();
  body = initPhysicsBody(world, x, y, angle);
  mjd.bodyB = getBody();
  mjd.target.set(new Vec2(x, y));
  mjd.maxForce = 40f * getBody().getMass();
  mjd.dampingRatio = 0.2f;
  mj = (MouseJoint) world.createJoint(mjd);

  setPos(x, y);
  setAngle(angle);
}
 

import org.jbox2d.dynamics.joints.MouseJointDef; //导入依赖的package包/类
public BlockSpring(PeaWorld peaWorld, World world, float x, float y, float angle) {
  super(peaWorld, x, y, angle);
  
  // add the spring joint
  MouseJointDef mjd = new MouseJointDef();
  mjd.bodyA = world.getBodyList();
  body = initPhysicsBody(world, x, y, angle);
  mjd.bodyB = getBody();
  mjd.target.set(new Vec2(x, y));
  mjd.maxForce = 40f * getBody().getMass();
  mjd.dampingRatio = 0.2f;
  mj = (MouseJoint) world.createJoint(mjd);
  
  setPos(x, y);
  setAngle(angle);
}
 

import org.jbox2d.dynamics.joints.MouseJointDef; //导入依赖的package包/类
public void press(float screen_x, float screen_y) {
  if (query(screen_x, screen_y)) {
    Body body = fixture.getBody();
    MouseJointDef def = new MouseJointDef();
    def.bodyA = world.createBody(new BodyDef());
    def.bodyB = fixture.getBody();
    def.collideConnected = true;
    def.target.set(point);
    def.maxForce = mult_dragforce * body.getMass();
    mouse_joint = (MouseJoint) world.createJoint(def);
    body.setAwake(true);
  }
  active = (mouse_joint != null);
}
 

import org.jbox2d.dynamics.joints.MouseJointDef; //导入依赖的package包/类
public void controlPointCreated(ControlPoint cp) {
	PVector local = transformToLocalSpace(new PVector(cp.getX(), cp.getY()));
	Vec2 pos = getBody().getWorldPoint(new Vec2(local.x, local.y));
	MouseJointDef mouseJointDef = new MouseJointDef();
       mouseJointDef.body1 = getWorld().getGroundBody();
       mouseJointDef.body2 = getBody();
       mouseJointDef.target.set(pos);
       mouseJointDef.maxForce = 100000.0f * getBody().m_mass;
       joints.put(cp, (MouseJoint) getWorld().createJoint(mouseJointDef));
       getBody().wakeUp();
}