正确的方式来扩展org.jbox2d.dynamics.Body

Question

我在想扩展org.jbox2d.dynamics.Body
我已经设置Rectangle延长org.jbox2d.dynamics.Body，并将其设置为DYNAMIC一个问题，但Rectangle不会移动。
如果我创建了多个Rectangle's，它们都位于相同的位置，即（0.0f，0.0f），为什么？

Rectangle定义为：

public class Rectangle extends Shape { 

    private PolygonShape blockShape; 
    private Body body; 
    private float width; 
    private float height; 

    public Rectangle (
     Vec2 centerPoint, 
     float angle, 
     float width, float height, 
     BodyType bt, 
     float density, float friction, float restitution, 
     World world, 
     BodyDef bd){ 

     super(bd,world); 

     this.width = width; 
     this.height = height;    

     blockShape = new PolygonShape(); 
     blockShape.setAsBox(this.width, this.height); 

     FixtureDef fixtureDef = new FixtureDef(); 
     fixtureDef.shape = blockShape; 
     fixtureDef.density = density; 
     fixtureDef.friction = friction; 
     fixtureDef.restitution = restitution; 

     this.bodydef.type = BodyType.DYNAMIC; 
     this.bodydef.position.set(centerPoint.x, centerPoint.y); 
     this.bodydef.angle = angle; 

     world.createBody(this.bodydef); 
     createFixture(fixtureDef); 
     setType(bt); 
    }; 

Shape具有遵循定义：

public abstract class Shape extends org.jbox2d.dynamics.Body{ 
    protected World world; 
    protected BodyDef bodydef; 

    public Shape(BodyDef bd, World w) { 
     super(bd, w); 

     this.world = w; 
     this.bodydef = bd; 
    } 

    protected abstract void update(); 
    protected abstract void draw(GLAutoDrawable gLDrawable); 
} 

在Level.java延伸org.jbox2d.dynamics.World
创建一个Rectangle并调用Rectangle.draw(gLDrawable)

new Rectangle(
     new Vec2(1.0f,1.0f),//Vec2(x,y) 
     0.0f, //angle 
     2.0f, //width 
     2.0f, //height 
     BodyType.DYNAMIC, //bodyType 
     0.5f, //density 
     0.5f, //friction 
     0.5f, //restitution 
     this,    //world 
     new BodyDef()));  //BodyDef 

Answer 1

决定采用org.jbox2d.dynamics.Body

实施例的UserData：

org.jbox2d.dynamics.Body body = level.createBody(bodydef); 
body.setUserData(
    new Shape(parameters) 
);