滑轮关节(b2PulleyJoint)

 package{
     import Box2D.Collision.b2AABB;
     import Box2D.Collision.b2RayCastInput;
     import Box2D.Collision.b2RayCastOutput;
     import Box2D.Collision.Shapes.b2CircleShape;
     import Box2D.Collision.Shapes.b2PolygonShape;
     import Box2D.Collision.Shapes.b2Shape;
     import Box2D.Common.Math.b2Vec2;
     import Box2D.Dynamics.b2Body;
     import Box2D.Dynamics.b2BodyDef;
     import Box2D.Dynamics.b2Fixture;
     import Box2D.Dynamics.b2FixtureDef;
     import Box2D.Dynamics.b2World;
     import flash.display.Sprite;
     import flash.utils.getTimer;
     import Box2D.Dynamics.Joints.b2PulleyJoint;
     import Box2D.Dynamics.Joints.b2PulleyJointDef;

     /**
     *
     */
     public class Main extends BaseMain{

         public function Main(){
             super(new b2Vec2(0,10));
         }

         override protected function init():void{
             var bodyA:b2Body=this.createBox(50,50,100,400);
             var bodyB:b2Body=this.createCircle(25,700,400);

             var jointDef:b2PulleyJointDef=new b2PulleyJointDef();

             //悬挂的两个点
             var gaA:b2Vec2=new b2Vec2(100/_pixelToMeter,100/_pixelToMeter);
             var gaB:b2Vec2=new b2Vec2(700/_pixelToMeter,100/_pixelToMeter);

             var anchorA:b2Vec2=bodyA.GetWorldCenter();
             var anchorB:b2Vec2=bodyB.GetWorldCenter();
             var r:Number=1;//如果系数是2,那么 length1 的变化会是 length2 的两倍。另外连接 body1 的绳子的约束力将会是连接 body2 绳子的一半。
             jointDef.Initialize(bodyA,bodyB,gaA,gaB,anchorA,anchorB,r);
             var joint:b2PulleyJoint=_world.CreateJoint(jointDef) as b2PulleyJoint;
         }

         override protected function stepBefore():void{ 

         }

     };
 }

源码下载：http://yunpan.cn/c3aI3KPrsUSXy  访问密码 64bc