绳关节(b2RopeJoint)

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;

    import Box2D.Dynamics.Joints.b2RopeJointDef;

    import Box2D.Dynamics.Joints.b2RopeJoint;

    //出现脱节时，调velocityIterations, positionIterations

    //_world.Step(1/30,128,128);

    public class Main extends BaseMain{

        public function Main(){

            super(new b2Vec2(0,10));

        }

        private const ropeW:Number=20;

        private const ropeH:Number=20;

        override protected function init():void{

            var bodies:Vector.<b2Body>=new Vector.<b2Body>();

            var i:int;

            for(i=0;i<10;i++){

                var body:b2Body=createBox(ropeW,ropeH,400+i*ropeW,100);

                bodies[i]=body;

                if(i>0){

                    var bodyA:b2Body=bodies[i-1];

                    var bodyB:b2Body=bodies[i];

                    var halfW:Number=ropeW*0.5/_ptm_ratio;

                    var anchorA:b2Vec2=new b2Vec2(bodyA.GetPosition().x+halfW,bodyA.GetPosition().y);

                    var anchorB:b2Vec2=new b2Vec2(bodyB.GetPosition().x-halfW,bodyB.GetPosition().y);

                    var maxLength:Number=0.1;

                    createRopeJoint(bodyA,bodyB,anchorA,anchorB,maxLength);

                }

            }

            bodies[0].SetType(b2Body.b2_staticBody);

            var bigBox:b2Body=createBox(400,400,400+i*ropeW,100);

            bigBox.SetSensor(true);

            createRopeJoint(bodies[bodies.length-1],bigBox,

                            new b2Vec2(bodies[bodies.length-1].GetPosition().x+halfW,bodies[bodies.length-1].GetPosition().y),//anchorA

                            new b2Vec2(bigBox.GetPosition().x-200/_ptm_ratio,bigBox.GetPosition().y),//anchorB

                            0.1);//maxLength

        }

        private function createRopeJoint(bodyA:b2Body,bodyB:b2Body,anchorA:b2Vec2,anchorB:b2Vec2,maxLength:Number):void{

            var jointDef:b2RopeJointDef=new b2RopeJointDef();

            jointDef.Initialize(bodyA,bodyB,anchorA,anchorB,maxLength);

            jointDef.length=5;

            b2RopeJoint(_world.CreateJoint(jointDef));

        }

        override protected function stepBefore():void{

        }

    };

}

源码下载：http://pan.baidu.com/s/1jIjpjIu