旋转关节(Revolute Joint)

package{
    import Box2D.Common.Math.b2Vec2;
    import Box2D.Dynamics.b2Body;
    import Box2D.Dynamics.Joints.b2RevoluteJointDef;
    import Box2D.Dynamics.Joints.b2RevoluteJoint;

    /**
    * 旋转关节，指定刚体只能绕着某一个锚点旋转
    */
    public class Main extends BaseMain{

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

        override protected function init():void{
            var bodyA:b2Body=this.createBox(50,50,400,300);
            var bodyB:b2Body=this.createCircle(25,500,300);
            bodyA.SetType(b2Body.b2_staticBody);

            var jointDef:b2RevoluteJointDef=new b2RevoluteJointDef();
            var anchor:b2Vec2=bodyA.GetWorldCenter();
            jointDef.Initialize(bodyA,bodyB,anchor);

            //限制在一个弧度范围内可以转动,,,,,,,,bodyB的位置需要放在bodyA0弧度的位置
            //jointDef.enableLimit=true;
            //jointDef.lowerAngle=45*0.01745;
            //jointDef.upperAngle=135*0.01745;

            //马达速度
            //jointDef.motorSpeed=4;
            //jointDef.maxMotorTorque=400;//必须赋值,否则他的默认值为:0
            //jointDef.enableMotor=true;

            _world.CreateJoint(jointDef);

        }

    };
}

源码下载：http://pan.baidu.com/s/1cmT6oe