Actionscript 3 为box2D世界对象创建边界

我用box2D制作了物理效果，下面是我的代码集

    public class Main extends SpriteVisualElement
    {

        public var world:b2World;
        public var wheelArray:Array;
        public var stepTimer:Timer;
        public var scaleFactor:Number = 20; 

        public function Main()
        {
            if (stage) 
                init();
            else 
                addEventListener(Event.ADDED_TO_STAGE, init);
        }

        private function init(e:Event = null):void
        {
            removeEventListener(Event.ADDED_TO_STAGE, init);
            getStarted();
        }

        private function getStarted():void
        {
            var gravity:b2Vec2 = new b2Vec2(0, 10);
            world = new b2World(gravity, true);
            wheelArray = new Array();

            for (var i:int = 0; i < 20; i++)
            {
                createWheel(
                    Math.random() * 0.5,
                    Math.random() * (stage.stageWidth - 20) + 10,
                    Math.random() * (stage.stageHeight - 20) + 10,
                    (Math.random() * 100) - 50,
                    0
                );
            }

            createBoundaries();

            stepTimer = new Timer(0.025 * 1000);
            stepTimer.addEventListener(TimerEvent.TIMER, onTick);
            graphics.lineStyle(3, 0xff0000);
            stepTimer.start();
        }

        private function createBoundaries():void
        {
            trace(this.height,this.width,stage.height,stage.width);
            // need some code here

        }

        protected function onTick(event:TimerEvent):void
        {
            graphics.clear();
            graphics.lineStyle(3, 0xff0000);
            world.Step(0.025, 10, 10);

            for each (var wheelBody:b2Body in wheelArray)
            {
                graphics.drawCircle(
                    wheelBody.GetPosition().x * scaleFactor,
                    wheelBody.GetPosition().y * scaleFactor,
                    (wheelBody.GetFixtureList().GetShape() as b2CircleShape).GetRadius() * scaleFactor
                );

            }
        }


        private function createWheel(radius:Number, startX:Number, startY:Number, velocityX:Number, velocityY:Number):void
        {
            var wheelBodyDef:b2BodyDef = new b2BodyDef();
            wheelBodyDef.type = b2Body.b2_dynamicBody;
            wheelBodyDef.position.Set(startX / scaleFactor, startY / scaleFactor);
            var wheelBody:b2Body = world.CreateBody(wheelBodyDef);
            var circleShape:b2CircleShape = new b2CircleShape(radius);
            var wheelFixtureDef:b2FixtureDef = new b2FixtureDef();
            wheelFixtureDef.shape = circleShape;
            wheelFixtureDef.restitution = (Math.random() * 0.5) + 0.5;
            wheelFixtureDef.friction = (Math.random() * 1.0);
            wheelFixtureDef.density = Math.random() * 20;
            var wheelFixture:b2Fixture = wheelBody.CreateFixture(wheelFixtureDef);

            var startingVelocity:b2Vec2 = new b2Vec2(velocityX, velocityY);
            wheelBody.SetLinearVelocity(startingVelocity);

            wheelArray.push(wheelBody);
        }
    }
}

它的工作，但在检测阶段的边界问题。

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目标：我想设置边界，因此任何帮助…

Box2D没有“边界”系统，因此，您必须

• 创建实体/实体并将其放置在需要边界的位置
• 另一件你必须注意的事情是隧道挖掘。你必须正确处理它，这样就不会有物体通过边界。您可以做的一件事是将快速移动对象的

  bullet

  -标志设置为true

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不清楚是要防止物体超出边界，还是只想检测它们是否超出边界。我要防止物体超出边界您可以设置大型静态装置作为墙。

var main:Main = new Main();

this.addElement(main);