滑轮关节(b2PulleyJoint)

最新推荐文章于 2017-09-11 08:48:24 发布

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最新推荐文章于 2017-09-11 08:48:24 发布

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/kingBook/p/5062539.html

本文介绍如何使用Box2D物理引擎创建带有滑轮关节(PulleyJoint)的物理模拟场景，包括创建刚体、圆形物体及设置滑轮关节参数等关键步骤。

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 1 package{
 2     import Box2D.Collision.b2AABB;
 3     import Box2D.Collision.b2RayCastInput;
 4     import Box2D.Collision.b2RayCastOutput;
 5     import Box2D.Collision.Shapes.b2CircleShape;
 6     import Box2D.Collision.Shapes.b2PolygonShape;
 7     import Box2D.Collision.Shapes.b2Shape;
 8     import Box2D.Common.Math.b2Vec2;
 9     import Box2D.Dynamics.b2Body;
10     import Box2D.Dynamics.b2BodyDef;
11     import Box2D.Dynamics.b2Fixture;
12     import Box2D.Dynamics.b2FixtureDef;
13     import Box2D.Dynamics.b2World;
14     import flash.display.Sprite;
15     import flash.utils.getTimer;
16     import Box2D.Dynamics.Joints.b2PulleyJoint;
17     import Box2D.Dynamics.Joints.b2PulleyJointDef;
18 
19     /**
20     * 
21     */
22     public class Main extends BaseMain{
23         
24         
25         public function Main(){
26             super(new b2Vec2(0,10));
27         }
28         
29         override protected function init():void{
30             var bodyA:b2Body=this.createBox(50,50,100,400);
31             var bodyB:b2Body=this.createCircle(25,700,400);
32             
33             var jointDef:b2PulleyJointDef=new b2PulleyJointDef();
34             
35             //悬挂的两个点
36             var gaA:b2Vec2=new b2Vec2(100/_pixelToMeter,100/_pixelToMeter);
37             var gaB:b2Vec2=new b2Vec2(700/_pixelToMeter,100/_pixelToMeter);
38             
39             var anchorA:b2Vec2=bodyA.GetWorldCenter();
40             var anchorB:b2Vec2=bodyB.GetWorldCenter();
41             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。
42             jointDef.Initialize(bodyA,bodyB,gaA,gaB,anchorA,anchorB,r);
43             var joint:b2PulleyJoint=_world.CreateJoint(jointDef) as b2PulleyJoint;
44         }
45         
46         override protected function stepBefore():void{ 
47             
48         }
49         
50         
51     };
52 }