Question

我有以下Rope Joint代码（Box2dweb）。问题是当我在浏览器中运行代码时没有任何反应。只是一块空白的画布。当我删除定义关节的线条（//关节后面的八条线）时，它会运行，我可以看到一个静态框和两个动态框落在地面上。请帮忙。

<html>
   <head>
      <title>Box2dWeb</title>
   </head>
   <body>
      <canvas id="canvas" width="600" height="400" style="background-color:#333333;" ></canvas>
   </body>
   <script type="text/javascript" src="Box2dWeb-2.1.a.3.js"></script>
   <script type="text/javascript">
        var    b2Vec2 = Box2D.Common.Math.b2Vec2
        ,      b2BodyDef = Box2D.Dynamics.b2BodyDef
        ,      b2Body = Box2D.Dynamics.b2Body
        ,      b2FixtureDef = Box2D.Dynamics.b2FixtureDef
        ,      b2World = Box2D.Dynamics.b2World
        ,      b2PolygonShape = Box2D.Collision.Shapes.b2PolygonShape
        ,      b2CircleShape = Box2D.Collision.Shapes.b2CircleShape
        ,      b2RevoluteJointDef = Box2D.Dynamics.Joints.b2RevoluteJointDef
        ,      b2DistanceJointDef = Box2D.Dynamics.Joints.b2DistanceJointDef
        ,      b2RopeJointDef = Box2D.Dynamics.Joints.b2RopeJointDef
        ,      b2MouseJointDef =  Box2D.Dynamics.Joints.b2MouseJointDef
        ,      b2DebugDraw = Box2D.Dynamics.b2DebugDraw
        ,      b2Fixture = Box2D.Dynamics.b2Fixture
        ,      b2AABB = Box2D.Collision.b2AABB
        ,      b2Color = Box2D.Common.b2Color;

        var world = new b2World(new b2Vec2(0,10), true);

        //box1

        var bodyDef = new b2BodyDef;
        bodyDef.type = b2Body.b2_dynamicBody;
        bodyDef.position.Set(8,4);

        var fixDef = new b2FixtureDef;
        fixDef.density = 10.0;
        fixDef.friction = 0.5;
        fixDef.restitution = .5;

        fixDef.shape = new b2PolygonShape;
        fixDef.shape.SetAsBox(.3,.3);

        var box1 = world.CreateBody(bodyDef);
        box1.CreateFixture(fixDef);

        //box2

            var bodyDef2 = new b2BodyDef;
        bodyDef2.type = b2Body.b2_dynamicBody;
        bodyDef2.position.Set(14,8);

        var fixDef2 = new b2FixtureDef;
        fixDef2.density = 10.0;
        fixDef2.friction = 0.5;
        fixDef2.restitution = .2; 
        fixDef2.shape = new b2PolygonShape;
        fixDef2.shape.SetAsBox(.3,.3);

            var box2 = world.CreateBody(bodyDef2);
        box2.CreateFixture(fixDef2);

        //box3 - static

            var bodyDef3 = new b2BodyDef;
        bodyDef3.type = b2Body.b2_staticBody;
        bodyDef3.position.Set(11,8);

        var fixDef3 = new b2FixtureDef;
        fixDef3.friction = 0.5;
        fixDef3.restitution = .2; 
        fixDef3.shape = new b2PolygonShape;
        fixDef3.shape.SetAsBox(.3,.3);

            var box3 = world.CreateBody(bodyDef3);
        box3.CreateFixture(fixDef3);

         //create a ground

             var holderDef = new b2BodyDef;
             holderDef.type = b2Body.b2_staticBody;
             holderDef.position.Set(10, 14);

         var fd = new b2FixtureDef;
         fd.shape = new b2PolygonShape;
         fd.shape.SetAsBox(10,1);

             var ground = world.CreateBody(holderDef);
         ground.CreateFixture(fd);

         //  joints

        var ropeJointDef = new b2RopeJointDef();
        ropeJointDef.bodyA = box1;
        ropeJointDef.bodyB = box2;
        ropeJointDef.localAnchorA = new b2Vec2(0,0);
        ropeJointDef.localAnchorB = new b2Vec2(0,0);
        ropeJointDef.maxLength = 6;
        ropeJointDef.collideConnected = true;
        world.CreateJoint(ropeJointDef);

        var debugDraw = new b2DebugDraw();
        debugDraw.SetSprite ( document.getElementById ("canvas").getContext ("2d"));
        debugDraw.SetDrawScale(30);     //define scale
        debugDraw.SetFillAlpha(0.3);    //define transparency
        debugDraw.SetLineThickness(1.0);
        debugDraw.SetFlags(b2DebugDraw.e_shapeBit | b2DebugDraw.e_jointBit);
        world.SetDebugDraw(debugDraw);

        window.setInterval(update,1000/60);

        function update() {
            world.Step(1 / 60, 10, 10);
            world.DrawDebugData();
            world.ClearForces();
        };

   </script>


</html>

Answer 1

我在Box2DWeb中添加了对Rope Joints的支持。

https://github.com/aaronfarr/box2Dweb

希望你觉得它很有用

Answer 2

绳索接头是Box2D的一个相对较新的附加物。我猜你正在使用的javascript端口没有它。至少，我在这里找不到它：http://code.google.com/p/box2dweb/source/browse/trunk/Box2D.js

Box2dweb - 绳索联合不起作用

2 个答案: