BodyDef dymBodyDef = new BodyDef();
dymBodyDef.position = new Vec2(0 , 0 );
// dymBodyDef.position = new Vec2(worldWidth*0.5f , worldHeight*0.5f);
Body theBody = world.createBody(dymBodyDef);
EdgeChainDef myEdges = new EdgeChainDef();
//CCW so edge points inwards
myEdges.addVertex(new Vec2(l.x + offset , l.y + worldHeight - offset*2));
myEdges.addVertex(new Vec2(l.x + worldWidth - offset*2, l.y + worldHeight - offset*2));
myEdges.addVertex(new Vec2(l.x + worldWidth - offset*2, l.y + offset));
myEdges.addVertex(new Vec2(l.x + offset , l.y + offset));
myEdges.setIsLoop(true);
myEdges.friction = 2.0f;
// myEdges.density = 1.0f;
myEdges.density = 0.0f;
myEdges.isSensor = true;