0, side:THREE.DoubleSide, opacity:0.3, transparent:true  } );
                var planeLeft = new THREE.Mesh( planeGeo, matLeft );
                planeLeft.name = "left";
                planeLeft.position.x = -10;
                planeLeft.position.y = 0;
                planeLeft.rotateY( Math.PI / 2 );
                walls.add(planeLeft);

                gfxScene.add(walls);
            }

            function checkWallCollision ( mesh ) {

                if ( mesh.position.x > mesh.limi