 ( mesh.position.z > mesh.limit ) {
                    mesh.velocity.z = -Math.abs(mesh.velocity.z);
                } else if (mesh.position.z < -mesh.limit ) {
                    mesh.velocity.z = Math.abs(mesh.velocity.z);
                }

                if (mesh.position.x > WALL_LIMIT || mesh.position.x < -WALL_LIMIT || mesh.position.y > WALL_LIMIT ||
                    mesh.position.y < -WALL_LIMIT || mesh.position.z > WALL_LIMIT || mesh.position.z < -WALL_LIMIT)  {
                    c