     switch (event.keyCode) {
                case 37:
                    vr = -3;
                    break; //left
                case 39:
                    vr = 3;
                    break; //right
                case 38:
                    thrust = 0.08;
                    ship.showFlame = true;
                    break; //up
                }
            }, false);
            window.addEventListener("keyup", function (event) {
                vr=0;
                thrust=0;
                sh