private void createVehicle() {
        suspensionNode.detachAllChildren();
        for (int i = 0; i < body.getNumWheels(); i++) {
            VehicleWheel physicsVehicleWheel = body.getWheel(i);
            Vector3f location = physicsVehicleWheel.getLocation().clone();
            Vector3f direction = physicsVehicleWheel.getDirection().clone();
            Vector3f axle = physicsVehicleWheel.getAxle().clone();
            float restLength = physicsVehicleWheel.getRestLength();
            float radius = physicsVehicleWheel.getRadius();

            Arrow locArrow = new Arrow(location);
            Arrow axleArrow = new Arrow(axle.normalizeLocal().multLocal(0.3f));
            Arrow wheelArrow = new Arrow(direction.normalizeLocal().multLocal(radius));
            Arrow dirArrow = new Arrow(direction.normalizeLocal().multLocal(restLength));
            Geometry locGeom = new Geometry("WheelLocationDebugShape" + i, locArrow);
            Geometry dirGeom = new Geometry("WheelDirectionDebugShape" + i, dirArrow);
            Geometry axleGeom = new Geometry("WheelAxleDebugShape" + i, axleArrow);
            Geometry wheelGeom = new Geometry("WheelRadiusDebugShape" + i, wheelArrow);
            dirGeom.setLocalTranslation(location);
            axleGeom.setLocalTranslation(location.add(direction));
            wheelGeom.setLocalTranslation(location.add(direction));
            locGeom.setMaterial(debugAppState.DEBUG_MAGENTA);
            dirGeom.setMaterial(debugAppState.DEBUG_MAGENTA);
            axleGeom.setMaterial(debugAppState.DEBUG_MAGENTA);
            wheelGeom.setMaterial(debugAppState.DEBUG_MAGENTA);
            suspensionNode.attachChild(locGeom);
            suspensionNode.attachChild(dirGeom);
            suspensionNode.attachChild(axleGeom);
            suspensionNode.attachChild(wheelGeom);
        }
    }
Alter which spatial is controlled. Invoked when the control is added to
or removed from a spatial. Should be invoked only by a subclass or from
Spatial. Do not invoke directly from user code.

@param spatial the spatial to control (or null)
jme3-jbullet/src/main/java/com/jme3/bullet/debug/BulletVehicleDebugControl.java