public void runControlRender(RenderManager rm, ViewPort vp) {
        if (controls.isEmpty()) {
            return;
        }

        for (Control c : controls.getArray()) {
            c.render(rm, vp);
        }
    }
Called when the Spatial is about to be rendered, to notify
controls attached to this Spatial using the Control.render() method.

@param rm The RenderManager rendering the Spatial.
@param vp The ViewPort to which the Spatial is being rendered to.

@see Spatial#addControl(com.jme3.scene.control.Control)
@see Spatial#getControl(java.lang.Class)
jme3-core/src/main/java/com/jme3/scene/Spatial.java