public void atttach(AppState appState, Application application){
        this.application = application;
        this.app         = appState;

        // Instantiate view manager
        if (vrBinding == VRConstants.SETTING_VRAPI_OPENVR_VALUE){
            viewManager = new OpenVRViewManager(this);
        } else if (vrBinding == VRConstants.SETTING_VRAPI_OCULUSVR_VALUE) {
            viewManager = new OculusViewManager(this);
        } else if (vrBinding == VRConstants.SETTING_VRAPI_OPENVR_LWJGL_VALUE) {
            viewManager = new LWJGLOpenVRViewManager(this);
        } else {
            logger.severe("Cannot instantiate view manager, unknown VRAPI type: "+vrBinding);
        }
    }
Attach the VR environment to the given app state and application.
This method should be called within the {@link AppState#stateAttached(com.jme3.app.state.AppStateManager) stateAttached(com.jme3.app.state.AppStateManager)} method
from the app state.
@param appState the app state to attach.
@param application the application to attach.
jme3-vr/src/main/java/com/jme3/app/VREnvironment.java