protected void initForcedRenderState() {
        forcedRenderState.setFaceCullMode(RenderState.FaceCullMode.Front);
        forcedRenderState.setColorWrite(false);
        forcedRenderState.setDepthWrite(true);
        forcedRenderState.setDepthTest(true);
    }
Create an abstract shadow renderer. Subclasses invoke this constructor.

@param assetManager the application asset manager
@param shadowMapSize the size of the rendered shadow maps (512,1024,2048,
etc...)
@param nbShadowMaps the number of shadow maps rendered (the more shadow
maps the more quality, the fewer fps).
jme3-vr/src/main/java/com/jme3/shadow/AbstractShadowRendererVR.java