public RenderState getPreShadowForcedRenderState() {
        return shadowRenderer.getPreShadowForcedRenderState();
    }
Get the pre-shadows pass render state.
use it to adjust the RenderState parameters of the pre shadow pass.
Note that this will be overridden if the preShadow technique in the material has a ForcedRenderState
@return the pre shadow render state.
jme3-vr/src/main/java/com/jme3/shadow/AbstractShadowFilterVR.java