public void setShadowZExtend(float zFar) {
        this.zFarOverride = zFar;
        if(zFarOverride == 0){
            fadeInfo = null;
            frustumCam = null;
        }else{
            if (fadeInfo != null) {
                fadeInfo.set(zFarOverride - fadeLength, 1f / fadeLength);
            }
            if(frustumCam == null && viewPort != null){
                initFrustumCam();
            }
        }
    }
Set the distance from the eye where the shadows will be rendered default
value is dynamically computed to the shadow casters/receivers union bound
zFar, capped to view frustum far value.

@param zFar the zFar values that override the computed one
jme3-vr/src/main/java/com/jme3/shadow/AbstractShadowRendererVR.java