public static float computeZFar(GeometryList occ, GeometryList recv, Camera cam) {
        Matrix4f mat = cam.getViewMatrix();
        BoundingBox bbOcc = ShadowUtil.computeUnionBound(occ, mat);
        BoundingBox bbRecv = ShadowUtil.computeUnionBound(recv, mat);

        return min(max(bbOcc.getZExtent() - bbOcc.getCenter().z, bbRecv.getZExtent() - bbRecv.getCenter().z), cam.getFrustumFar());
    }
Compute the Zfar in the model view to adjust the Zfar distance for the splits calculation

@param occ a list of occluders
@param recv a list of receivers
@param cam the Camera (not null, unaffected)
@return the Z-far distance
jme3-core/src/main/java/com/jme3/shadow/PssmShadowUtil.java