protected void displayShadowMap(Renderer r) {
        Camera cam = viewPort.getCamera();
        renderManager.setCamera(cam, true);
        int h = cam.getHeight();
        for (int i = 0; i < dispPic.length; i++) {
            dispPic[i].setPosition((128 * i) + (150 + 64 * (i + 1)), h / 20f);
            dispPic[i].setWidth(128);
            dispPic[i].setHeight(128);
            dispPic[i].updateGeometricState();
            renderManager.renderGeometry(dispPic[i]);
        }
        renderManager.setCamera(cam, false);
    }
For debugging purposes, display depth shadow maps.
jme3-vr/src/main/java/com/jme3/shadow/AbstractShadowRendererVR.java