@Override
    public void postFrame(FrameBuffer out) {

        FrameBuffer sceneBuffer = renderFrameBuffer;
        if (renderFrameBufferMS != null && !renderer.getCaps().contains(Caps.OpenGL32)) {
            renderer.copyFrameBuffer(renderFrameBufferMS, renderFrameBuffer, true, true);
        } else if (renderFrameBufferMS != null) {
            sceneBuffer = renderFrameBufferMS;
        }
        renderFilterChain(renderer, sceneBuffer);
        renderer.setFrameBuffer(outputBuffer);

        //viewport can be null if no filters are enabled
        if (viewPort != null) {
            renderManager.setCamera(viewPort.getCamera(), false);
        }
    }
iterate through the filter list and renders filters
@param r
@param sceneFb
jme3-core/src/main/java/com/jme3/post/FilterPostProcessor.java