private void initFilter(Filter filter, ViewPort vp) {
        filter.setProcessor(this);
        if (filter.isRequiresDepthTexture()) {
            if (!computeDepth && renderFrameBuffer != null) {
                depthTexture = new Texture2D(width, height, depthFormat);
                renderFrameBuffer.setDepthTarget(FrameBufferTarget.newTarget(depthTexture));
            }
            computeDepth = true;
            filter.init(assetManager, renderManager, vp, width, height);
            filter.setDepthTexture(depthTexture);
        } else {
            filter.init(assetManager, renderManager, vp, width, height);
        }
    }
init the given filter
@param filter
@param vp
jme3-core/src/main/java/com/jme3/post/FilterPostProcessor.java