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#ifndef OcclusionCullRenderer_INCLUDE_ONCE
#define OcclusionCullRenderer_INCLUDE_ONCE

#include <vlGraphics/Renderer.hpp>

namespace vl
{
  //------------------------------------------------------------------------------
  // OcclusionCullRenderer
  //------------------------------------------------------------------------------
  /** Wraps a Renderer performing occlusion culling acceleration.
    * For more information see \ref pagGuideOcclusionCulling */
  class VLGRAPHICS_EXPORT OcclusionCullRenderer: public Renderer
  {
    VL_INSTRUMENT_CLASS(vl::OcclusionCullRenderer, Renderer)

  public:
    /** Constructor. */
    OcclusionCullRenderer();

    /** Renders using the wrapped renderer but also performing occlusion culling. */
    virtual const RenderQueue* render(const RenderQueue* in_render_queue, Camera* camera, real frame_clock);

    /** The renderer to be wrapped by this occlusion culling renderer */
    void setWrappedRenderer(Renderer* renderer);

    /** The renderer to be wrapped by this occlusion culling renderer */
    const Renderer* wrappedRenderer() const { return mWrappedRenderer.get(); }

    /** The renderer to we wrapped by this occlusion culling renderer */
    Renderer* wrappedRenderer() { return mWrappedRenderer.get(); }

    /** The number of pixels visible for an actor to be considered occluded (default = 0) */
    void setOcclusionThreshold(int threshold) { mOcclusionThreshold = threshold; }

    /** The number of pixels visible for an actor to be considered occluded (default = 0) */
    int occlusionThreshold() const { return mOcclusionThreshold; }

    /** Returns the wrapped Renderer's Framebuffer */
    const Framebuffer* framebuffer() const;

    /** Returns the wrapped Renderer's Framebuffer */
    Framebuffer* framebuffer();

    /** Returns the total number or objects candidate for rendering before occlusion culling. */
    int statsTotalObjects() const { return mStatsTotalObjects; }

    /** Returns the number or objects not rendered due to the occlusion culling. */
    int statsOccludedObjects() const { return mStatsOccludedObjects; }

    /** The Shader used to render the bounding boxes during the occlusion culling query.
      * For example if you have problems with the zbuffer percision you can access the Shader to modify
      * the polygon offset settings. */
    Shader* occlusionShader() { return mOcclusionShader.get(); }

    /** The Shader used to render the bounding boxes during the occlusion culling query.
      * For example if you have problems with the zbuffer percision you can access the Shader to modify
      * the polygon offset settings. */
    const Shader* occlusionShader() const { return mOcclusionShader.get(); }

    /** The Shader used to render the bounding boxes during the occlusion culling query.
      * For example if you have problems with the zbuffer percision you can access the Shader to modify
      * the polygon offset settings. */
    void setOcclusionShader(Shader* occ_sh) { mOcclusionShader = occ_sh; }

  protected:
    /** Retrieves the occlusion culling query results from the previous rendering frame. */
    void render_pass1(const RenderQueue* in_render_queue);

    /** Performs a new set of occlusion culling queries to be tested the next frame. */
    void render_pass2(const RenderQueue* in_render_queue, Camera* camera);

  protected:
    vl::ref<Renderer> mWrappedRenderer;
    ref<Shader> mOcclusionShader;
    ref<RenderQueue> mCulledRenderQueue;
    int mOcclusionThreshold;
    Renderer* mPrevWrapRenderer;
    int mStatsTotalObjects;
    int mStatsOccludedObjects;
  };
  //------------------------------------------------------------------------------
}

#endif