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 # Copyright (c) 2015-21, NVIDIA CORPORATION. All rights reserved.
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 # are met:
 #  * Redistributions of source code must retain the above copyright
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 #  * Redistributions in binary form must reproduce the above copyright
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 #    documentation and/or other materials provided with the distribution.
 #  * Neither the name of NVIDIA CORPORATION nor the names of its
 #    contributors may be used to endorse or promote products derived
 #    from this software without specific prior written permission.
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 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS "AS IS" AND ANY
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#pragma once
#include "Falcor.h"
#include "Utils/Sampling/SampleGenerator.h"
#include "Utils/Sampling/AliasTable.h"
#include "Rendering/Lights/LightBVHSampler.h"
#include "Rendering/Lights/EnvMapSampler.h"
#include "Types.slang"
#include "AccelerationStructureBuilder.h"

using namespace Falcor;

class ProgressivePhotonMapping : public RenderPass
{
public:
    using SharedPtr = std::shared_ptr<ProgressivePhotonMapping>;

    static const Info kInfo;

    static SharedPtr create(RenderContext* pRenderContext = nullptr, const Dictionary& dict = {});

    virtual Dictionary getScriptingDictionary() override;
    virtual RenderPassReflection reflect(const CompileData& compileData) override;
    virtual void compile(RenderContext* pRenderContext, const CompileData& compileData) override {}
    virtual void execute(RenderContext* pRenderContext, const RenderData& renderData) override;
    virtual void renderUI(Gui::Widgets& widget) override;
    virtual void setScene(RenderContext* pRenderContext, const Scene::SharedPtr& pScene) override;

    virtual bool onMouseEvent(const MouseEvent& mouseEvent) override { return false; }
    virtual bool onKeyEvent(const KeyboardEvent& keyEvent) override { return false; }

    void beginFrame(RenderContext* pRenderContext, const RenderData& renderData);
    void recompile();
    bool prepareLighting(RenderContext* pRenderContext);
    void generateVisiblePoints(RenderContext* pRenderContext, const RenderData& renderData);
    void generatePhotons(RenderContext* pRenderContext, const RenderData& renderData);
    void reduceRadius(RenderContext* pRenderContext, const RenderData& renderData);
    void resolve(RenderContext* pRenderContext, const RenderData& renderData);
    void endFrame(RenderContext* pRenderContext, const RenderData& renderData);

private:
    ProgressivePhotonMapping();
    void setParamShaderData(const ShaderVar& var);

    Scene::SharedPtr mpScene;
    SampleGenerator::SharedPtr mpSampleGenerator;

    LightBVHSampler::SharedPtr mpEmissiveSampler;
    EnvMapSampler::SharedPtr mpEnvMapSampler;
    AliasTable::SharedPtr mpEmissiveTable;

    Buffer::SharedPtr mpVisiblePoints;
    Buffer::SharedPtr mpVisiblePointPhotonNumbers;
    Buffer::SharedPtr mpVisiblePointDensityContexts;
    Buffer::SharedPtr mpVisiblePointsBoundingBoxBuffer;
    AccelerationStructureBuilder::SharedPtr mpVisiblePointsAS;

    ComputePass::SharedPtr mpGenerateVisiblePointsPass;
    ComputePass::SharedPtr mpGeneratePhotonsPass;
    ComputePass::SharedPtr mpSyncPhotonNumberPass;
    ComputePass::SharedPtr mpReduceRadiusPass;
    ComputePass::SharedPtr mpResolvePass;

    Texture::SharedPtr mpShadingOutput;

    PhotonMappingParams mParams;
    uint mPhotonPassNum = 10;
    bool mRecompile = true;
};
