WIP: Volume Scattering Probability Guiding

CMakeLists.txt

@@ -52,6 +52,7 @@ option(OPENPGL_BUILD_CHECK_TOOL "Build check tool application." OFF)
 try_compile(COMPILER_SUPPORTS_ARM_NEON "${CMAKE_BINARY_DIR}" "${PROJECT_SOURCE_DIR}/cmake/check_arm_neon.cpp")
 
 OPTION(OPENPGL_EF_RADIANCE_CACHES "Enables experimental feature (ir)radiance caches." OFF)
+OPTION(OPENPGL_EF_VSP_GUIDING "Enables experimental feature volume scatter probability guiding." OFF)
 OPTION(OPENPGL_EF_IMAGE_SPACE_GUIDING_BUFFER "Enables experimental feature ImageSpaceGuidignBuffer." OFF)
 
 OPTION(OPENPGL_DIRECTION_COMPRESSION "Using 32-Bit compression to represent directions." OFF)

openpgl/CMakeLists.txt

@@ -46,6 +46,11 @@ if(OPENPGL_EF_RADIANCE_CACHES)
 target_compile_definitions(${PROJECT_NAME} PRIVATE OPENPGL_RADIANCE_CACHES)
 endif()
 
+if(OPENPGL_EF_VSP_GUIDING)
+target_compile_definitions(${PROJECT_NAME} PRIVATE OPENPGL_VSP_GUIDING)
+endif()
+
+
 if(OPENPGL_EF_IMAGE_SPACE_GUIDING_BUFFER)
 target_compile_definitions(${PROJECT_NAME} PRIVATE OPENPGL_IMAGE_SPACE_GUIDING_BUFFER)
 endif()
@@ -235,6 +240,11 @@ if(OPENPGL_EF_RADIANCE_CACHES)
   set(OPENPGL_RADIANCE_CACHES ON)
 endif()
 
+if(OPENPGL_EF_VSP_GUIDING)
+  set(OPENPGL_VSP_GUIDING ON)
+endif()
+
+
 if(OPENPGL_EF_IMAGE_SPACE_GUIDING_BUFFER)
   set(OPENPGL_IMAGE_SPACE_GUIDING_BUFFER ON)
 endif()

openpgl/api/api.cpp

@@ -602,6 +602,14 @@ extern "C" OPENPGL_DLLEXPORT uint32_t pglSurfaceSamplingDistributionGetId(PGLSur
     return gSurfaceSamplingDistribution->getId();
 }
 
+#ifdef OPENPGL_VSP_GUIDING
+extern "C" OPENPGL_DLLEXPORT float pglSurfaceSamplingDistributionVolumeScatterProbability(PGLSurfaceSamplingDistribution surfaceSamplingDistribution, pgl_vec3f direction)
+{
+    ISurfaceSamplingDistribution *gSurfaceSamplingDistribution = (ISurfaceSamplingDistribution *)surfaceSamplingDistribution;
+    return gSurfaceSamplingDistribution->volumeScatterProbability(openpgl::Vector3(direction.x, direction.y, direction.z));
+}
+#endif
+
 extern "C" OPENPGL_DLLEXPORT bool pglSurfaceSamplingDistributionValidate(PGLSurfaceSamplingDistribution surfaceSamplingDistribution)
 {
     ISurfaceSamplingDistribution *gSurfaceSamplingDistribution = (ISurfaceSamplingDistribution *)surfaceSamplingDistribution;
@@ -700,6 +708,14 @@ extern "C" OPENPGL_DLLEXPORT uint32_t pglVolumeSamplingDistributionGetId(PGLVolu
     return gVolumeSamplingDistribution->getId();
 }
 
+#ifdef OPENPGL_VSP_GUIDING
+extern "C" OPENPGL_DLLEXPORT float pglVolumeSamplingDistributionVolumeScatterProbability(PGLVolumeSamplingDistribution volumeSamplingDistribution, pgl_vec3f direction)
+{
+    IVolumeSamplingDistribution *gVolumeSamplingDistribution = (IVolumeSamplingDistribution *)volumeSamplingDistribution;
+    return gVolumeSamplingDistribution->volumeScatterProbability(openpgl::Vector3(direction.x, direction.y, direction.z));
+}
+#endif
+
 extern "C" OPENPGL_DLLEXPORT bool pglVolumeSamplingDistributionValidate(PGLVolumeSamplingDistribution volumeSamplingDistribution)
 {
     IVolumeSamplingDistribution *gVolumeSamplingDistribution = (IVolumeSamplingDistribution *)volumeSamplingDistribution;
@@ -867,9 +883,9 @@ extern "C" OPENPGL_DLLEXPORT void pglReleaseString(PGLString str)
 // ImageSpaceGuidingBuffer  ///////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////
 
-extern "C" OPENPGL_DLLEXPORT PGLImageSpaceGuidingBuffer pglFieldNewImageSpaceGuidingBuffer(const pgl_point2i resolution)
+extern "C" OPENPGL_DLLEXPORT PGLImageSpaceGuidingBuffer pglFieldNewImageSpaceGuidingBuffer(const PGLImageSpaceGuidingBufferConfig cfg)
 {
-    return (PGLImageSpaceGuidingBuffer) new openpgl::ImageSpaceGuidingBuffer(resolution, false);
+    return (PGLImageSpaceGuidingBuffer) new openpgl::ImageSpaceGuidingBuffer(cfg);
 }
 
 extern "C" OPENPGL_DLLEXPORT PGLImageSpaceGuidingBuffer pglFieldNewImageSpaceGuidingBufferFromFile(const char *fileName)
@@ -901,12 +917,20 @@ extern "C" OPENPGL_DLLEXPORT void pglImageSpaceGuidingBufferStore(PGLImageSpaceG
     gImageSpaceGuidingBuffer->store(fileName);
 }
 
-extern "C" OPENPGL_DLLEXPORT pgl_vec3f pglImageSpaceGuidingBufferGetPixelContributionEstimate(PGLImageSpaceGuidingBuffer imageSpaceGuidingBuffer, const pgl_point2i pixel)
+extern "C" OPENPGL_DLLEXPORT pgl_vec3f pglImageSpaceGuidingBufferGetContributionEstimate(PGLImageSpaceGuidingBuffer imageSpaceGuidingBuffer, const pgl_point2i pixel)
 {
     auto *gImageSpaceGuidingBuffer = (openpgl::ImageSpaceGuidingBuffer *)imageSpaceGuidingBuffer;
     return gImageSpaceGuidingBuffer->getContributionEstimate(pixel);
 }
 
+#if defined(OPENPGL_VSP_GUIDING)
+extern "C" OPENPGL_DLLEXPORT float pglImageSpaceGuidingBufferGetVolumeScatterProbabilityEstimate(PGLImageSpaceGuidingBuffer imageSpaceGuidingBuffer, const pgl_point2i pixel)
+{
+    auto *gImageSpaceGuidingBuffer = (openpgl::ImageSpaceGuidingBuffer *)imageSpaceGuidingBuffer;
+    return gImageSpaceGuidingBuffer->getVolumeScatterProbabilityEstimate(pixel);
+}
+#endif
+
 extern "C" OPENPGL_DLLEXPORT bool pglImageSpaceGuidingBufferIsReady(PGLImageSpaceGuidingBuffer imageSpaceGuidingBuffer)
 {
     auto *gImageSpaceGuidingBuffer = (openpgl::ImageSpaceGuidingBuffer *)imageSpaceGuidingBuffer;

openpgl/data/PathSegmentDataStorage.h

@@ -260,6 +260,11 @@ struct PathSegmentDataStorage
                     flags |= SampleData::EInsideVolume;
                 }
 
+                if (m_segmentStorage[i + 1].volumeScatter)
+                {
+                    flags |= SampleData::ENextEventVolume;
+                }
+
                 bool directLightSample = false;
 #ifdef OPENPGL_RADIANCE_CACHES
                 float misWeight = 1.f;
@@ -398,7 +403,7 @@ struct PathSegmentDataStorage
                     pglDirection = {dirOut[0], dirOut[1], dirOut[2]};
                     isd.directionOut = pglDirection;
 #endif
-                    isd.volume = insideVolume;
+                    isd.flags = flags;
 #if defined(OPENPGL_PATHSEGMENT_STORAGE_USE_ARRAY)
                     if (m_zero_value_sample_idx + 1 <= m_max_zero_value_sample_size)
                     {

openpgl/data/Range.h

@@ -12,7 +12,7 @@ struct Range
     size_t m_begin{0};
     size_t m_end{0};
 
-#ifdef OPENPGL_RADIANCE_CACHES
+#if defined(OPENPGL_RADIANCE_CACHES) || defined(OPENPGL_VSP_GUIDING)
     size_t m_is_begin{0};
     size_t m_is_end{0};
 #endif
@@ -25,7 +25,7 @@ struct Range
         OPENPGL_ASSERT(int(m_end) - int(m_begin) >= 0);
         return m_end - m_begin;
     }
-#ifdef OPENPGL_RADIANCE_CACHES
+#if defined(OPENPGL_RADIANCE_CACHES) || defined(OPENPGL_VSP_GUIDING)
     inline size_t sizeZeroValueSamples() const
     {
         OPENPGL_ASSERT(int(m_is_end) - int(m_is_begin) >= 0);
@@ -36,7 +36,7 @@ struct Range
     {
         m_begin = 0;
         m_end = 0;
-#ifdef OPENPGL_RADIANCE_CACHES
+#if defined(OPENPGL_RADIANCE_CACHES) || defined(OPENPGL_VSP_GUIDING)
         m_is_begin = 0;
         m_is_end = 0;
 #endif
@@ -46,7 +46,7 @@ struct Range
     {
         os.write(reinterpret_cast<const char *>(&m_begin), sizeof(m_begin));
         os.write(reinterpret_cast<const char *>(&m_end), sizeof(m_end));
-#ifdef OPENPGL_RADIANCE_CACHES
+#if defined(OPENPGL_RADIANCE_CACHES) || defined(OPENPGL_VSP_GUIDING)
         os.write(reinterpret_cast<const char *>(&m_is_begin), sizeof(m_is_begin));
         os.write(reinterpret_cast<const char *>(&m_is_end), sizeof(m_is_end));
 #endif
@@ -56,7 +56,7 @@ struct Range
     {
         is.read(reinterpret_cast<char *>(&m_begin), sizeof(m_begin));
         is.read(reinterpret_cast<char *>(&m_end), sizeof(m_end));
-#ifdef OPENPGL_RADIANCE_CACHES
+#if defined(OPENPGL_RADIANCE_CACHES) || defined(OPENPGL_VSP_GUIDING)
         is.read(reinterpret_cast<char *>(&m_is_begin), sizeof(m_is_begin));
         is.read(reinterpret_cast<char *>(&m_is_end), sizeof(m_is_end));
 #endif
@@ -66,7 +66,7 @@ struct Range
     {
         bool equal = true;
         if (m_begin != b.m_begin || m_end != b.m_end
-#ifdef OPENPGL_RADIANCE_CACHES
+#if defined(OPENPGL_RADIANCE_CACHES) || defined(OPENPGL_VSP_GUIDING)
             || m_is_begin != b.m_is_begin || m_is_end != b.m_is_end
 #endif
         )

openpgl/data/SampleData.h

@@ -22,7 +22,8 @@ typedef PGLSampleData SampleData;
 enum SampleData_Flags
 {
     EInsideVolume = 1 << 0,  // point does not represent any real scene intersection point
-    EDirectLight = 1 << 1    // if the samples represents direct light from a light source
+    EDirectLight = 1 << 1,   // if the samples represents direct light from a light source
+    ENextEventVolume = 1 << 2
 };
 
 inline bool isValid(const SampleData &dsd)
@@ -86,6 +87,11 @@ inline bool isDirectLight(const SampleData &sd)
     return (sd.flags & EDirectLight);
 }
 
+inline bool isNextEventVolume(const SampleData &sd)
+{
+    return (sd.flags & ENextEventVolume);
+}
+
 inline std::string toString(const SampleData &sd)
 {
     std::stringstream ss;
@@ -186,6 +192,16 @@ inline bool ZeroValueSampleDataLess(const PGLZeroValueSampleData &compA, const P
                     )))));
 }
 
+inline bool isInsideVolume(const PGLZeroValueSampleData &zvsd)
+{
+    return (zvsd.flags & EInsideVolume);
+}
+
+inline bool isNextEventVolume(const PGLZeroValueSampleData &zvsd)
+{
+    return (zvsd.flags & ENextEventVolume);
+}
+
 inline SampleData *LoadSampleData(const std::string fileName, size_t &numData)
 {
     std::ifstream file;

openpgl/data/SampleDataStorage.h

@@ -104,7 +104,7 @@ struct SampleDataStorage
 
     inline void addZeroValueSample(const ZeroValueSampleData &sample)
     {
-        if (sample.volume)
+        if (isInsideVolume(sample))
         {
             m_volumeContainer.zeroValueSamples.push_back(sample);
         }

openpgl/device/Device.h

@@ -99,6 +99,9 @@ struct Device : public IDevice
             typename GuidingField::Settings gFieldSettings;
             gFieldSettings.settings.decayOnSpatialSplit = 0.25f;
             gFieldSettings.settings.deterministic = args.deterministic;
+#ifdef OPENPGL_VSP_GUIDING
+            gFieldSettings.settings.varianceBasedVSP = args.varianceBasedVSP;
+#endif
             gFieldSettings.debugSettings.fitRegions = args.debugArguments.fitRegions;
 
             PGLKDTreeArguments *spatialSturctureArguments = (PGLKDTreeArguments *)args.spatialSturctureArguments;
@@ -148,6 +151,9 @@ struct Device : public IDevice
             typename GuidingField::Settings gFieldSettings;
             gFieldSettings.settings.decayOnSpatialSplit = 0.25f;
             gFieldSettings.settings.deterministic = args.deterministic;
+#ifdef OPENPGL_VSP_GUIDING
+            gFieldSettings.settings.varianceBasedVSP = args.varianceBasedVSP;
+#endif
             gFieldSettings.debugSettings.fitRegions = args.debugArguments.fitRegions;
 
             PGLKDTreeArguments *spatialSturctureArguments = (PGLKDTreeArguments *)args.spatialSturctureArguments;
@@ -197,6 +203,9 @@ struct Device : public IDevice
             typename GuidingField::Settings gFieldSettings;
             gFieldSettings.settings.decayOnSpatialSplit = 0.25f;
             gFieldSettings.settings.deterministic = args.deterministic;
+#ifdef OPENPGL_VSP_GUIDING
+            gFieldSettings.settings.varianceBasedVSP = args.varianceBasedVSP;
+#endif
             gFieldSettings.debugSettings.fitRegions = args.debugArguments.fitRegions;
 
             PGLKDTreeArguments *spatialSturctureArguments = (PGLKDTreeArguments *)args.spatialSturctureArguments;

openpgl/directional/ISurfaceSamplingDistribution.h

@@ -57,6 +57,10 @@ struct ISurfaceSamplingDistribution
 
     virtual const IRegion *getRegion() const = 0;
 
+#ifdef OPENPGL_VSP_GUIDING
+    virtual float volumeScatterProbability(Vector3 dir) const = 0;
+#endif
+
    protected:
     // const IRegion* m_region {nullptr};
     uint32_t m_id{0};

openpgl/directional/IVolumeSamplingDistribution.h

@@ -59,6 +59,10 @@ struct IVolumeSamplingDistribution
 
     virtual const IRegion *getRegion() const = 0;
 
+#ifdef OPENPGL_VSP_GUIDING
+    virtual float volumeScatterProbability(Vector3 dir) const = 0;
+#endif
+
    protected:
     // const IRegion* m_region {nullptr};
     uint32_t m_id{0};

openpgl/directional/dqt/DQTFactory.h

@@ -154,6 +154,11 @@ class DirectionalQuadtreeFactory
             is.read(reinterpret_cast<char *>(nodes.data()), size * sizeof(nodes[0]));
         };
 
+        float getNumSamples() const
+        {
+            return numSamples;
+        };
+
         // TODO: Needs to be implmented
         bool operator==(const Statistics &b) const
         {
@@ -175,6 +180,10 @@ class DirectionalQuadtreeFactory
                                const SampleStatistics &sampleStatistics) const
     {}
 
+    void updateVolumeScatterProbability(Distribution &dist, Statistics &stats, const SampleData *samples, const size_t numSamples, const ZeroValueSampleData *zeroValueSamples,
+                                        const size_t numZeroValueSamples, const bool varianceBased) const
+    {}
+
     void fit(Distribution &dist, Statistics &stats, const SampleData *samples, const size_t numSamples, const Configuration &cfg, FittingStatistics &fitStats)
     {
         for (uint32_t i = 0; i < 5; i++)

openpgl/directional/dqt/DQTSurfaceSamplingDistribution.h

@@ -87,6 +87,13 @@ struct DQTSurfaceSamplingDistribution : public ISurfaceSamplingDistribution
         m_region = region;
     }
 
+#ifdef OPENPGL_VSP_GUIDING
+    float volumeScatterProbability(Vector3 dir) const override
+    {
+        return 0.f;
+    }
+#endif
+
    private:
     TDirectionalQuadtree distribution;
     const IRegion *m_region{nullptr};

openpgl/directional/dqt/DQTVolumeSamplingDistribution.h

@@ -93,6 +93,13 @@ struct DQTVolumeSamplingDistribution : public IVolumeSamplingDistribution
         m_region = region;
     }
 
+#ifdef OPENPGL_VSP_GUIDING
+    float volumeScatterProbability(Vector3 dir) const override
+    {
+        return 0.f;
+    }
+#endif
+
    private:
     TDirectionalQuadtree distribution;
     const IRegion *m_region{nullptr};

openpgl/directional/vmm/AdaptiveSplitandMergeFactory.h

@@ -95,6 +95,10 @@ struct AdaptiveSplitAndMergeFactory
             return sufficientStatistics.getNumComponents();
         }
 
+        inline float getNumSamples() const
+        {
+            return sufficientStatistics.getNumSamples();
+        };
         std::string toString() const;
 
         bool operator==(const Statistics &b) const;
@@ -122,6 +126,9 @@ struct AdaptiveSplitAndMergeFactory
 
     void updateFluenceEstimate(VMM &vmm, const SampleData *samples, const size_t numSamples, const size_t numZeroValueSamples, const SampleStatistics &sampleStatistics) const;
 
+    void updateVolumeScatterProbability(VMM &vmm, Statistics &stats, const SampleData *samples, const size_t numSamples, const ZeroValueSampleData *zeroValueSamples,
+                                        const size_t numZeroValueSamples, const bool varianceBased) const;
+
     std::string toString() const
     {
         std::ostringstream oss;
@@ -463,4 +470,13 @@ void AdaptiveSplitAndMergeFactory<TVMMDistribution>::updateFluenceEstimate(VMM &
     factory.updateFluenceEstimate(vmm, samples, numSamples, numZeroValueSamples, sampleStatistics);
 }
 
+template <class TVMMDistribution>
+void AdaptiveSplitAndMergeFactory<TVMMDistribution>::updateVolumeScatterProbability(VMM &vmm, Statistics &stats, const SampleData *samples, const size_t numSamples,
+                                                                                    const ZeroValueSampleData *zeroValueSamples, const size_t numZeroValueSamples,
+                                                                                    const bool varianceBased) const
+{
+    WeightedEMFactory factory = WeightedEMFactory();
+    factory.updateVolumeScatterProbability(vmm, stats.sufficientStatistics, samples, numSamples, zeroValueSamples, numZeroValueSamples, varianceBased);
+}
+
 }  // namespace openpgl