Cull shadow views before drawing them

Signed-off-by: Mateusz Wasilewski <[email protected]>

Author: mateuszwasilewski

Gems/Atom/Feature/Common/Code/Source/Shadows/ProjectedShadowFeatureProcessor.cpp

@@ -28,6 +28,39 @@
 
 namespace AZ::Render
 {
+    namespace
+    {
+        AZ_CVAR(
+            bool,
+            r_cullShadowmapOutsideViewFrustum,
+            true,
+            nullptr,
+            AZ::ConsoleFunctorFlags::DontReplicate | AZ::ConsoleFunctorFlags::DontDuplicate,
+            "If set, enables filtering of shadow maps that are outside of the view frustum.");
+
+        bool IsShadowmapCullingEnabled()
+        {
+            bool cullShadowmapOutsideViewFrustum = true;
+            if (auto* console = AZ::Interface<AZ::IConsole>::Get())
+            {
+                console->GetCvarValue("r_cullShadowmapOutsideViewFrustum", cullShadowmapOutsideViewFrustum);
+            }
+            return cullShadowmapOutsideViewFrustum;
+        }
+
+        bool IsLightInsideAnyViewFrustum(AZStd::span<AZ::Frustum> viewFrustums, const AZ::Vector3& lightPosition, float attenuationRadius)
+        {
+            return std::any_of(
+                viewFrustums.begin(),
+                viewFrustums.end(),
+                [lightPosition, attenuationRadius](const AZ::Frustum& viewFrustum)
+                {
+                    return viewFrustum.IntersectSphere(lightPosition, attenuationRadius) != AZ::IntersectResult::Exterior;
+                });
+        }
+
+    } // namespace
+
     void ProjectedShadowFeatureProcessor::Reflect(ReflectContext* context)
     {
         if (auto* serializeContext = azrtti_cast<SerializeContext*>(context))
@@ -631,23 +664,41 @@ namespace AZ::Render
             }
         }
     }
-    
-    void ProjectedShadowFeatureProcessor::PrepareViews(const PrepareViewsPacket&, AZStd::vector<AZStd::pair<RPI::PipelineViewTag, RPI::ViewPtr>>& outViews)
+
+    void ProjectedShadowFeatureProcessor::PrepareViews(
+        const PrepareViewsPacket& prepareViewsPacket, AZStd::vector<AZStd::pair<RPI::PipelineViewTag, RPI::ViewPtr>>& outViews)
     {
         if (m_primaryProjectedShadowmapsPass != nullptr)
         {
             RPI::RenderPipeline* renderPipeline = m_primaryProjectedShadowmapsPass->GetRenderPipeline();
             if (renderPipeline)
             {
+                AZStd::vector<AZ::Frustum> mainViewFrustums;
+                for (const auto& [view, viewTag] : prepareViewsPacket.m_persistentViews)
+                {
+                    AZ::Frustum viewFrustum = AZ::Frustum::CreateFromMatrixColumnMajor(view->GetWorldToClipMatrix());
+                    mainViewFrustums.push_back(viewFrustum);
+                }
+                bool cullShadowmapOutsideViewFrustum = IsShadowmapCullingEnabled();
+
                 auto& shadowProperties = m_shadowProperties.GetDataVector();
                 for (ShadowProperty& shadowProperty : shadowProperties)
                 {
                     uint16_t shadowIndex = shadowProperty.m_shadowId.GetIndex();
                     const FilterParameter& filterData = m_shadowData.GetElement<FilterParamIndex>(shadowIndex);
-                    if (filterData.m_shadowmapSize == aznumeric_cast<uint32_t>(ShadowmapSize::None))
+                    bool needsRender = filterData.m_shadowmapSize != aznumeric_cast<uint32_t>(ShadowmapSize::None);
+                    if (!needsRender)
+                    {
+                        continue;
+                    }
+                    auto lightPosition = shadowProperty.m_desc.m_transform.GetTranslation();
+                    if (cullShadowmapOutsideViewFrustum &&
+                        !IsLightInsideAnyViewFrustum(mainViewFrustums, lightPosition, shadowProperty.m_desc.m_farPlaneDistance))
                     {
+                        shadowProperty.m_shadowmapPass->SetEnabled(false);
                         continue;
                     }
+                    shadowProperty.m_shadowmapPass->SetEnabled(true);
 
                     const RPI::PipelineViewTag& viewTag = shadowProperty.m_shadowmapPass->GetPipelineViewTag();
                     const RHI::DrawListMask drawListMask = renderPipeline->GetDrawListMask(viewTag);

Gems/Atom/Feature/Common/Code/Source/Shadows/ProjectedShadowFeatureProcessor.h

@@ -39,7 +39,8 @@ namespace AZ::Render
         void Activate() override;
         void Deactivate() override;
         void Simulate(const SimulatePacket& packet) override;
-        void PrepareViews(const PrepareViewsPacket&, AZStd::vector<AZStd::pair<RPI::PipelineViewTag, RPI::ViewPtr>>&) override;
+        void PrepareViews(
+            const PrepareViewsPacket& prepareViewsPacket, AZStd::vector<AZStd::pair<RPI::PipelineViewTag, RPI::ViewPtr>>&) override;
         void Render(const RenderPacket& packet) override;
 
         // ProjectedShadowFeatureProcessorInterface overrides ...

Gems/Atom/RPI/Code/Include/Atom/RPI.Public/FeatureProcessor.h

@@ -48,9 +48,10 @@ namespace AZ
             friend class Scene;
         public:
 
-            // [GFX TODO]: now these structure are empty, but we will clean up them later when we are sure we won't have any members in them.
+        public:
             struct PrepareViewsPacket
             {
+                AZStd::map<ViewPtr, RHI::DrawListMask> m_persistentViews;
             };
 
             struct SimulatePacket
@@ -105,7 +106,8 @@ namespace AZ
             //! views (transient views) are views that must be rendered only to correctly render 
             //! the main views. This function is called per frame and it happens on main thread.
             //! Support views should be added to outViews with their associated pipeline view tags.
-            virtual void PrepareViews(const PrepareViewsPacket&, AZStd::vector<AZStd::pair<PipelineViewTag, ViewPtr>>& /* outViews*/) {}
+            virtual void PrepareViews(
+                const PrepareViewsPacket& /*prepareViewPacket*/, AZStd::vector<AZStd::pair<PipelineViewTag, ViewPtr>>& /*outViews*/) {}
 
             //! The feature processor should perform any internal simulation at this point - For 
             //! instance, updating a particle system or animation. Not every feature processor

Gems/Atom/RPI/Code/Source/RPI.Public/Scene.cpp

@@ -786,6 +786,7 @@ namespace AZ
 
                 // Collect transient views from each feature processor
                 FeatureProcessor::PrepareViewsPacket prepareViewPacket;
+                prepareViewPacket.m_persistentViews = persistentViews;
                 AZStd::vector<AZStd::pair<PipelineViewTag, ViewPtr>> transientViews;
                 for (auto& fp : m_featureProcessors)
                 {