Exposing esm exponent

Gems/Atom/Feature/Common/Assets/ShaderLib/Atom/Features/Shadow/ProjectedShadow.azsli

@@ -226,7 +226,7 @@ float ProjectedShadow::GetVisibilityEsm()
     }
 
     const float invAtlasSize = ViewSrg::m_invShadowmapAtlasSize;
-    const Texture2DArray<float> expShadowmap = PassSrg::m_projectedExponentialShadowmap;
+    const Texture2DArray<float> shadowmap = PassSrg::m_projectedExponentialShadowmap;
 
     if (m_shadowPosition.x >= 0 && m_shadowPosition.x * size < size - PixelMargin &&
         m_shadowPosition.y >= 0 && m_shadowPosition.y * size < size - PixelMargin)
@@ -243,10 +243,12 @@ float ProjectedShadow::GetVisibilityEsm()
         const float depth = PerspectiveDepthToLinear(
             m_shadowPosition.z, 
             coefficients);
-        const float expDepthInShadowmap = expShadowmap.Sample(
+        const float occluder = shadowmap.Sample(
             PassSrg::LinearSampler, 
             float3(atlasPosition.xy * invAtlasSize, atlasPosition.z)).r;
-        const float ratio = exp(-EsmExponentialShift * depth) * expDepthInShadowmap;
+   
+        const float exponent = -ViewSrg::m_projectedShadows[m_shadowIndex].m_esmExponent * (depth - occluder);        
+        const float ratio = exp(exponent);
         // pow() mitigates light bleeding to shadows from near shadow casters.
         return saturate( pow(ratio, 8) );
     }
@@ -265,7 +267,7 @@ float ProjectedShadow::GetVisibilityEsmPcf()
     }
 
     const float invAtlasSize = ViewSrg::m_invShadowmapAtlasSize;
-    const Texture2DArray<float> expShadowmap = PassSrg::m_projectedExponentialShadowmap;
+    const Texture2DArray<float> shadowmap = PassSrg::m_projectedExponentialShadowmap;
 
     if (m_shadowPosition.x >= 0 && m_shadowPosition.x * size < size - PixelMargin &&
         m_shadowPosition.y >= 0 && m_shadowPosition.y * size < size - PixelMargin)
@@ -282,10 +284,12 @@ float ProjectedShadow::GetVisibilityEsmPcf()
         const float depth = PerspectiveDepthToLinear(
             m_shadowPosition.z,
             coefficients);
-        const float expDepthInShadowmap = expShadowmap.Sample(
+        const float occluder = shadowmap.Sample(
             PassSrg::LinearSampler,
             float3(atlasPosition.xy * invAtlasSize, atlasPosition.z)).r;
-        float ratio = exp(-EsmExponentialShift * depth) * expDepthInShadowmap;
+     
+        const float exponent = -ViewSrg::m_projectedShadows[m_shadowIndex].m_esmExponent * (depth - occluder);        
+        float ratio = exp(exponent);
 
         static const float pcfFallbackThreshold = 1.04;
         if (ratio > pcfFallbackThreshold)

Gems/Atom/Feature/Common/Assets/ShaderResourceGroups/CoreLights/ViewSrg.azsli

@@ -92,6 +92,8 @@ partial ShaderResourceGroup ViewSrg
         uint m_filteringSampleCount;
         float2 m_unprojectConstants;
         float m_bias;
+        float m_esmExponent;
+        float3 m_padding;
     };
 
     StructuredBuffer<ProjectedShadow> m_projectedShadows;

Gems/Atom/Feature/Common/Assets/Shaders/Shadow/DepthExponentiation.azsl

@@ -69,8 +69,15 @@ void MainCS(uint3 dispatchId: SV_DispatchThreadID)
             // So this converts it to "depth" to emphasize the difference
             // within the frustum.
             depth = (depthInClip - distanceMin) / (1. - distanceMin);
-        }
+
+            // Todo: Expose Esm exponent slider for directional lights
+            // This would remove the exp calculation below, collapsing it into a subtraction in DirectionalLightShadow.azsli
+            // ATOM-15775 
+            const float outValue = exp(EsmExponentialShift * depth);
+            PassSrg::m_outputShadowmap[dispatchId].r = outValue;
             break;
+
+        }
         case ShadowmapLightType::Spot:
         {
             const float3 coefficients = float3(
@@ -84,12 +91,9 @@ void MainCS(uint3 dispatchId: SV_DispatchThreadID)
             // and it often causes light bleeding with ESM.
             // So this converts it to a linear depth to emphasize the 
             // difference like a orthogonal depth.
-            depth = PerspectiveDepthToLinear(depthInClip, coefficients);
-        }
+            PassSrg::m_outputShadowmap[dispatchId].r = PerspectiveDepthToLinear(depthInClip, coefficients);
             break;
+        }
     }
-
-    const float outValue = exp(EsmExponentialShift * depth);
-    PassSrg::m_outputShadowmap[dispatchId].r = outValue;
 }
 

Gems/Atom/Feature/Common/Code/Include/Atom/Feature/CoreLights/DiskLightFeatureProcessorInterface.h

@@ -100,10 +100,13 @@ namespace AZ
             virtual void SetFilteringSampleCount(LightHandle handle, uint16_t count) = 0;
             //! Sets the shadowmap Pcf (percentage closer filtering) method.
             virtual void SetPcfMethod(LightHandle handle, PcfMethod method) = 0;
+            //! Sets the Esm exponent to use. Higher values produce a steeper falloff in the border areas between light and shadow.
+			virtual void SetEsmExponent(LightHandle handle, float exponent) = 0;
 
             //! Sets all of the the disk data for the provided LightHandle.
             virtual void SetDiskData(LightHandle handle, const DiskLightData& data) = 0;
-            
+
+
         };
     } // namespace Render
 } // namespace AZ

Gems/Atom/Feature/Common/Code/Include/Atom/Feature/CoreLights/PointLightFeatureProcessorInterface.h

@@ -82,6 +82,8 @@ namespace AZ
             virtual void SetFilteringSampleCount(LightHandle handle, uint16_t count) = 0;
             //! Sets the shadowmap Pcf (percentage closer filtering) method.
             virtual void SetPcfMethod(LightHandle handle, PcfMethod method) = 0;
+            //! Sets the Esm exponent to use. Higher values produce a steeper falloff in the border areas between light and shadow.
+            virtual void SetEsmExponent(LightHandle handle, float exponent) = 0;
             //! Sets all of the the point data for the provided LightHandle.
             virtual void SetPointData(LightHandle handle, const PointLightData& data) = 0;
         };

Gems/Atom/Feature/Common/Code/Source/CoreLights/DiskLightFeatureProcessor.cpp

@@ -343,6 +343,11 @@ namespace AZ
             SetShadowSetting(handle, &ProjectedShadowFeatureProcessor::SetPcfMethod, method);
         }
 
+        void DiskLightFeatureProcessor::SetEsmExponent(LightHandle handle, float exponent)
+        {
+            SetShadowSetting(handle, &ProjectedShadowFeatureProcessor::SetEsmExponent, exponent);
+        }
+
         void DiskLightFeatureProcessor::UpdateShadow(LightHandle handle)
         {
             const DiskLightData& diskLight = m_diskLightData.GetData(handle.GetIndex());

Gems/Atom/Feature/Common/Code/Source/CoreLights/DiskLightFeatureProcessor.h

@@ -60,6 +60,7 @@ namespace AZ
             void SetPredictionSampleCount(LightHandle handle, uint16_t count) override;
             void SetFilteringSampleCount(LightHandle handle, uint16_t count) override;
             void SetPcfMethod(LightHandle handle, PcfMethod method) override;
+            void SetEsmExponent(LightHandle handle, float esmExponent) override;
 
             void SetDiskData(LightHandle handle, const DiskLightData& data) override;
 

Gems/Atom/Feature/Common/Code/Source/CoreLights/PointLightFeatureProcessor.cpp

@@ -312,5 +312,10 @@ namespace AZ
             SetShadowSetting(handle, &ProjectedShadowFeatureProcessor::SetPcfMethod, method);
         }
 
+        void PointLightFeatureProcessor::SetEsmExponent(LightHandle handle, float esmExponent)
+        {
+            SetShadowSetting(handle, &ProjectedShadowFeatureProcessor::SetEsmExponent, esmExponent);
+        }
+
     } // namespace Render
 } // namespace AZ

Gems/Atom/Feature/Common/Code/Source/CoreLights/PointLightFeatureProcessor.h

@@ -57,6 +57,7 @@ namespace AZ
             void SetPredictionSampleCount(LightHandle handle, uint16_t count) override;
             void SetFilteringSampleCount(LightHandle handle, uint16_t count) override;
             void SetPcfMethod(LightHandle handle, PcfMethod method) override;
+            void SetEsmExponent(LightHandle handle, float esmExponent) override;
             void SetPointData(LightHandle handle, const PointLightData& data) override;
 
             const Data::Instance<RPI::Buffer>  GetLightBuffer() const;

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

@@ -168,6 +168,13 @@ namespace AZ::Render
         m_deviceBufferNeedsUpdate = true;
     }
 
+    void ProjectedShadowFeatureProcessor::SetEsmExponent(ShadowId id, float exponent)
+    {
+        ShadowData& shadowData = m_shadowData.GetElement<ShadowDataIndex>(id.GetIndex());
+        shadowData.m_esmExponent = exponent;
+        m_deviceBufferNeedsUpdate = true;
+    }
+
     void ProjectedShadowFeatureProcessor::SetShadowFilterMethod(ShadowId id, ShadowFilterMethod method)
     {
         AZ_Assert(id.IsValid(), "Invalid ShadowId passed to ProjectedShadowFeatureProcessor::SetShadowFilterMethod().");

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

@@ -52,6 +52,7 @@ namespace AZ::Render
         void SetFieldOfViewY(ShadowId id, float fieldOfViewYRadians) override;
         void SetShadowmapMaxResolution(ShadowId id, ShadowmapSize size) override;
         void SetPcfMethod(ShadowId id, PcfMethod method);
+        void SetEsmExponent(ShadowId id, float exponent);
         void SetShadowFilterMethod(ShadowId id, ShadowFilterMethod method) override;
         void SetSofteningBoundaryWidthAngle(ShadowId id, float boundaryWidthRadians) override;
         void SetPredictionSampleCount(ShadowId id, uint16_t count) override;
@@ -73,6 +74,8 @@ namespace AZ::Render
             uint32_t m_filteringSampleCount = 0;
             AZStd::array<float, 2> m_unprojectConstants = { {0, 0} };
             float m_bias;
+            float m_esmExponent = 87.0f;
+            float m_padding[3];
         };
 
         // CPU data used for constructing & updating ShadowData

Gems/AtomLyIntegration/CommonFeatures/Code/Include/AtomLyIntegration/CommonFeatures/CoreLights/AreaLightBus.h

@@ -143,6 +143,13 @@ namespace AZ
 
             //! Sets the type of Pcf (percentage-closer filtering) to use.
             virtual void SetPcfMethod(PcfMethod method) = 0;
+
+            //! Gets the Esm exponent. Higher values produce a steeper falloff between light and shadow.
+            virtual float GetEsmExponent() const = 0;
+
+            //! Sets the Esm exponent. Higher values produce a steeper falloff between light and shadow.
+            virtual void SetEsmExponent(float exponent) = 0;
+
         };
 
         //! The EBus for requests to for setting and getting light component properties.

Gems/AtomLyIntegration/CommonFeatures/Code/Include/AtomLyIntegration/CommonFeatures/CoreLights/AreaLightComponentConfig.h

@@ -66,6 +66,7 @@ namespace AZ
             float m_boundaryWidthInDegrees = 0.25f;
             uint16_t m_predictionSampleCount = 4;
             uint16_t m_filteringSampleCount = 12;
+            float m_esmExponent = 87.0f;
 
             // The following functions provide information to an EditContext...
 
@@ -124,6 +125,8 @@ namespace AZ
             //! Returns true if pcf boundary search is disabled.
             bool IsPcfBoundarySearchDisabled() const;
 
+            //! Returns true if exponential shadow maps are disabled.
+            bool IsEsmDisabled() const;
         };
     }
 }

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/AreaLightComponentConfig.cpp

@@ -21,7 +21,7 @@ namespace AZ
             if (auto serializeContext = azrtti_cast<AZ::SerializeContext*>(context))
             {
                 serializeContext->Class<AreaLightComponentConfig, ComponentConfig>()
-                    ->Version(5) // ATOM-14637
+                    ->Version(6) // ATOM-15654
                     ->Field("LightType", &AreaLightComponentConfig::m_lightType)
                     ->Field("Color", &AreaLightComponentConfig::m_color)
                     ->Field("IntensityMode", &AreaLightComponentConfig::m_intensityMode)
@@ -41,7 +41,8 @@ namespace AZ
                     ->Field("Softening Boundary Width", &AreaLightComponentConfig::m_boundaryWidthInDegrees)
                     ->Field("Prediction Sample Count", &AreaLightComponentConfig::m_predictionSampleCount)
                     ->Field("Filtering Sample Count", &AreaLightComponentConfig::m_filteringSampleCount)
-                    ->Field("Pcf Method", &AreaLightComponentConfig::m_pcfMethod);
+                    ->Field("Pcf Method", &AreaLightComponentConfig::m_pcfMethod)
+                    ->Field("Esm Exponent", &AreaLightComponentConfig::m_esmExponent)
                     ;
             }
         }
@@ -200,5 +201,11 @@ namespace AZ
 
             return m_pcfMethod != PcfMethod::BoundarySearch;
         }
+
+        bool AreaLightComponentConfig::IsEsmDisabled() const
+        {
+            return !(m_shadowFilterMethod == ShadowFilterMethod::Esm || m_shadowFilterMethod == ShadowFilterMethod::EsmPcf);
+        }
+
     }
 }

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/AreaLightComponentController.cpp

@@ -84,7 +84,9 @@ namespace AZ::Render
                 ->Event("SetFilteringSampleCount", &AreaLightRequestBus::Events::SetFilteringSampleCount)
                 ->Event("GetPcfMethod", &AreaLightRequestBus::Events::GetPcfMethod)
                 ->Event("SetPcfMethod", &AreaLightRequestBus::Events::SetPcfMethod)
-            
+                ->Event("GetEsmExponent", &AreaLightRequestBus::Events::GetEsmExponent)
+                ->Event("SetEsmExponent", &AreaLightRequestBus::Events::SetEsmExponent)
+
                 ->VirtualProperty("AttenuationRadius", "GetAttenuationRadius", "SetAttenuationRadius")
                 ->VirtualProperty("Color", "GetColor", "SetColor")
                 ->VirtualProperty("EmitsLightBothDirections", "GetEmitsLightBothDirections", "SetEmitsLightBothDirections")
@@ -101,8 +103,9 @@ namespace AZ::Render
                 ->VirtualProperty("SofteningBoundaryWidthAngle", "GetSofteningBoundaryWidthAngle", "SetSofteningBoundaryWidthAngle")
                 ->VirtualProperty("PredictionSampleCount", "GetPredictionSampleCount", "SetPredictionSampleCount")
                 ->VirtualProperty("FilteringSampleCount", "GetFilteringSampleCount", "SetFilteringSampleCount")
-                ->VirtualProperty("PcfMethod", "GetPcfMethod", "SetPcfMethod");
-                ;
+                ->VirtualProperty("PcfMethod", "GetPcfMethod", "SetPcfMethod")
+                ->VirtualProperty("EsmExponent", "GetEsmExponent", "SetEsmExponent");
+            ;
         }
     }
 
@@ -314,6 +317,7 @@ namespace AZ::Render
                 m_lightShapeDelegate->SetPredictionSampleCount(m_configuration.m_predictionSampleCount);
                 m_lightShapeDelegate->SetFilteringSampleCount(m_configuration.m_filteringSampleCount);
                 m_lightShapeDelegate->SetPcfMethod(m_configuration.m_pcfMethod);
+                m_lightShapeDelegate->SetEsmExponent(m_configuration.m_esmExponent);
             }
         }
     }
@@ -565,6 +569,20 @@ namespace AZ::Render
         }
     }
 
+    float AreaLightComponentController::GetEsmExponent() const
+    {
+        return m_configuration.m_esmExponent;
+    }
+
+    void AreaLightComponentController::SetEsmExponent(float esmExponent)
+    {
+        m_configuration.m_esmExponent = esmExponent;
+        if (m_lightShapeDelegate)
+        {
+            m_lightShapeDelegate->SetEsmExponent(esmExponent);
+        }
+    }
+
     void AreaLightComponentController::CreateLightShapeDelegate()
     {
         switch (m_configuration.m_lightType)

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/AreaLightComponentController.h

@@ -92,6 +92,8 @@ namespace AZ
             void SetFilteringSampleCount(uint32_t count) override;
             PcfMethod GetPcfMethod() const override;
             void SetPcfMethod(PcfMethod method) override;
+            float GetEsmExponent() const override;
+            void SetEsmExponent(float exponent) override;
 
             void HandleDisplayEntityViewport(
                 const AzFramework::ViewportInfo& viewportInfo,

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/DiskLightDelegate.cpp

@@ -175,5 +175,13 @@ namespace AZ::Render
         }
     }
 
+    void DiskLightDelegate::SetEsmExponent(float exponent)
+    {
+        if (GetShadowsEnabled() && GetLightHandle().IsValid())
+        {
+            GetFeatureProcessor()->SetEsmExponent(GetLightHandle(), exponent);
+        }
+    }
+
     
 } // namespace AZ::Render

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/DiskLightDelegate.h

@@ -51,6 +51,7 @@ namespace AZ
             void SetPredictionSampleCount(uint32_t count) override;
             void SetFilteringSampleCount(uint32_t count) override;
             void SetPcfMethod(PcfMethod method) override;
+            void SetEsmExponent(float exponent) override;
 
         private:
 

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/EditorAreaLightComponent.cpp

@@ -179,8 +179,20 @@ namespace AZ
                             ->EnumAttribute(PcfMethod::BoundarySearch, "Boundary search")
                             ->Attribute(Edit::Attributes::ChangeNotify, Edit::PropertyRefreshLevels::ValuesOnly)
                             ->Attribute(Edit::Attributes::Visibility, &AreaLightComponentConfig::SupportsShadows)
-                            ->Attribute(Edit::Attributes::ReadOnly, &AreaLightComponentConfig::IsShadowPcfDisabled);
-                        ;
+                            ->Attribute(Edit::Attributes::ReadOnly, &AreaLightComponentConfig::IsShadowPcfDisabled) 
+                            ->Attribute(Edit::Attributes::ReadOnly, &AreaLightComponentConfig::IsShadowPcfDisabled) 
+                            ->DataElement(
+                            Edit::UIHandlers::Slider, &AreaLightComponentConfig::m_esmExponent, "Esm Exponent",
+                                "Exponent used by Esm shadows." 
+                                "Larger values increase the sharpness of the border between lit and unlit areas.") 
+                            ->Attribute(Edit::Attributes::Min, 50.0f)
+                            ->Attribute(Edit::Attributes::Max, 5000.0f) 
+                            ->Attribute(AZ::Edit::Attributes::Decimals, 0)
+                            ->Attribute(AZ::Edit::Attributes::SliderCurveMidpoint, 0.05)
+                            ->Attribute(Edit::Attributes::ChangeNotify, Edit::PropertyRefreshLevels::ValuesOnly) 
+                            ->Attribute(Edit::Attributes::Visibility, &AreaLightComponentConfig::SupportsShadows)
+                            ->Attribute(Edit::Attributes::ReadOnly, &AreaLightComponentConfig::IsEsmDisabled) 
+                            ;
                 }
             }
 

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/LightDelegateBase.h

@@ -63,6 +63,7 @@ namespace AZ
             void SetPredictionSampleCount([[maybe_unused]] uint32_t count) override {};
             void SetFilteringSampleCount([[maybe_unused]] uint32_t count) override {};
             void SetPcfMethod([[maybe_unused]] PcfMethod method) override {};
+            void SetEsmExponent([[maybe_unused]] float esmExponent) override{};
 
         protected:
             void InitBase(EntityId entityId);

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/LightDelegateInterface.h

@@ -85,6 +85,8 @@ namespace AZ
             virtual void SetFilteringSampleCount(uint32_t count) = 0;
             //! Sets the Pcf (Percentage closer filtering) method to use.
             virtual void SetPcfMethod(PcfMethod method) = 0;
+			//! Sets the Esm exponent to use. Higher values produce a steeper falloff between light and shadow.
+            virtual void SetEsmExponent(float exponent) = 0;
         };
     } //  namespace Render
 } // namespace AZ

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/SphereLightDelegate.cpp

@@ -122,5 +122,14 @@ namespace AZ
             }
         }
 
+        void SphereLightDelegate::SetEsmExponent(float esmExponent)
+        {
+            if (GetShadowsEnabled() && GetLightHandle().IsValid())
+            {
+                GetFeatureProcessor()->SetEsmExponent(GetLightHandle(), esmExponent);
+            }
+        }
+
+
     } // namespace Render
 } // namespace AZ

Gems/AtomLyIntegration/CommonFeatures/Code/Source/CoreLights/SphereLightDelegate.h

@@ -41,6 +41,7 @@ namespace AZ
             void SetPredictionSampleCount(uint32_t count) override;
             void SetFilteringSampleCount(uint32_t count) override;
             void SetPcfMethod(PcfMethod method) override;
+            void SetEsmExponent(float esmExponent) override;
 
         private: