Hierarchical Variance Screen Space Shadows. Backing up current state. Cascade logic is almost done being setup now - so quality isnt there quite yet, but the full algorithm is implemented.

HVSSS Cascades all setup and working. Added high quality filter modes. Need to expose these as toggleable keywords. Need to expose sample count as tuneable parameter. Need to cleanup some code.

More iteration

Backing up latest work. Includes general code cleanup, as well as more robust handling of depth buffer thickness heuristic

Added support for mip bias while raymarching depth lods. Set our sample count back to 10

Only apply HVSSS in Deferred or Forward passes (skips things like DynamicGI and Volumetrics - for now). Forward is a little bit of a hack, it assumes that the depth of the forward renderered geometry is the same or very similar to the depth buffer depth. For opaque surfaces, this is true because depth prepass is enabled. For transparent objects this is not necessarily true. Lets see how this goes.

Remove HVSSS keywords. Not using a variant for HVSSS.

Stop using uint[4] for compute parameters, use a Vector4 instead. While the data is technically uint, its not worth the hassle of managing heap allocated arrays to pass the data through. RenderGraph does have an API to allow temporary allocations of arrays for this purpose, but it still feels like overkill. We dont need the precision of full uint. a float gives us 2^24 exact integers, which is enough for our use case.

Fix up bilateral filtering. Added optional screen space vignette. Added fullscreen debug view. Fixed cpu uint[] -> Vector4 conversion logic

HVSSS F16 Support

HVSSS: Cleanup to raymarch loop. Evaluating 4x samples per loop iteration to help hide TEX unit latency.

Implemented R16G16B16A16_UNorm discretized version of moments shadow mapping for HVSSS - seems to out perform even R32G32_SFloat VSM (more robust shadows / far less edge artifacts). Still havent gotten a nicely working implementation of the thickness heuristic for Moments, but maybe thats not important for our look afterall.

Bugfix to view space depth calculation during light range limit cpu side. Tuned output of moments shadow data to avoid light gray areas dominating the screen in certain self intersection cases (by clipping off the top of the distribution)

Got a tuned thickness that feels pretty good with moments, and makes intuitive sense

Move HVSSS related rendergraph data and functions into its own partial HDRenderPipeline class.

spacing

Minor include cleanup

Break HVSSSModes into different kernels so they can be toggled at runtime.

HVSSS: More work exposing parameters

HVSSS: Cleanup to raymarch setup code

Fix bug in VSM32 linear initialization

HVSSS: More stabilizing of depth thickness heuristic across all parameter settings

HVSSS: More cleanup to dither

HVSSS Dither Bugfix

HVSSS: Cleanup to Transmission Accumulator. Additionally, early out if center pixel is outside of light range. Additionally, do not self shadow during raymarching (cleaned up a bunch of 1 pixel artifacts).

HVSSS: More fixes to the transmissive accumulator

HVSSS: Different base thickness scales for VSM32, VSM16, and Moments

HVSSS: Retune defaults

HVSSS: Bugfixes to VSM16 brings its quality to almost visually identical to VSM32

HVSSS: Disable debug symbols

Add #if defined(SHADERPASS) guards to HVSSS sampling - previously if SHADERPASS wasnt defined at all HVSSS could also be enabled

HVSSS another define guard

tweaked hvsss defaults

Author: pastasfuture

com.unity.render-pipelines.high-definition/Editor/Lighting/HDLightUI.Skin.cs

@@ -17,6 +17,7 @@ sealed class Styles
             public readonly GUIContent shadowHeader = new GUIContent("Shadows");
             public readonly GUIContent shadowMapSubHeader = new GUIContent("Shadow Map");
             public readonly GUIContent contactShadowsSubHeader = new GUIContent("Contact Shadows");
+            public readonly GUIContent hiearchicalVarianceScreenSpaceShadowsSubHeader = new GUIContent("Hierarchical Variance Screen Space Shadows");
             public readonly GUIContent bakedShadowsSubHeader = new GUIContent("Baked Shadows");
             public readonly GUIContent veryHighShadowQualitySubHeader = new GUIContent("Very High Quality Settings");
             public readonly GUIContent highShadowQualitySubHeader = new GUIContent("High Quality Settings");
@@ -148,6 +149,8 @@ sealed class Styles
             public readonly GUIContent evsmLightLeakBias = new GUIContent("Light Leak Bias", "Increasing this value light leaking, but it eats up a bit of the softness of the shadow.");
             public readonly GUIContent evsmVarianceBias = new GUIContent("Variance Bias", "Variance Bias for EVSM. This is to contrast numerical accuracy issues. ");
             public readonly GUIContent evsmAdditionalBlurPasses = new GUIContent("Blur passes", "Increasing this will increase the softness of the shadow, but it will severely impact performance.");
+            public readonly GUIContent useHierarchicalVarianceScreenSpaceShadows = new GUIContent("Enable", "Reccomended to only use for hero lights like character shadow casters.");
+            public readonly GUIContent hierarchicalVarianceScreenSpaceShadowsPenumbraRadius = new GUIContent("Penumbra Radius", "Controls softness of HVSSS shadows. Parameterized in meters around the light source (think spherical area lights).");
 
             // Very high shadow settings
             public readonly GUIContent lightAngle = new GUIContent("Light Angle");

com.unity.render-pipelines.high-definition/Editor/Lighting/HDLightUI.cs

@@ -45,6 +45,7 @@ enum Expandable
             BakedShadow = 1 << 7,
             ShadowQuality = 1 << 8,
             CelestialBody = 1 << 9,
+            HierarchicalVarianceScreenSpaceShadows = 1 << 10
         }
 
         enum AdvancedMode
@@ -135,7 +136,9 @@ static HDLightUI()
                                 CED.Conditional((serialized, owner) => HasShadowQualitySettingsUI(HDShadowFilteringQuality.Low, serialized, owner),
                                     CED.FoldoutGroup(s_Styles.lowShadowQualitySubHeader, Expandable.ShadowQuality, k_ExpandedState, FoldoutOption.SubFoldout | FoldoutOption.Indent, DrawLowShadowSettingsContent)),
                                 CED.Conditional((serialized, owner) => serialized.type != HDLightType.Area,
-                                    CED.FoldoutGroup(s_Styles.contactShadowsSubHeader, Expandable.ContactShadow, k_ExpandedState, FoldoutOption.SubFoldout | FoldoutOption.Indent | FoldoutOption.NoSpaceAtEnd, DrawContactShadowsContent)
+                                    CED.FoldoutGroup(s_Styles.contactShadowsSubHeader, Expandable.ContactShadow, k_ExpandedState, FoldoutOption.SubFoldout | FoldoutOption.Indent | FoldoutOption.NoSpaceAtEnd, DrawContactShadowsContent)),
+                                CED.Conditional((serialized, owner) => serialized.type == HDLightType.Point || serialized.type == HDLightType.Spot,
+                                    CED.FoldoutGroup(s_Styles.hiearchicalVarianceScreenSpaceShadowsSubHeader, Expandable.HierarchicalVarianceScreenSpaceShadows, k_ExpandedState, FoldoutOption.SubFoldout | FoldoutOption.Indent | FoldoutOption.NoSpaceAtEnd, DrawHierarchicalVarianceScreenSpaceShadowsContent)
                                 )
                             ),
                             CED.noop //will only add parameter in first sub header
@@ -1262,6 +1265,24 @@ static void DrawContactShadowsContent(SerializedHDLight serialized, Editor owner
             }
         }
 
+        static void DrawHierarchicalVarianceScreenSpaceShadowsContent(SerializedHDLight serialized, Editor owner)
+        {
+            HDLightType lightType = serialized.type;
+
+            // For the moment, we only support hierarchical variance screen space shadows for point and spot lights. Might be interesting to extend to area lights (but not a priority).
+            if ((lightType == HDLightType.Point) || (lightType == HDLightType.Spot) && HDRenderPipeline.pipelineSupportsHierarchicalVarianceScreenSpaceShadows)
+            {
+                EditorGUILayout.PropertyField(serialized.useHierarchicalVarianceScreenSpaceShadows, s_Styles.useHierarchicalVarianceScreenSpaceShadows);
+
+                using (new EditorGUI.DisabledScope(!serialized.useHierarchicalVarianceScreenSpaceShadows.boolValue))
+                {
+                    EditorGUI.indentLevel++;
+                    EditorGUILayout.PropertyField(serialized.hierarchicalVarianceScreenSpaceShadowsPenumbraRadius, s_Styles.hierarchicalVarianceScreenSpaceShadowsPenumbraRadius);
+                    EditorGUI.indentLevel--;
+                }
+            }
+        }
+
         static void DrawBakedShadowsContent(SerializedHDLight serialized, Editor owner)
         {
             DrawEnableShadowMap(serialized, owner);

com.unity.render-pipelines.high-definition/Editor/Lighting/SerializedHDLight.cs

@@ -50,6 +50,8 @@ internal class SerializedHDLight
         public SerializedProperty useCustomSpotLightShadowCone;
         public SerializedProperty customSpotLightShadowCone;
         public SerializedProperty useScreenSpaceShadows;
+        public SerializedProperty useHierarchicalVarianceScreenSpaceShadows;
+        public SerializedProperty hierarchicalVarianceScreenSpaceShadowsPenumbraRadius;
         public SerializedProperty interactsWithSky;
         public SerializedProperty angularDiameter;
         public SerializedProperty flareSize;
@@ -368,6 +370,8 @@ public SerializedHDLight(HDAdditionalLightData[] lightDatas, LightEditor.Setting
                 useCustomSpotLightShadowCone = o.Find("m_UseCustomSpotLightShadowCone");
                 customSpotLightShadowCone = o.Find("m_CustomSpotLightShadowCone");
                 useScreenSpaceShadows = o.Find("m_UseScreenSpaceShadows");
+                useHierarchicalVarianceScreenSpaceShadows = o.Find("m_UseHierarchicalVarianceScreenSpaceShadows");
+                hierarchicalVarianceScreenSpaceShadowsPenumbraRadius = o.Find("m_HierarchicalVarianceScreenSpaceShadowsPenumbraRadius");
                 interactsWithSky = o.Find("m_InteractsWithSky");
                 angularDiameter = o.Find("m_AngularDiameter");
                 flareSize = o.Find("m_FlareSize");

com.unity.render-pipelines.high-definition/Editor/RenderPipeline/HDRenderPipelineUI.Skin.cs

@@ -202,6 +202,7 @@ public class GeneralSection
 
             public static readonly GUIContent useContactShadows = EditorGUIUtility.TrTextContent("Use Contact Shadows", "Use contact shadows for lights.");
             public static readonly GUIContent supportScreenSpaceShadows = EditorGUIUtility.TrTextContent("Screen Space Shadows", "Enables the support of screen space shadows in HDRP.");
+            public static readonly GUIContent supportHierarchicalVarianceScreenSpaceShadows = EditorGUIUtility.TrTextContent("Hierarchical Variance Screen Space Shadows", "Enables the support of hierarhical variance screen space shadows in HDRP.");
             public static readonly GUIContent maxScreenSpaceShadowSlots = EditorGUIUtility.TrTextContent("Maximum", "Sets the maximum number of screen space shadows slots HDRP can handle on screen at once. Opaque shadows requires one slot, color shadow requires three.");
             public static readonly GUIContent screenSpaceShadowFormat = EditorGUIUtility.TrTextContent("Buffer Format", "Defines the format of the buffer used for screen space shadows. The buffer format can be R8G8B8A8 or R16G16B16A16.");
             public static readonly GUIContent maxShadowResolution = EditorGUIUtility.TrTextContent("Max shadow resolution", "Specifies the maximum resolution for any single shadow map.");

com.unity.render-pipelines.high-definition/Editor/RenderPipeline/HDRenderPipelineUI.cs

@@ -373,6 +373,8 @@ static void Drawer_SectionShadows(SerializedHDRenderPipelineAsset serialized, Ed
                 --EditorGUI.indentLevel;
             }
 
+            EditorGUILayout.PropertyField(serialized.renderPipelineSettings.hdShadowInitParams.supportHierarchicalVarianceScreenSpaceShadows, Styles.supportHierarchicalVarianceScreenSpaceShadows);
+
             SerializedScalableSettingUI.ValueGUI<bool>(serialized.renderPipelineSettings.lightSettings.useContactShadows, Styles.useContactShadows);
 
             m_ShowDirectionalLightSection = EditorGUILayout.Foldout(m_ShowDirectionalLightSection, Styles.directionalShadowsSubTitle, true);

com.unity.render-pipelines.high-definition/Editor/RenderPipeline/Settings/FrameSettingsUI.Drawers.cs

@@ -344,6 +344,7 @@ static void Drawer_SectionLightingSettings(SerializedFrameSettings serialized, E
             area.AmmendInfo(FrameSettingsField.ProbeVolume, overrideable: () => hdrpSettings.supportProbeVolume);
             area.AmmendInfo(FrameSettingsField.ProbeVolumeDynamicGI, overrideable: () => hdrpSettings.supportProbeVolumeDynamicGI);
             area.AmmendInfo(FrameSettingsField.ScreenSpaceShadows, overrideable: () => hdrpSettings.hdShadowInitParams.supportScreenSpaceShadows);
+            area.AmmendInfo(FrameSettingsField.HierarchicalVarianceScreenSpaceShadows, overrideable: () => hdrpSettings.hdShadowInitParams.supportHierarchicalVarianceScreenSpaceShadows);
             area.Draw(withOverride);
         }
 

com.unity.render-pipelines.high-definition/Editor/RenderPipeline/Settings/SerializedHDShadowInitParameters.cs

@@ -33,6 +33,7 @@ class SerializedHDShadowInitParameters
         public SerializedProperty shadowFilteringQuality;
 
         public SerializedProperty supportScreenSpaceShadows;
+        public SerializedProperty supportHierarchicalVarianceScreenSpaceShadows;
         public SerializedProperty maxScreenSpaceShadowSlots;
         public SerializedProperty screenSpaceShadowBufferFormat;
 
@@ -65,6 +66,7 @@ public SerializedHDShadowInitParameters(SerializedProperty root)
 
             shadowFilteringQuality = root.Find((HDShadowInitParameters s) => s.shadowFilteringQuality);
             supportScreenSpaceShadows = root.Find((HDShadowInitParameters s) => s.supportScreenSpaceShadows);
+            supportHierarchicalVarianceScreenSpaceShadows = root.Find((HDShadowInitParameters s) => s.supportHierarchicalVarianceScreenSpaceShadows);
             maxScreenSpaceShadowSlots = root.Find((HDShadowInitParameters s) => s.maxScreenSpaceShadowSlots);
             screenSpaceShadowBufferFormat = root.Find((HDShadowInitParameters s) => s.screenSpaceShadowBufferFormat);
         }

com.unity.render-pipelines.high-definition/Runtime/Debug/DebugDisplay.cs

@@ -77,6 +77,8 @@ public enum FullScreenDebugMode
         DepthPyramid,
         /// <summary>Display the final color pyramid for the frame.</summary>
         FinalColorPyramid,
+        /// <summary>Display Hierarchical Variance Screen Space Shadows buffer.</summary>
+        HierarchicalVarianceScreenSpaceShadows,
 
         // Raytracing Only
         /// <summary>Display ray tracing light cluster.</summary>
@@ -129,7 +131,7 @@ public enum FullScreenDebugMode
         /// <summary>Display Screen Space Reflections buffer of the previous frame accumulated.</summary>
         ScreenSpaceReflectionsPrev,
         /// <summary>Display Screen Space Reflections buffer of the current frame hit.</summary>
-        ScreenSpaceReflectionsAccum
+        ScreenSpaceReflectionsAccum,
     }
 
     /// <summary>
@@ -640,6 +642,11 @@ public void SetFullScreenDebugMode(FullScreenDebugMode value)
             data.fullScreenDebugMode = value;
         }
 
+        public FullScreenDebugMode GetFullScreenDebugMode()
+        {
+            return data.fullScreenDebugMode;
+        }
+
         /// <summary>
         /// Set the current Shadow Map Debug Mode.
         /// </summary>

com.unity.render-pipelines.high-definition/Runtime/Debug/DebugDisplay.cs.hlsl

@@ -18,29 +18,30 @@
 #define FULLSCREENDEBUGMODE_PRE_REFRACTION_COLOR_PYRAMID (8)
 #define FULLSCREENDEBUGMODE_DEPTH_PYRAMID (9)
 #define FULLSCREENDEBUGMODE_FINAL_COLOR_PYRAMID (10)
-#define FULLSCREENDEBUGMODE_LIGHT_CLUSTER (11)
-#define FULLSCREENDEBUGMODE_SCREEN_SPACE_GLOBAL_ILLUMINATION (12)
-#define FULLSCREENDEBUGMODE_RECURSIVE_RAY_TRACING (13)
-#define FULLSCREENDEBUGMODE_RAY_TRACED_SUB_SURFACE (14)
-#define FULLSCREENDEBUGMODE_MAX_LIGHTING_FULL_SCREEN_DEBUG (15)
-#define FULLSCREENDEBUGMODE_MIN_RENDERING_FULL_SCREEN_DEBUG (16)
-#define FULLSCREENDEBUGMODE_MOTION_VECTORS (17)
-#define FULLSCREENDEBUGMODE_NAN_TRACKER (18)
-#define FULLSCREENDEBUGMODE_COLOR_LOG (19)
-#define FULLSCREENDEBUGMODE_GRAYSCALE (20)
-#define FULLSCREENDEBUGMODE_DEPTH_OF_FIELD_COC (21)
-#define FULLSCREENDEBUGMODE_TRANSPARENCY_OVERDRAW (22)
-#define FULLSCREENDEBUGMODE_QUAD_OVERDRAW (23)
-#define FULLSCREENDEBUGMODE_VERTEX_DENSITY (24)
-#define FULLSCREENDEBUGMODE_REQUESTED_VIRTUAL_TEXTURE_TILES (25)
-#define FULLSCREENDEBUGMODE_MAX_RENDERING_FULL_SCREEN_DEBUG (26)
-#define FULLSCREENDEBUGMODE_MIN_MATERIAL_FULL_SCREEN_DEBUG (27)
-#define FULLSCREENDEBUGMODE_VALIDATE_DIFFUSE_COLOR (28)
-#define FULLSCREENDEBUGMODE_VALIDATE_SPECULAR_COLOR (29)
-#define FULLSCREENDEBUGMODE_HEIGHTMAPS (30)
-#define FULLSCREENDEBUGMODE_MAX_MATERIAL_FULL_SCREEN_DEBUG (31)
-#define FULLSCREENDEBUGMODE_SCREEN_SPACE_REFLECTIONS_PREV (32)
-#define FULLSCREENDEBUGMODE_SCREEN_SPACE_REFLECTIONS_ACCUM (33)
+#define FULLSCREENDEBUGMODE_HIERARCHICAL_VARIANCE_SCREEN_SPACE_SHADOWS (11)
+#define FULLSCREENDEBUGMODE_LIGHT_CLUSTER (12)
+#define FULLSCREENDEBUGMODE_SCREEN_SPACE_GLOBAL_ILLUMINATION (13)
+#define FULLSCREENDEBUGMODE_RECURSIVE_RAY_TRACING (14)
+#define FULLSCREENDEBUGMODE_RAY_TRACED_SUB_SURFACE (15)
+#define FULLSCREENDEBUGMODE_MAX_LIGHTING_FULL_SCREEN_DEBUG (16)
+#define FULLSCREENDEBUGMODE_MIN_RENDERING_FULL_SCREEN_DEBUG (17)
+#define FULLSCREENDEBUGMODE_MOTION_VECTORS (18)
+#define FULLSCREENDEBUGMODE_NAN_TRACKER (19)
+#define FULLSCREENDEBUGMODE_COLOR_LOG (20)
+#define FULLSCREENDEBUGMODE_GRAYSCALE (21)
+#define FULLSCREENDEBUGMODE_DEPTH_OF_FIELD_COC (22)
+#define FULLSCREENDEBUGMODE_TRANSPARENCY_OVERDRAW (23)
+#define FULLSCREENDEBUGMODE_QUAD_OVERDRAW (24)
+#define FULLSCREENDEBUGMODE_VERTEX_DENSITY (25)
+#define FULLSCREENDEBUGMODE_REQUESTED_VIRTUAL_TEXTURE_TILES (26)
+#define FULLSCREENDEBUGMODE_MAX_RENDERING_FULL_SCREEN_DEBUG (27)
+#define FULLSCREENDEBUGMODE_MIN_MATERIAL_FULL_SCREEN_DEBUG (28)
+#define FULLSCREENDEBUGMODE_VALIDATE_DIFFUSE_COLOR (29)
+#define FULLSCREENDEBUGMODE_VALIDATE_SPECULAR_COLOR (30)
+#define FULLSCREENDEBUGMODE_HEIGHTMAPS (31)
+#define FULLSCREENDEBUGMODE_MAX_MATERIAL_FULL_SCREEN_DEBUG (32)
+#define FULLSCREENDEBUGMODE_SCREEN_SPACE_REFLECTIONS_PREV (33)
+#define FULLSCREENDEBUGMODE_SCREEN_SPACE_REFLECTIONS_ACCUM (34)
 
 // Generated from UnityEngine.Rendering.HighDefinition.ShaderVariablesDebugDisplay
 // PackingRules = Exact

com.unity.render-pipelines.high-definition/Runtime/Debug/DebugFullScreen.shader

@@ -412,6 +412,10 @@ Shader "Hidden/HDRP/DebugFullScreen"
                     return float4(HsvToRgb(hsv), 1.0f);
 
                 }
+                if (_FullScreenDebugMode == FULLSCREENDEBUGMODE_HIERARCHICAL_VARIANCE_SCREEN_SPACE_SHADOWS)
+                {
+                    return SRGBToLinear(SAMPLE_TEXTURE2D_X(_DebugFullScreenTexture, s_point_clamp_sampler, input.texcoord).xxxx);
+                }
 
                 return float4(0.0, 0.0, 0.0, 0.0);
             }