Add shadowMap16Bit support

com.unity.render-pipelines.core/CoreRP/Shadow/ShadowBase.cs

 
         public int      shadowAtlasWidth = kDefaultShadowAtlasSize;
         public int      shadowAtlasHeight = kDefaultShadowAtlasSize;
+        public bool		shadowMap16Bit;
 
         public int      maxPointLightShadows = kDefaultMaxPointLightShadows;
         public int      maxSpotLightShadows = kDefaultMaxSpotLightShadows;

com.unity.render-pipelines.high-definition/CHANGELOG.md

 ### Added
 - Added a luminance meter in the debug menu
 - Added support of Light, reflection probe, emissive material, volume settings related to lighting to Lighting explorer
+- Added support for 16bit shadows
 
 ### Fixed
 - Fix issue with package upgrading (HDRP resources asset is now versionned to worarkound package manager limitation)

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

 
         public SerializedProperty shadowAtlasWidth;
         public SerializedProperty shadowAtlasHeight;
+        public SerializedProperty shadowMap16Bit;
 
         public SerializedProperty maxPointLightShadows;
         public SerializedProperty maxSpotLightShadows;
 
             shadowAtlasWidth = root.Find((ShadowInitParameters s) => s.shadowAtlasWidth);
             shadowAtlasHeight = root.Find((ShadowInitParameters s) => s.shadowAtlasHeight);
+            shadowMap16Bit = root.Find((ShadowInitParameters s) => s.shadowMap16Bit);
             maxPointLightShadows = root.Find((ShadowInitParameters s) => s.maxPointLightShadows);
             maxSpotLightShadows = root.Find((ShadowInitParameters s) => s.maxSpotLightShadows);
             maxDirectionalLightShadows = root.Find((ShadowInitParameters s) => s.maxDirectionalLightShadows);

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

             ++EditorGUI.indentLevel;
             EditorGUILayout.PropertyField(d.shadowAtlasWidth, _.GetContent("Atlas Width"));
             EditorGUILayout.PropertyField(d.shadowAtlasHeight, _.GetContent("Atlas Height"));
+            EditorGUILayout.PropertyField(d.shadowMap16Bit, _.GetContent("16-bit Shadow Maps"));
             --EditorGUI.indentLevel;
 
             EditorGUILayout.Space();

com.unity.render-pipelines.high-definition/HDRP/Lighting/LightLoop/LightLoop.cs

             atlasInit.baseInit.width           = (uint)shadowInit.shadowAtlasWidth;
             atlasInit.baseInit.height          = (uint)shadowInit.shadowAtlasHeight;
             atlasInit.baseInit.slices          = 1;
-            atlasInit.baseInit.shadowmapBits   = 32;
+            atlasInit.baseInit.shadowmapBits   = shadowInit.shadowMap16Bit ? 16u : 32u;
             atlasInit.baseInit.shadowmapFormat = RenderTextureFormat.Shadowmap;
             atlasInit.baseInit.samplerState    = SamplerState.Default();
             atlasInit.baseInit.comparisonSamplerState = ComparisonSamplerState.Default();
             m_ShadowMgr = new ShadowManager(shadowSettings, ref scInit, ref budgets, m_Shadowmaps);
             // set global overrides - these need to match the override specified in LightLoop/Shadow.hlsl
             bool useGlobalOverrides = true;
-            m_ShadowMgr.SetGlobalShadowOverride(GPUShadowType.Point        , ShadowAlgorithm.PCF, ShadowVariant.V2, ShadowPrecision.High, useGlobalOverrides);
-            m_ShadowMgr.SetGlobalShadowOverride(GPUShadowType.Spot         , ShadowAlgorithm.PCF, ShadowVariant.V2, ShadowPrecision.High, useGlobalOverrides);
-            m_ShadowMgr.SetGlobalShadowOverride(GPUShadowType.Directional  , ShadowAlgorithm.PCF, ShadowVariant.V3, ShadowPrecision.High, useGlobalOverrides);
+            m_ShadowMgr.SetGlobalShadowOverride(GPUShadowType.Point        , ShadowAlgorithm.PCF, ShadowVariant.V2, shadowInit.shadowMap16Bit ? ShadowPrecision.Low : ShadowPrecision.High, useGlobalOverrides);
+            m_ShadowMgr.SetGlobalShadowOverride(GPUShadowType.Spot         , ShadowAlgorithm.PCF, ShadowVariant.V2, shadowInit.shadowMap16Bit ? ShadowPrecision.Low : ShadowPrecision.High, useGlobalOverrides);
+            m_ShadowMgr.SetGlobalShadowOverride(GPUShadowType.Directional  , ShadowAlgorithm.PCF, ShadowVariant.V3, shadowInit.shadowMap16Bit ? ShadowPrecision.Low : ShadowPrecision.High, useGlobalOverrides);
 
             m_ShadowMgr.SetShadowLightTypeDelegate(HDShadowLightType);