various fix + backport change of WRITE_NORMAL_BUFFER on all shader + add shader preprocessor

com.unity.render-pipelines.high-definition/HDRP/Editor/Material/Lit/LitShaderPreprocessor.cs

 using UnityEditor.Build;
 using UnityEditor.Rendering;
 using UnityEngine;
+using UnityEngine.Rendering;
 using UnityEngine.Experimental.Rendering.HDPipeline;
 
 namespace UnityEditor.Experimental.Rendering.HDPipeline
+        protected ShaderKeyword m_WriteNormalBuffer;
+
+        LitShaderPreprocessor()
+        {
+            m_WriteNormalBuffer = new ShaderKeyword("WRITE_NORMAL_BUFFER");
+        }
+
         bool LitShaderStripper(HDRenderPipelineAsset hdrpAsset, Shader shader, ShaderSnippetData snippet, ShaderCompilerData inputData)
         {
             if (CommonShaderStripper(hdrpAsset, shader, snippet, inputData))
             bool isForwardPass = snippet.passName == "Forward";
+            bool isDepthOnlyPass = snippet.passName == "DepthOnly";
             bool isTransparentForwardPass = snippet.passName == "TransparentDepthPostpass" || snippet.passName == "TransparentBackface" || snippet.passName == "TransparentDepthPrepass";
 
             // When using forward only, we never need GBuffer pass (only Forward)
                 // When we are in deferred (i.e !hdrpAsset.renderPipelineSettings.supportOnlyForward), we only support tile lighting
                 if (!hdrpAsset.renderPipelineSettings.supportOnlyForward && inputData.shaderKeywordSet.IsEnabled(m_ClusterLighting))
                     return true;
+
+                if (isDepthOnlyPass)
+                {
+                    // When we are full forward, we don't have depth prepass without writeNormalBuffer
+                    if (hdrpAsset.renderPipelineSettings.supportOnlyForward && !inputData.shaderKeywordSet.IsEnabled(m_WriteNormalBuffer))
+                        return true;
+
+                    // When we are in deferred we don't have depth prepass with writeNormalBuffer
+                    if (!hdrpAsset.renderPipelineSettings.supportOnlyForward && inputData.shaderKeywordSet.IsEnabled(m_WriteNormalBuffer))
+                        return true;
+                }
 
                 if (!hdrpAsset.renderPipelineSettings.supportOnlyForward)
                 {

com.unity.render-pipelines.high-definition/HDRP/Material/LayeredLit/LayeredLit.shader

 
             ZWrite On
 
-            ColorMask 0
+            HLSLPROGRAM
-            HLSLPROGRAM
+            // In deferred, depth only pass don't output anything.
+            // In forward it output the normal buffer
+            #pragma multi_compile _ WRITE_NORMAL_BUFFER
+
+            #ifdef WRITE_NORMAL_BUFFER // If enabled we need all regular interpolator
+            #include "../Lit/ShaderPass/LitSharePass.hlsl"
+            #else
+            #endif
+
             #include "LayeredLitData.hlsl"
             #include "../../ShaderPass/ShaderPassDepthOnly.hlsl"
 

com.unity.render-pipelines.high-definition/HDRP/Material/LayeredLit/LayeredLitTessellation.shader

 
             ZWrite On
 
-            ColorMask 0
-
+
+           // In deferred, depth only pass don't output anything.
+            // In forward it output the normal buffer
+            #pragma multi_compile _ WRITE_NORMAL_BUFFER
+
+            #ifdef WRITE_NORMAL_BUFFER // If enabled we need all regular interpolator
+            #include "../Lit/ShaderPass/LitSharePass.hlsl"
+            #else
+            #endif
+
             #include "LayeredLitData.hlsl"
             #include "../../ShaderPass/ShaderPassDepthOnly.hlsl"
 

com.unity.render-pipelines.high-definition/HDRP/Material/Lit/Lit.hlsl

 #define CLEAR_COAT_IOR 1.5
 #define CLEAR_COAT_IETA (1.0 / CLEAR_COAT_IOR) // IETA is the inverse eta which is the ratio of IOR of two interface
 #define CLEAR_COAT_F0 0.04 // IORToFresnel0(CLEAR_COAT_IOR)
-#define CLEAR_COAT_ROUGHNESS 0.01
+#define CLEAR_COAT_ROUGHNESS 0.001
 #define CLEAR_COAT_PERCEPTUAL_ROUGHNESS RoughnessToPerceptualRoughness(CLEAR_COAT_ROUGHNESS)
 
 //-----------------------------------------------------------------------------

com.unity.render-pipelines.high-definition/HDRP/Material/Lit/Lit.shader

             #define SHADERPASS SHADERPASS_DEPTH_ONLY
             #include "../../ShaderVariables.hlsl"
             #include "../../Material/Material.hlsl"
+
+            #ifdef WRITE_NORMAL_BUFFER // If enabled we need all regular interpolator
+            #include "ShaderPass/LitSharePass.hlsl"
+            #else
+            #endif
+
             #include "LitData.hlsl"
             #include "../../ShaderPass/ShaderPassDepthOnly.hlsl"
 

com.unity.render-pipelines.high-definition/HDRP/Material/Lit/LitTessellation.shader

 
             ZWrite On
 
-            ColorMask 0
-
+
+            // In deferred, depth only pass don't output anything.
+            // In forward it output the normal buffer
+            #pragma multi_compile _ WRITE_NORMAL_BUFFER
+
+            #ifdef WRITE_NORMAL_BUFFER // If enabled we need all regular interpolator
+            #include "ShaderPass/LitSharePass.hlsl"
+            #else
+            #endif
+
             #include "LitData.hlsl"
             #include "../../ShaderPass/ShaderPassDepthOnly.hlsl"
 

com.unity.render-pipelines.high-definition/HDRP/Material/StackLit/StackLit.shader

             #define SHADERPASS SHADERPASS_DEPTH_ONLY
             #include "../../ShaderVariables.hlsl"
             #include "../../Material/Material.hlsl"
-            #include "ShaderPass/StackLitDepthPass.hlsl"
+            // As we enabled WRITE_NORMAL_BUFFER we need all regular interpolator
+            #include "ShaderPass/StackLitSharePass.hlsl"
             #include "StackLitData.hlsl"
             #include "../../ShaderPass/ShaderPassDepthOnly.hlsl"
 

com.unity.render-pipelines.high-definition/HDRP/RenderPipeline/HDRenderPipeline.cs

             {
                 using (new ProfilingSample(cmd, "Depth Prepass (forward)", CustomSamplerId.DepthPrepass.GetSampler()))
                 {
-                    cmd.EnableShaderKeyword("OUTPUT_NORMAL_BUFFER");
+                    cmd.EnableShaderKeyword("WRITE_NORMAL_BUFFER");
 
                     HDUtils.SetRenderTarget(cmd, hdCamera, m_NormalBufferManager.GetBuffersRTI(), m_CameraDepthStencilBuffer);
 
             {
                 using (new ProfilingSample(cmd, "Depth Prepass (deferred)", CustomSamplerId.DepthPrepass.GetSampler()))
                 {
-                    cmd.DisableShaderKeyword("OUTPUT_NORMAL_BUFFER"); // Note: This only disable the output of normal buffer for Lit shader, not the other shader that don't use multicompile
+                    cmd.DisableShaderKeyword("WRITE_NORMAL_BUFFER"); // Note: This only disable the output of normal buffer for Lit shader, not the other shader that don't use multicompile
                     
                     HDUtils.SetRenderTarget(cmd, hdCamera, m_CameraDepthStencilBuffer);
 
             {
                 using (new ProfilingSample(cmd, "Depth Prepass (deferred incomplete)", CustomSamplerId.DepthPrepass.GetSampler()))
                 {
-                    cmd.DisableShaderKeyword("OUTPUT_NORMAL_BUFFER");
+                    cmd.DisableShaderKeyword("WRITE_NORMAL_BUFFER");
 
                     HDUtils.SetRenderTarget(cmd, hdCamera, m_CameraDepthStencilBuffer);