Improve the SSS profile GUI

Assets/ScriptableRenderPipeline/HDRenderPipeline/SceneSettings/SubsurfaceScatteringParameters.cs

 using System;
+using UnityEngine.Rendering;
 #if UNITY_EDITOR
     using UnityEditor;
 #endif
         public SubsurfaceScatteringProfile()
         {
             stdDev1             = new Color(0.3f, 0.3f, 0.3f, 0.0f);
-            stdDev2             = new Color(1.0f, 1.0f, 1.0f, 0.0f);
+            stdDev2             = new Color(0.6f, 0.6f, 0.6f, 0.0f);
             lerpWeight          = 0.5f;
             enableTransmittance = false;
             thicknessScale      = 3.0f;
             get { return m_FilterKernels; }
         }
 
-        // --- Private Methods ---
-
-        void OnValidate()
+        public void OnValidate()
         {
             if (m_Profiles.Length > maxNumProfiles)
             {
             public readonly GUIContent profileThicknessScale = new GUIContent("Thickness scale",       "Linearly scales the object thickness which affects the amount of transmitted lighting.");
         }
 
-        private static Styles s_Styles;
+        private static Styles      s_Styles;
+        private Material           m_ProfileMaterial;
+        private RenderTexture[]    m_ProfileImages;
 
         // --- Public Methods ---
 
 
         void OnEnable()
         {
-            m_Profiles    = serializedObject.FindProperty("m_Profiles");
-            m_NumProfiles = m_Profiles.FindPropertyRelative("Array.size");
+            m_Profiles        = serializedObject.FindProperty("m_Profiles");
+            m_NumProfiles     = m_Profiles.FindPropertyRelative("Array.size");
+            m_ProfileMaterial = Utilities.CreateEngineMaterial("Hidden/HDRenderPipeline/DrawGaussianProfile");
+            m_ProfileImages   = new RenderTexture[SubsurfaceScatteringParameters.maxNumProfiles];
+
+            for (int i = 0; i < SubsurfaceScatteringParameters.maxNumProfiles; i++)
+            {
+                m_ProfileImages[i] = new RenderTexture(256, 256, 0, RenderTextureFormat.DefaultHDR);
+            }
         }
 
         public override void OnInspectorGUI()
             EditorGUI.BeginChangeCheck();
+
+            // Validate the data before displaying it.
+            ((SubsurfaceScatteringParameters)serializedObject.targetObject).OnValidate();
 
             EditorGUILayout.LabelField(styles.category);
             EditorGUILayout.PropertyField(m_NumProfiles, styles.numProfiles);
                         EditorGUILayout.PropertyField(profileLerpWeight,     styles.profileLerpWeight);
                         EditorGUILayout.PropertyField(profileTransmittance,  styles.profileTransmittance);
                         EditorGUILayout.PropertyField(profileThicknessScale, styles.profileThicknessScale);
+
+                        EditorGUILayout.Space();
+                        using (new EditorGUILayout.HorizontalScope())
+                        {
+                            // Draw the profile.
+                            m_ProfileMaterial.SetColor("_StdDev1",    profileStdDev1.colorValue);
+                            m_ProfileMaterial.SetColor("_StdDev2",    profileStdDev2.colorValue);
+                            m_ProfileMaterial.SetFloat("_LerpWeight", profileLerpWeight.floatValue);
+                            Graphics.Blit(null, m_ProfileImages[i], m_ProfileMaterial);
+                            
+                            // Reset the active RT.
+                            RenderTexture.active = null;
+
+                            GUILayout.FlexibleSpace();
+                            Rect r = GUILayoutUtility.GetRect(256, 256);
+                            GUILayout.FlexibleSpace();
+                            EditorGUI.DrawPreviewTexture(r, m_ProfileImages[i]);
+                        }
+                        EditorGUILayout.Space();
+
 
                         EditorGUI.indentLevel--;
                     }

Assets/ScriptableRenderPipeline/HDRenderPipeline/SceneSettings/Resources/DrawGaussianProfile.shader

+Shader "Hidden/HDRenderPipeline/DrawGaussianProfile"
+{
+    Properties
+    {
+        [HideInInspector] _StdDev1("", Color) = (0, 0, 0)
+        [HideInInspector] _StdDev2("", Color) = (0, 0, 0)
+        [HideInInspector] _LerpWeight("", Float) = 0
+    }
+
+    SubShader
+    {
+        Pass
+        {
+            Cull   Off
+            ZTest  Off
+            ZWrite Off
+            Blend  Off
+
+            HLSLPROGRAM
+            #pragma target 4.5
+            #pragma only_renderers d3d11 ps4 metal // TEMP: until we go further in dev
+
+            #pragma vertex Vert
+            #pragma fragment Frag
+
+            //-------------------------------------------------------------------------------------
+            // Include
+            //-------------------------------------------------------------------------------------
+
+            #include "ShaderLibrary/Common.hlsl"
+            #include "ShaderLibrary/Color.hlsl"
+            #include "HDRenderPipeline/ShaderVariables.hlsl"
+
+            //-------------------------------------------------------------------------------------
+            // Inputs & outputs
+            //-------------------------------------------------------------------------------------
+
+            float4 _StdDev1, _StdDev2; float _LerpWeight; // See 'SubsurfaceScatteringParameters'
+
+            //-------------------------------------------------------------------------------------
+            // Implementation
+            //-------------------------------------------------------------------------------------
+
+            struct Attributes
+            {
+                float3 vertex   : POSITION;
+                float2 texcoord : TEXCOORD0;
+            };
+
+            struct Varyings
+            {
+                float4 vertex   : SV_POSITION;
+                float2 texcoord : TEXCOORD0;
+            };
+
+            Varyings Vert(Attributes input)
+            {
+                Varyings output;
+                output.vertex = TransformWorldToHClip(input.vertex);
+                output.texcoord = input.texcoord.xy;
+                return output;
+            }
+
+            float4 Frag(Varyings input) : SV_Target
+            {
+                float  dist = length(2 * input.texcoord - 1);
+
+                float3 var1 = _StdDev1.rgb * _StdDev1.rgb;
+                float3 var2 = _StdDev2.rgb * _StdDev2.rgb;
+
+                // Evaluate the linear combination of two 2D Gaussians instead of
+                // product of a linear combination of two normalized 1D Gaussians
+                // since we do not want to bother artists with the lack of radial symmetry.
+
+                float3 magnitude = lerp(exp(-dist * dist / (2 * var1)) / (TWO_PI * var1),
+                                        exp(-dist * dist / (2 * var2)) / (TWO_PI * var2), _LerpWeight);
+
+                return float4(magnitude, 1);
+            }
+            ENDHLSL
+        }
+    }
+    Fallback Off
+}

Assets/ScriptableRenderPipeline/HDRenderPipeline/SceneSettings/Resources/DrawGaussianProfile.shader.meta

+fileFormatVersion: 2
+guid: 2e8a76823cb2af944b4b45169f2649f9
+timeCreated: 1487181006
+licenseType: Pro
+ShaderImporter:
+  defaultTextures: []
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: