Merge pull request #504 from Unity-Technologies/feature/transparentSpecularBlending

Feature/transparent specular blending

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLit.shader

         [HideInInspector] _ShowLayer1("_ShowLayer1", Float) = 0
         [HideInInspector] _ShowLayer2("_ShowLayer2", Float) = 0
         [HideInInspector] _ShowLayer3("_ShowLayer3", Float) = 0
+
+        // Transparency
+        [ToggleOff] _PreRefractionPass("PreRefractionPass", Float) = 0.0
     }
 
     HLSLINCLUDE

ScriptableRenderPipeline/HDRenderPipeline/Material/LayeredLit/LayeredLitTessellation.shader

         _TessellationShapeFactor("Tessellation shape factor", Range(0.0, 1.0)) = 0.75 // Only use with Phong
         _TessellationBackFaceCullEpsilon("Tessellation back face epsilon", Range(-1.0, 0.0)) = -0.25
         // TODO: Handle culling mode for backface culling
+
+        // Transparency
+        [ToggleOff] _PreRefractionPass("PreRefractionPass", Float) = 0.0
     }
 
     HLSLINCLUDE

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Editor/LitUI.cs

         protected MaterialProperty refractionMode = null;
         protected const string kRefractionMode = "_RefractionMode";
 
+        protected override bool showBlendModePopup
+        {
+            get { return refractionMode == null || refractionMode.floatValue == 0f; }
+        }
+
         protected void FindMaterialLayerProperties(MaterialProperty[] props)
         {
             for (int i = 0; i < m_LayerCount; ++i)
                         ++EditorGUI.indentLevel;
 
                         m_MaterialEditor.ShaderProperty(ior, Styles.refractionIORText);
+
+                        blendMode.floatValue = (float)BlendMode.Lerp;
 
                         if (mode != Lit.RefractionMode.ThinPlane)
                         {

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/Lit.shader

 
         _DistortionVectorMap("DistortionVectorMap", 2D) = "black" {}
         [ToggleOff] _DistortionEnable("Enable Distortion", Float) = 0.0
-        [ToggleOff] _DistortionOnly("Distortion Only", Float) = 0.0
         [ToggleOff] _DistortionDepthTest("Distortion Depth Test Enable", Float) = 0.0
         [Enum(Add, 0, Multiply, 1)] _DistortionBlendMode("Distortion Blend Mode", Int) = 0
         [HideInInspector] _DistortionSrcBlend("Distortion Blend Src", Int) = 0

ScriptableRenderPipeline/HDRenderPipeline/Material/Unlit/Editor/BaseUnlitUI.cs

         // See comment in LitProperties.hlsl
         const string kEmissionColor = "_EmissionColor";
 
+        bool m_ShowBlendModePopup = true;
+        protected virtual bool showBlendModePopup { get { return m_ShowBlendModePopup; } }
+
         // The following set of functions are call by the ShaderGraph
         // It will allow to display our common parameters + setup keyword correctly for them
         protected abstract void FindMaterialProperties(MaterialProperty[] props);
             SurfaceTypePopup();
             if ((SurfaceType)surfaceType.floatValue == SurfaceType.Transparent)
             {
-                BlendModePopup();
+                if (showBlendModePopup)
+                    BlendModePopup();
 
                 m_MaterialEditor.ShaderProperty(enableFog, StylesBaseUnlit.enableFogText);
 
                 {
                     EditorGUI.indentLevel++;
                     m_MaterialEditor.ShaderProperty(distortionBlendMode, StylesBaseUnlit.distortionBlendModeText);
-                    m_MaterialEditor.ShaderProperty(distortionOnly, StylesBaseUnlit.distortionOnlyText);
+                    if (distortionOnly != null)
+                        m_MaterialEditor.ShaderProperty(distortionOnly, StylesBaseUnlit.distortionOnlyText);
                     m_MaterialEditor.ShaderProperty(distortionDepthTest, StylesBaseUnlit.distortionDepthTestText);
 
                     EditorGUI.indentLevel++;

ScriptableRenderPipeline/HDRenderPipeline/ShaderPass/ShaderPassForward.hlsl

 
 #endif // TESSELLATION_ON
 
+float4 BlendDiffuseSpecular(float3 diffuse, float3 specular, float opacity)
+{
+    return float4(diffuse + specular, opacity);
+}
+
+float4 BlendDiffuseWithConsistentSpecular(float3 diffuse, float3 specular, float opacity)
+{
+#ifdef _BLENDMODE_ALPHA
+    return float4(diffuse + (specular / max(opacity, 0.01)), opacity);
+#elif defined(_BLENDMODE_ADD) || defined(_BLENDMODE_PRE_MULTIPLY)
+    return float4(diffuse * opacity + specular, opacity);
+#else
+    return BlendDiffuseSpecular(diffuse, specular, opacity);
+#endif
+}
+
 void Frag(PackedVaryingsToPS packedInput,
           out float4 outColor : SV_Target0
       #ifdef _DEPTHOFFSET_ON
     float3 bakeDiffuseLighting = GetBakedDiffuseLigthing(surfaceData, builtinData, bsdfData, preLightData);
     LightLoop(V, posInput, preLightData, bsdfData, bakeDiffuseLighting, featureFlags, diffuseLighting, specularLighting);
 
-#ifdef _BLENDMODE_ALPHA
-    outColor = float4(diffuseLighting + (specularLighting / max(builtinData.opacity, 0.01)), builtinData.opacity);
-#else
-    outColor = float4(diffuseLighting + specularLighting, builtinData.opacity);
-#endif
-    outColor = EvaluateAtmosphericScattering(posInput, outColor);
-    }
+    outColor = BlendDiffuseWithConsistentSpecular(diffuseLighting, specularLighting, builtinData.opacity);
+}
 
 #ifdef _DEPTHOFFSET_ON
     outputDepth = posInput.depthRaw;