From 8521e988172d7aab9da9aaddff7e91068fa4299d Mon Sep 17 00:00:00 2001
From: Masataka SUMI <santarh@gmail.com>
Date: Fri, 4 Nov 2022 22:52:34 +0900
Subject: [PATCH] Convert emissiveFactor's color space into gamma with Built-in
 RP Standard shader.

---
 .../Extensions/ColorConversionExtensions.cs   |  5 ++++
 .../BuiltInStandardMaterialExporter.cs        |  3 ++-
 .../Materials/GltfPbrMaterialImporter.cs      | 25 +++++++++++++------
 .../Runtime/UniGLTF/IO/MigrationFlags.cs      |  5 ++++
 4 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/Assets/UniGLTF/Runtime/Extensions/ColorConversionExtensions.cs b/Assets/UniGLTF/Runtime/Extensions/ColorConversionExtensions.cs
index 1e6daabe7..e78ab1556 100644
--- a/Assets/UniGLTF/Runtime/Extensions/ColorConversionExtensions.cs
+++ b/Assets/UniGLTF/Runtime/Extensions/ColorConversionExtensions.cs
@@ -40,6 +40,11 @@ namespace UniGLTF
             return new Color(src[0], src[1], src[2], 1f).ConvertColorSpace(srcColorSpace, dstColorSpace);
         }
 
+        public static Color ToColor3(this Vector3 src, ColorSpace srcColorSpace, ColorSpace dstColorSpace)
+        {
+            return new Color(src.x, src.y, src.z).ConvertColorSpace(srcColorSpace, dstColorSpace);
+        }
+
         private static Color ConvertColorSpace(this Color srcColor, ColorSpace srcColorSpace, ColorSpace dstColorSpace)
         {
             // Need pattern matching :(
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialIO/BuiltInRP/Export/Materials/BuiltInStandardMaterialExporter.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialIO/BuiltInRP/Export/Materials/BuiltInStandardMaterialExporter.cs
index e2f8d66df..f7b4b9c7b 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialIO/BuiltInRP/Export/Materials/BuiltInStandardMaterialExporter.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialIO/BuiltInRP/Export/Materials/BuiltInStandardMaterialExporter.cs
@@ -189,7 +189,8 @@ namespace UniGLTF
                     color /= maxColorComponent;
                     UniGLTF.glTF_KHR_materials_emissive_strength.Serialize(ref dst.extensions, maxColorComponent);
                 }
-                dst.emissiveFactor = color.ToFloat3(ColorSpace.Linear, ColorSpace.Linear);
+                // NOTE: Built-in RP Standard shader's emission color is in gamma color space.
+                dst.emissiveFactor = color.ToFloat3(ColorSpace.sRGB, ColorSpace.Linear);
             }
 
             if (src.HasProperty(EmissionTexturePropertyName))
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialIO/BuiltInRP/Import/Materials/GltfPbrMaterialImporter.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialIO/BuiltInRP/Import/Materials/GltfPbrMaterialImporter.cs
index cb5c8767e..a24b96048 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialIO/BuiltInRP/Import/Materials/GltfPbrMaterialImporter.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/MaterialIO/BuiltInRP/Import/Materials/GltfPbrMaterialImporter.cs
@@ -143,19 +143,30 @@ namespace UniGLTF
 
                 if (src.emissiveFactor != null && src.emissiveFactor.Length == 3)
                 {
-                    var emissiveFactor = src.emissiveFactor.ToColor3(ColorSpace.Linear, ColorSpace.Linear);
-                    if (UniGLTF.glTF_KHR_materials_emissive_strength.TryGet(src.extensions, out UniGLTF.glTF_KHR_materials_emissive_strength emissiveStrength))
+                    var emissiveFactor = new Vector3(src.emissiveFactor[0], src.emissiveFactor[1], src.emissiveFactor[2]);
+                    if (glTF_KHR_materials_emissive_strength.TryGet(src.extensions, out var emissiveStrength))
                     {
                         emissiveFactor *= emissiveStrength.emissiveStrength;
                     }
-                    else if (UniGLTF.Extensions.VRMC_materials_hdr_emissiveMultiplier.GltfDeserializer.TryGet(src.extensions,
-                        out UniGLTF.Extensions.VRMC_materials_hdr_emissiveMultiplier.
-                            VRMC_materials_hdr_emissiveMultiplier ex))
+                    else if (Extensions.VRMC_materials_hdr_emissiveMultiplier.GltfDeserializer.TryGet(src.extensions, out var ex))
                     {
-                        emissiveFactor *= ex.EmissiveMultiplier.Value;
+                        if (ex.EmissiveMultiplier != null)
+                        {
+                            emissiveFactor *= ex.EmissiveMultiplier.Value;
+                        }
+                    }
+
+                    if (data.MigrationFlags.IsEmissiveFactorGamma)
+                    {
+                        // NOTE: Do nothing.
+                        colors.Add("_EmissionColor", emissiveFactor.ToColor3(ColorSpace.sRGB, ColorSpace.sRGB));
+                    }
+                    else
+                    {
+                        // NOTE: Built-in RP Standard shader's emission color is in gamma color space.
+                        colors.Add("_EmissionColor", emissiveFactor.ToColor3(ColorSpace.Linear, ColorSpace.sRGB));
                     }
 
-                    colors.Add("_EmissionColor", emissiveFactor);
                 }
 
                 if (src.emissiveTexture != null && src.emissiveTexture.index != -1)
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/MigrationFlags.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/MigrationFlags.cs
index 1dfa79e80..0da201b7d 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/MigrationFlags.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/MigrationFlags.cs
@@ -6,5 +6,10 @@
         /// Before UniGLTF v0.69, roughness value in the texture was invalid squared value.
         /// </summary>
         public bool IsRoughnessTextureValueSquared { get; set; } = false;
+
+        /// <summary>
+        /// Built-in RP Standard shader's emission color is exported in gamma color space until UniGLTF v0.106.0.
+        /// </summary>
+        public bool IsEmissiveFactorGamma { get; set; } = false;
     }
 }
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