Spike custom vertex attribute handling

Penumbra/Import/Models/Export/MeshExporter.cs

@@ -373,7 +373,7 @@ public class MeshExporter
 
         return materialUsages switch
         {
-            (2, true)  => typeof(VertexColor1Texture2),
+            (2, true)  => typeof(VertexTexture2ColorFfxiv),
             (2, false) => typeof(VertexTexture2),
             (1, true)  => typeof(VertexColor1Texture1),
             (1, false) => typeof(VertexTexture1),
@@ -413,13 +413,13 @@ public class MeshExporter
             );
         }
 
-        if (_materialType == typeof(VertexColor1Texture2))
+        if (_materialType == typeof(VertexTexture2ColorFfxiv))
         {
             var uv = ToVector4(attributes[MdlFile.VertexUsage.UV]);
-            return new VertexColor1Texture2(
+            return new VertexTexture2ColorFfxiv(
-                ToVector4(attributes[MdlFile.VertexUsage.Color]),
                 new Vector2(uv.X, uv.Y),
-                new Vector2(uv.Z, uv.W)
+                new Vector2(uv.Z, uv.W),
+                ToVector4(attributes[MdlFile.VertexUsage.Color])
             );
         }
 

Penumbra/Import/Models/Export/VertexFragment.cs

@@ -0,0 +1,92 @@
+using SharpGLTF.Geometry.VertexTypes;
+using SharpGLTF.Schema2;
+
+namespace Penumbra.Import.Models.Export;
+
+public struct VertexTexture2ColorFfxiv : IVertexCustom
+{
+    public const string FFXIV_COLOR = "_FFXIV_COLOR";
+
+    [VertexAttribute("TEXCOORD_0")]
+    public Vector2 TexCoord0;
+
+    [VertexAttribute("TEXCOORD_1")]
+    public Vector2 TexCoord1;
+
+    [VertexAttribute(FFXIV_COLOR, EncodingType.UNSIGNED_BYTE, false)]
+    public Vector4 FfxivColor;
+
+    public int MaxColors => 0;
+
+    public int MaxTextCoords => 2;
+
+    private static readonly string[] CustomNames = [FFXIV_COLOR];
+    public IEnumerable<string> CustomAttributes => CustomNames;
+
+    public VertexTexture2ColorFfxiv(Vector2 texCoord0, Vector2 texCoord1, Vector4 ffxivColor)
+    {
+        TexCoord0 = texCoord0;
+        TexCoord1 = texCoord1;
+        FfxivColor = ffxivColor;
+    }
+
+    public void Add(in VertexMaterialDelta delta)
+    {
+        TexCoord0 += delta.TexCoord0Delta;
+        TexCoord1 += delta.TexCoord1Delta;
+    }
+
+    public VertexMaterialDelta Subtract(IVertexMaterial baseValue)
+    {
+        return new VertexMaterialDelta(Vector4.Zero, Vector4.Zero, TexCoord0 - baseValue.GetTexCoord(0), TexCoord1 - baseValue.GetTexCoord(1));
+    }
+
+    public Vector2 GetTexCoord(int index)
+        => index switch
+        {
+            0 => TexCoord0,
+            1 => TexCoord1,
+            _ => throw new ArgumentOutOfRangeException(nameof(index)),
+        };
+
+    public void SetTexCoord(int setIndex, Vector2 coord)
+    {
+        if (setIndex == 0) TexCoord0 = coord;
+        if (setIndex == 1) TexCoord1 = coord;
+        if (setIndex >= 2) throw new ArgumentOutOfRangeException(nameof(setIndex));
+    }
+
+    public bool TryGetCustomAttribute(string attributeName, out object? value)
+    {
+        switch (attributeName)
+        {
+            case FFXIV_COLOR:
+                value = FfxivColor;
+                return true;
+
+            default:
+                value = null;
+                return false;
+        }
+    }
+
+    public void SetCustomAttribute(string attributeName, object value)
+    {
+        if (attributeName == FFXIV_COLOR && value is Vector4 valueVector4)
+            FfxivColor = valueVector4;
+    }
+
+    public Vector4 GetColor(int index)
+        => throw new ArgumentOutOfRangeException(nameof(index));
+
+    public void SetColor(int setIndex, Vector4 color)
+    {
+    }
+
+    public void Validate()
+    {
+        var components = new[] { FfxivColor.X, FfxivColor.Y, FfxivColor.Z, FfxivColor.W };
+        if (components.Any(component => component < 0 || component > 1))
+            throw new ArgumentOutOfRangeException(nameof(FfxivColor));
+    }
+}

Penumbra/Import/Models/Import/VertexAttribute.cs

@@ -395,7 +395,9 @@ public class VertexAttribute
 
     public static VertexAttribute Color(Accessors accessors)
     {
-        accessors.TryGetValue("COLOR_0", out var accessor);
+        // Try to retrieve the custom color attribute we use for export, falling back to the glTF standard name.
+        if (!accessors.TryGetValue("_FFXIV_COLOR", out var accessor))
+            accessors.TryGetValue("COLOR_0", out accessor);
 
         var element = new MdlStructs.VertexElement()
         {