Added Unity project files

Packages/com.vrchat.base/Editor/VRCSDK/VRCUndoPostProcessor.cs

@@ -0,0 +1,46 @@
+using UnityEditor;
+using UnityEngine;
+
+namespace VRC.SDK3.Editor
+{
+    [InitializeOnLoad]
+    internal static class VRCUndoPostProcessor
+    {
+        private const string ShaderField = "m_Shader";
+        private const string FallbackTag = "VRCFallback";
+
+        static VRCUndoPostProcessor()
+        {
+            Undo.postprocessModifications += HandleUndoPostProcess;
+        }
+
+        private static UndoPropertyModification[] HandleUndoPostProcess(UndoPropertyModification[] modifications)
+        {
+            foreach (UndoPropertyModification modification in modifications)
+            {
+                PropertyModification propertyMod = modification.currentValue;
+                if (propertyMod.propertyPath == ShaderField)
+                {
+                    Shader oldShader = modification.previousValue.objectReference as Shader;
+                    Shader newShader = propertyMod.objectReference as Shader;
+
+                    // Is the shader changing?
+                    if (oldShader != newShader)
+                    {
+                        Material mat = propertyMod.target as Material;
+                        if (mat == null)
+                        {
+                            continue;
+                        }
+
+                        // Clear VRCFallback as the shader changes. This attempts to avoid override tags set by community
+                        // tooling "bleeding over" into shaders they don't control when the user swaps over directly.
+                        mat.SetOverrideTag(FallbackTag, string.Empty);
+                    }
+                }
+            }
+
+            return modifications;
+        }
+    }
+}