refactor: fix package structure

Runtime/ModifiedMaterial.cs

@@ -0,0 +1,72 @@
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace Coffee.UIParticleExtensions
+{
+    internal class ModifiedMaterial
+    {
+        private static readonly List<MatEntry> s_Entries = new List<MatEntry>();
+
+        public static Material Add(Material baseMat, Texture texture, int id, int props)
+        {
+            MatEntry e;
+            for (var i = 0; i < s_Entries.Count; i++)
+            {
+                e = s_Entries[i];
+                if (e.baseMat != baseMat || e.texture != texture || e.id != id || e.props != props) continue;
+                ++e.count;
+                return e.customMat;
+            }
+
+            e = new MatEntry
+            {
+                count = 1,
+                baseMat = baseMat,
+                texture = texture,
+                id = id,
+                props = props,
+                customMat = new Material(baseMat)
+                {
+                    name = $"{baseMat.name}_{id}",
+                    hideFlags = HideFlags.DontSave | HideFlags.NotEditable,
+                    mainTexture = texture ? texture : null
+                }
+            };
+            s_Entries.Add(e);
+            //Debug.LogFormat(">>>> ModifiedMaterial.Add -> count = count:{0}, mat:{1}, tex:{2}, id:{3}", s_Entries.Count, baseMat, texture, id);
+            return e.customMat;
+        }
+
+        public static void Remove(Material customMat)
+        {
+            if (!customMat) return;
+
+            for (var i = 0; i < s_Entries.Count; ++i)
+            {
+                var e = s_Entries[i];
+                if (e.customMat != customMat) continue;
+                if (--e.count == 0)
+                {
+                    //Debug.LogFormat(">>>> ModifiedMaterial.Remove -> count:{0}, mat:{1}, tex:{2}, id:{3}", s_Entries.Count - 1, e.customMat, e.texture, e.id);
+                    Misc.DestroyImmediate(e.customMat);
+                    e.customMat = null;
+                    e.baseMat = null;
+                    e.texture = null;
+                    s_Entries.RemoveAt(i);
+                }
+
+                break;
+            }
+        }
+
+        private class MatEntry
+        {
+            public Material baseMat;
+            public int count;
+            public Material customMat;
+            public int id;
+            public int props;
+            public Texture texture;
+        }
+    }
+}