texture stitcher (literally psd layers but im lazy)

TextureStitcher/TextureStitcher.cs

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+using UnityEditor;
+using UnityEngine;
+using System.IO;
+
+namespace gay.lilyy.TextureStitcher
+{
+  [CreateAssetMenu(fileName = "TextureStitcherSettings", menuName = "Texture Stitcher/Settings")]
+  public class TextureStitcherSettings : ScriptableObject
+  {
+    public Texture2D[] textures;
+    public string savePath = "Assets/StitchedTexture.png";
+  }
+
+  [CustomEditor(typeof(TextureStitcherSettings))]
+  public class TextureStitcherEditor : Editor
+  {
+    private SerializedProperty texturesProp;
+    private SerializedProperty savePathProp;
+
+    private void OnEnable()
+    {
+      texturesProp = serializedObject.FindProperty("textures");
+      savePathProp = serializedObject.FindProperty("savePath");
+    }
+
+    public override void OnInspectorGUI()
+    {
+      serializedObject.Update();
+
+      EditorGUILayout.LabelField("Texture Layers (Top → Bottom)", EditorStyles.boldLabel);
+      EditorGUILayout.PropertyField(savePathProp);
+
+      DrawReversedArray(texturesProp);
+
+      GUILayout.Space(10);
+
+      if (GUILayout.Button("Generate Stitched Texture"))
+        GenerateStitchedTexture();
+
+      serializedObject.ApplyModifiedProperties();
+    }
+
+    private void DrawReversedArray(SerializedProperty array)
+    {
+      if (!array.isArray)
+        return;
+
+      // Draw size field (normal Unity behavior)
+      EditorGUILayout.PropertyField(array.FindPropertyRelative("Array.size"));
+
+      // Reverse array in-place
+      int count = array.arraySize;
+      for (int i = 0; i < count / 2; i++)
+        array.MoveArrayElement(i, count - 1 - i);
+
+      // Draw array normally
+      EditorGUILayout.PropertyField(array, GUIContent.none, true);
+
+      // Restore original order
+      for (int i = 0; i < count / 2; i++)
+        array.MoveArrayElement(i, count - 1 - i);
+    }
+
+    private void GenerateStitchedTexture()
+    {
+      TextureStitcherSettings settings = (TextureStitcherSettings)target;
+      GenerateStitchedTexture(settings);
+    }
+
+    internal static void GenerateStitchedTexture(TextureStitcherSettings settings)
+    {
+      int width = 0;
+      int height = 0;
+
+      foreach (var tex in settings.textures)
+      {
+        if (!tex) continue;
+        width = Mathf.Max(width, tex.width);
+        height = Mathf.Max(height, tex.height);
+      }
+
+      Texture2D output = new Texture2D(width, height, TextureFormat.RGBA32, false);
+      Color[] pixels = new Color[width * height];
+      for (int i = 0; i < pixels.Length; i++) pixels[i] = Color.clear;
+
+      output.SetPixels(pixels);
+
+      // Bottom → top
+      for (int i = 0; i < settings.textures.Length; i++)
+      {
+        var tex = settings.textures[i];
+        if (!tex) continue;
+
+        Texture2D resized = Resize(tex, width, height);
+        Color[] src = resized.GetPixels();
+        Color[] dst = output.GetPixels();
+
+        for (int p = 0; p < dst.Length; p++)
+        {
+          Color s = src[p];
+          dst[p] = Color.Lerp(dst[p], s, s.a);
+        }
+
+        output.SetPixels(dst);
+      }
+
+      output.Apply();
+      File.WriteAllBytes(settings.savePath, output.EncodeToPNG());
+      AssetDatabase.Refresh();
+
+      Debug.Log("Stitched texture saved to " + settings.savePath);
+    }
+
+    private static Texture2D Resize(Texture2D src, int width, int height)
+    {
+      RenderTexture rt = RenderTexture.GetTemporary(width, height, 0);
+      Graphics.Blit(src, rt);
+
+      RenderTexture.active = rt;
+      Texture2D result = new Texture2D(width, height, TextureFormat.RGBA32, false);
+      result.ReadPixels(new Rect(0, 0, width, height), 0, 0);
+      result.Apply();
+
+      RenderTexture.active = null;
+      RenderTexture.ReleaseTemporary(rt);
+      return result;
+    }
+  }
+}