Unity --- 在原目录中，将选中的Texture剥离为rgb和alpha

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEditor;
 using System;
 using UObject = UnityEngine.Object;
 using System.IO;

 public class lgs
 {
     [MenuItem("Assets/AlphaSpliter ")]
     static void AlphaSpliter()
     {
         UObject[] objs = Selection.objects;
         for (int i = ; i < objs.Length; i++)
         {
             Texture tex = objs[i] as Texture;
             CreateRGBTexture(tex);
             CreateAlphaTexture(tex as Texture2D);
         }
     }

     static void CreateAlphaTexture(Texture2D src)
     {
         if (null == src)
             throw new ArgumentNullException("src");

         //create alpha texture
         var srcPixels = src.GetPixels();
         var targetPixels = new Color[srcPixels.Length];
         for (int i = , iMax = srcPixels.Length; i < iMax; ++i)
         {
             float r = srcPixels[i].a;
             targetPixels[i] = new Color(r, r, r);
         }

         Texture2D alphaTex = new Texture2D(src.width, src.height, TextureFormat.ARGB32, false);
         alphaTex.SetPixels(targetPixels);
         alphaTex.Apply();

         //save alpha texture
         string srcPath = AssetDatabase.GetAssetPath(src);
         string ext = Path.GetExtension(srcPath);
         string newPath = string.Format("{0}{1}{2}", srcPath.Substring(, srcPath.Length - ext.Length), "_alpha", ext);
         string fullPath = GetFullPath(newPath);
         var bytes = alphaTex.EncodeToPNG();
         File.WriteAllBytes(fullPath, bytes);

         AssetDatabase.SaveAssets();
         AssetDatabase.Refresh();

         int size = Mathf.Max(src.width, src.height, );
         Setting(newPath, size, TextureImporterFormat.ETC_RGB4, TextureImporterFormat.PVRTC_RGB4);
     }

     static void CreateRGBTexture(Texture src)
     {
         if (null == src)
             throw new ArgumentNullException("src");

         string srcPath = AssetDatabase.GetAssetPath(src);
         string ext = Path.GetExtension(srcPath);
         string newPath = string.Format("{0}{1}{2}", srcPath.Substring(, srcPath.Length - ext.Length), "_rgb", ext);

         AssetDatabase.DeleteAsset(newPath);
         AssetDatabase.CopyAsset(srcPath, newPath);
         AssetDatabase.ImportAsset(newPath);

         int size = Mathf.Max(src.width, src.height, );
         Setting(newPath, size, TextureImporterFormat.ETC_RGB4, TextureImporterFormat.PVRTC_RGB4);
     }

     static void Setting(string assetPath, int maxSize, TextureImporterFormat androidFormat, TextureImporterFormat iosFormat)
     {
         var texImporter = AssetImporter.GetAtPath(assetPath) as TextureImporter;
         {
             texImporter.npotScale = TextureImporterNPOTScale.ToNearest;
             texImporter.isReadable = false;
             texImporter.mipmapEnabled = false;
             texImporter.alphaIsTransparency = true;
             texImporter.wrapMode = TextureWrapMode.Clamp;
             texImporter.filterMode = FilterMode.Bilinear;
             texImporter.anisoLevel = ;    //纹理的各向异性滤波水平
             texImporter.SetPlatformTextureSettings("Android", maxSize, androidFormat);
             texImporter.SetPlatformTextureSettings("iPhone", maxSize, iosFormat);
             texImporter.SetPlatformTextureSettings("Standalone", maxSize, TextureImporterFormat.ARGB32);
         }

         AssetDatabase.ImportAsset(assetPath);
         AssetDatabase.SaveAssets();
     }

     /// <summary>
     /// asset path 转 full path
     /// </summary>
     public static string GetFullPath(string assetPath)
     {
         if (string.IsNullOrEmpty(assetPath))
             return "";

         string p = Application.dataPath + assetPath.Substring();
         return p.Replace("\\", "/");
     }

     /// <summary>
     /// full path 转 asset path
     /// </summary>
     public static string GetAssetPath(string fullPath)
     {
         if (string.IsNullOrEmpty(fullPath))
             return "";

         fullPath = fullPath.Replace("\\", "/");
         return fullPath.StartsWith("Assets/") ?
             fullPath :
             "Assets" + fullPath.Substring(Application.dataPath.Length);
     }
 }