如題一個編輯器小工具，主要在於Editor介面的使用和判斷一張圖片有無alpha通道，下面直接上程式碼：

  #region atlas deal

    public static int CompressQuality = 50;

    public static float halveRate = 0.5f;

    [MenuItem("Tools/HalveAtlas")]
    public static void HalveAtlas()
    {
        UnityEngine.Object[] objects = Selection.GetFiltered(typeof
 
(UnityEngine.Object), SelectionMode.Assets); //獲取選擇資料夾
        for (int i = 0; i < objects.Length; i++)
        {
            string dirPath = AssetDatabase.GetAssetPath(objects[i]).Replace("\\", "/");
            if (!Directory.Exists(dirPath))
            {
                EditorUtility.DisplayDialog("錯誤"
 
, "選擇正確資料夾！", "好的");
                continue;
            }
            HalveSprite(dirPath);
        }
    }

    private static void HalveSprite(string dirPath)
    {
        string[] files = Directory.GetFiles(dirPath, "*.*", SearchOption.AllDirectories);
        for (int i = 0; i < files.Length; i++)
        {
            string
 
 filePath = files[i];
            filePath = filePath.Replace("\\", "/");

            if (filePath.EndsWith(".png") || filePath.EndsWith(".jpg"))
            {
            //篩選出png和jpg圖片
                EditorUtility.DisplayProgressBar("處理中>>>", filePath, (float)i / (float)files.Length);

                TextureImporter textureImporter = AssetImporter.GetAtPath(filePath) as TextureImporter;
                if (textureImporter == null)
                    return;
                //判斷圖片有無alpha通道，有預設格式設定成：RGBA16；無預設格式設定成：RGB16
                textureImporter.textureFormat = TextureImporterFormat.AutomaticTruecolor;
                AssetDatabase.ImportAsset(filePath);

                Texture2D texture = AssetDatabase.LoadAssetAtPath<Texture2D>(filePath);
                int textureSize = Math.Max(texture.height, texture.width);

                TextureImporterFormat defaultTextureFormat = TextureImporterFormat.RGB16;
                if (texture.format == TextureFormat.RGB24)
                {
                    //no alpha
                    defaultTextureFormat = TextureImporterFormat.RGB16;
                }
                else
                {
                    defaultTextureFormat = TextureImporterFormat.RGBA16;
                }

                TextureImporterSettings settings = new TextureImporterSettings();
                textureImporter.ReadTextureSettings(settings);

                textureImporter.textureType = TextureImporterType.Advanced;
                int defaultMaxTextureSize = settings.maxTextureSize;
                defaultMaxTextureSize = Math.Min(textureSize, defaultMaxTextureSize);
                defaultMaxTextureSize = (int)(defaultMaxTextureSize * halveRate);
                settings.textureFormat = defaultTextureFormat;
                settings.maxTextureSize = GetValidSize(defaultMaxTextureSize);

                int androidMaxTextureSize = 0;
                TextureImporterFormat androidTextureFormat = UnityEditor.TextureImporterFormat.ETC_RGB4;
                bool isAndroidOverWrite = textureImporter.GetPlatformTextureSettings("Android", out androidMaxTextureSize, out androidTextureFormat);
                if (true == isAndroidOverWrite)
                {
                    androidMaxTextureSize = Math.Min(textureSize, androidMaxTextureSize);
                    androidMaxTextureSize = (int)(androidMaxTextureSize * halveRate);
                    textureImporter.SetPlatformTextureSettings("Android", GetValidSize(androidMaxTextureSize), androidTextureFormat, CompressQuality);
                }

                int iphoneMaxTextureSize = 0;
                TextureImporterFormat iphoneTextureFormat = UnityEditor.TextureImporterFormat.PVRTC_RGBA4;
                bool isIphoneOverWrite = textureImporter.GetPlatformTextureSettings("iPhone", out iphoneMaxTextureSize, out iphoneTextureFormat);
                if (true == isIphoneOverWrite)
                {
                    iphoneMaxTextureSize = Math.Min(textureSize, iphoneMaxTextureSize);
                    iphoneMaxTextureSize = (int)(iphoneMaxTextureSize * halveRate);
                    textureImporter.SetPlatformTextureSettings("iPhone", GetValidSize(iphoneMaxTextureSize), iphoneTextureFormat, CompressQuality);
                }

                textureImporter.SetTextureSettings(settings);
                AssetDatabase.SaveAssets();
                DoAssetReimport(filePath, ImportAssetOptions.ForceUpdate | ImportAssetOptions.ForceSynchronousImport);
            }
        }

        EditorUtility.ClearProgressBar();
        EditorUtility.DisplayDialog("成功", "處理完成！", "好的");
    }

    private static int GetValidSize(int size)
    {
        int result = 0;
        if (size <= 48)
        {
            result = 32;
        }
        else if (size <= 96)
        {
            result = 64;
        }
        else if (size <= 192)
        {
            result = 128;
        }
        else if (size <= 384)
        {
            result = 256;
        }
        else if (size <= 768)
        {
            result = 512;
        }
        else if (size <= 1536)
        {
            result = 1024;
        }
        else if (size <= 3072)
        {
            result = 2048;
        }

        return result;
    }

    public static void DoAssetReimport(string path, ImportAssetOptions options)
    {
        try
        {
            AssetDatabase.StartAssetEditing();
            AssetDatabase.ImportAsset(path, options);
        }
        finally
        {
            AssetDatabase.StopAssetEditing();
        }
    }

    #endregion