判断资源贴图是否有alpha

/*
  modfly selected textures`s maxSize and ImportFormat
  bool hasAlpha = true;
  if(hasAlpha)then(texture.size/2 and trueColor)else(16bit)

  2014.05.27
*/

using UnityEngine;
using System.Collections;
using UnityEditor;
public class modflyTextures : ScriptableObject{

    [MenuItem ("Custom/modflyTextures")]
    static void processTexture_Auto() {
        processTexture();
    }

    static void processTexture() { 

        Object[] textures = GetSelectedTextures();
        Selection.objects = new Object[];
        foreach (Texture2D tex in textures)  {
            string path = AssetDatabase.GetAssetPath(tex);
            TextureImporter importerTexture = AssetImporter.GetAtPath(path) as TextureImporter; 

            if(importerTexture.DoesSourceTextureHaveAlpha() ==  true){
                if(tex.width >= tex.height )
                    importerTexture.maxTextureSize = tex.width/;
                else importerTexture.maxTextureSize = tex.height/;

                importerTexture.textureFormat = TextureImporterFormat.AutomaticTruecolor;
            }else{
                if(tex.width >= tex.height )
                    importerTexture.maxTextureSize = tex.width;
                else importerTexture.maxTextureSize = tex.height;

                importerTexture.textureFormat = TextureImporterFormat.AutomaticCompressed;
            }
            AssetDatabase.ImportAsset(path);
        }
    }

    static Object[] GetSelectedTextures()
    {
        return Selection.GetFiltered(typeof(Texture2D), SelectionMode.DeepAssets);
    }
}