工程

示例代码

using UnityEngine;
using UnityEditor;
using System;
using System.IO;
using System.Collections;

public class MenuEditor {

    [MenuItem("Tool/Texture SplitAlphaChannel ")]
    static void SplitAlphaChannel()
    {
        Texture2D tex = Selection.activeObject as Texture2D;
        if (null == tex)
            return;
        
        string texPath = AssetDatabase.GetAssetPath(tex);
        string texDir = Path.GetDirectoryName(texPath);
        string texName = Path.GetFileNameWithoutExtension(texPath);

        //获取选中的Texture并设置导入参数
        AssetImporter importer = AssetImporter.GetAtPath(texPath);
        TextureImporter texImporter = importer as TextureImporter;
        if (!texImporter.DoesSourceTextureHaveAlpha())
        {
            Debug.Log("当前选中的纹理图片没Alpha通道");
            return;
        }
        texImporter.textureType = TextureImporterType.Advanced;
        texImporter.isReadable = true;//开启读写
        AssetDatabase.ImportAsset(texPath);
        
        Color32[] colors32 = tex.GetPixels32();

        //创建RGB Texture
        Texture2D texrgb = new Texture2D(tex.width, tex.height, TextureFormat.RGB24, false);
        texrgb.SetPixels32(colors32);
        texrgb.Apply();
        //保存RGB Texture
        string texrgbPath = string.Format("{0}/Atlas/{1}_rgb.png", texDir, texName);
        SavePNG(texrgbPath, texrgb);

        for (int i = 0; i < colors32.Length; i++) {
            colors32[i].r = colors32[i].a;
            colors32[i].g = colors32[i].a;
            colors32[i].b = colors32[i].a;
        }

        //创建Alpha Texture
        Texture2D texalpha = new Texture2D(tex.width, tex.height, TextureFormat.RGB24, true);
        texalpha.SetPixels32(colors32);
        texalpha.Apply();
        //保存Alpha Texture        
        string texalphaPath = string.Format("{0}/Atlas/{1}_alpha.png", texDir, texName);
        SavePNG(texalphaPath, texalpha);
        
        //平台设置
        SetPlatformTextureSettings(texrgbPath);
        SetPlatformTextureSettings(texalphaPath);

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

    //平台设置
    static void SetPlatformTextureSettings(string path)
    {
        TextureImporter texImporter = AssetImporter.GetAtPath(path) as TextureImporter;
        texImporter.textureType = TextureImporterType.Advanced;
        texImporter.mipmapEnabled = false;
        int maxSize = 1024;
        int quality = (int)TextureCompressionQuality.Normal;
        //平台字符串 "Standalone", "iPhone", "Android", "WebGL", "Windows Store Apps", "PSP2", "PS4", "XboxOne", "Nintendo 3DS", "WiiU", "tvOS"
        texImporter.SetPlatformTextureSettings("Standalone", maxSize, TextureImporterFormat.DXT5, quality);
        texImporter.SetPlatformTextureSettings("iPhone", maxSize, TextureImporterFormat.PVRTC_RGBA4, quality);
        texImporter.SetPlatformTextureSettings("Android", maxSize, TextureImporterFormat.ETC_RGB4, quality);
        //texImporter.SetPlatformTextureSettings("Android", 1024, TextureImporterFormat.ETC2_RGBA8);//OpenGL ES 3.0才支持ETC2(支持Alpha通道)
    }

    //保存Texture
    static void SavePNG(string filePath, Texture2D texture)
    {
        if (null == texture)
            return;

        try
        {
            string dir = Path.GetDirectoryName(filePath);
            if (!Directory.Exists(dir))
                Directory.CreateDirectory(dir);

            byte[] pngData = texture.EncodeToPNG();
            File.WriteAllBytes(filePath, pngData);
        }
        catch (Exception ex)
        {
            Debug.Log(ex.StackTrace);
        }
    }
}

效果