Unity3d 批量修改纹理格式

决定纹理资源大小的因素主要有三种：分辨率、格式和Mipmap是否开启。
对于纹理资源的加载建议如下：

1、严格控制RGBA32和ARGB32纹理的使用，在保证视觉效果的前提下，尽可能采用“够用就好”的原则，降低纹理资源的分辨率，以及使用硬件支持的纹理格式。
2、在硬件格式（ETC、PVRTC）无法满足视觉效果时，RGBA16格式是一种较为理想的折中选择，既可以增加视觉效果，又可以保持较低的加载耗时。
3、严格检查纹理资源的Mipmap功能，特别注意UI纹理的Mipmap是否开启。有不少项目的UI纹理均开启了Mipmap功能，不仅造成了内存占用上的浪费，同时也增加了不小的加载时间。
4、ETC2对于支持OpenGL ES3.0的Android移动设备来说，是一个很好的处理半透明的纹理格式。但是，如果你的游戏需要在大量OpenGL ES2.0的设备上进行运行，那么我们不建议使用ETC2格式纹理。因为不仅会造成大量的内存占用（ETC2转成RGBA32），同时也增加一定的加载时间。下图为测试2中所用的测试纹理在三星S3和S4设备上加载性能表现。可以看出，在OpenGL ES2.0设备上，ETC2格式纹理的加载要明显高于ETC1格式，且略高于RGBA16格式纹理。因此，建议研发团队在项目中谨慎使用ETC2格式纹理。
文章 加载模块深度解析 对图片的使用格式的方法进行了详细描述

批量检测和修改纹理格式代码如下：

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

public partial class ResourceExporter
{

    static List GetAllTex(bool bFilter, CheckPlatformTexFormat checkAndroid, CheckPlatformTexFormat checkIphone, ReplacePlatformTexFormat replaceAction = null)
    {
        List<string> texPathLs = new List<string>();
        GetAssetsTexInSubFolderForAtlas("assets", ref texPathLs);
        List infoLs = new List();
        int totalCount = texPathLs.Count;
        if (texPathLs.Count>0)
        {
            int iCurCount = 0;
            foreach (var path in texPathLs)
            {
                TextureImporter texImporter = TextureImporter.GetAtPath(path) as TextureImporter;
                if (null != texImporter)
                {
                    TextureFormatInfo texFormatInfo = new TextureFormatInfo(texImporter.assetPath);
                    texImporter.GetPlatformTextureSettings("Standalone", out texFormatInfo.windowsMaxSize, out texFormatInfo.texFormatWindows);
                    texImporter.GetPlatformTextureSettings("iPhone", out texFormatInfo.iphoneMaxSize, out texFormatInfo.texFormatIphone);
                    texImporter.GetPlatformTextureSettings("Android", out texFormatInfo.androidMaxSize, out texFormatInfo.texFormatAndroid);
                    texFormatInfo.bMipMapEnabled = texImporter.mipmapEnabled;
                    bool bAdd = true;
                    texFormatInfo.bNeedAndroidFormat = checkAndroid(texFormatInfo.texFormatAndroid);
                    texFormatInfo.bNeedIphoneFormat = checkIphone(texFormatInfo.texFormatIphone);
                    if (bFilter)
                    {
                        bAdd = texFormatInfo.bMipMapEnabled || (!texFormatInfo.bNeedAndroidFormat) || (!texFormatInfo.bNeedIphoneFormat);
                    }

                    if (bAdd)
                    {
                        Debug.Log(texFormatInfo.ToString());
                        if (null != replaceAction)
                        {
                            replaceAction(texImporter,texFormatInfo);
                        }
                        infoLs.Add(texFormatInfo);
                    }
                }
                EditorUtility.DisplayCancelableProgressBar("Check TexFormat", "Wait......", (++iCurCount) * 1f / totalCount);
            }
        }
        totalCount = infoLs.Count;
        Debug.Log("PathCount:" + texPathLs.Count);
        Debug.Log("InfoCount:" + infoLs.Count);

        EditorUtility.ClearProgressBar();
        return infoLs;
    }

    static void SaveTextureFormatInfoPath(List infoLs)
    {
        string fileSavePath = "../AllTextureFormatInfoPath";
        int totalCount = infoLs.Count;
        using (StreamWriter sw = File.CreateText(fileSavePath + ".html"))
        {
            sw.WriteLine("size = " + totalCount + "
");
            foreach (var info in infoLs)
            {
                sw.WriteLine(info.ToHtmlString());
            }
            sw.Close();
        }
    }

    static bool CheckAndroidFormat(TextureImporterFormat format)
    {
        return format == TextureImporterFormat.ETC_RGB4;
    }

    static bool CheckIphoneFormat(TextureImporterFormat format)
    {
        return format.ToString().Contains("PVRTC");
    }

    delegate bool CheckPlatformTexFormat(TextureImporterFormat format);

    delegate void ReplacePlatformTexFormat(TextureImporter textureImporter,TextureFormatInfo texInfo);

    static void ReplacePlatformFormat(TextureImporter textureImporter, TextureFormatInfo texInfo)
    {
        textureImporter.mipmapEnabled = false;
        textureImporter.SetPlatformTextureSettings("Android", texInfo.androidMaxSize, TextureImporterFormat.ETC_RGB4);
        AssetDatabase.ImportAsset(textureImporter.assetPath);
    }

    class TextureFormatInfo
    {
        public string path;
        public bool bMipMapEnabled;
        public bool bNeedAndroidFormat;
        public bool bNeedIphoneFormat;
        public TextureImporterFormat texFormatIphone;
        public TextureImporterFormat texFormatAndroid;
        public TextureImporterFormat texFormatWindows;
        public int androidMaxSize;
        public int iphoneMaxSize;
        public int windowsMaxSize;

        public TextureFormatInfo(string filePath)
        {
            path = filePath;
        }

        public string ToString()
        {
            string strFormat = "{0}: MipMapEnabled:{1},\nAndroid:{2},\nIphone:{3}";

            return string.Format(strFormat, path, bMipMapEnabled, texFormatAndroid, texFormatIphone, texFormatWindows);
        }

        public string ToHtmlString()
        {
            // size = 2357 

            string strFormat = "{0}:           {1},           {2},           {3}
";

            string bMipStr = string.Format("MipMapEnabled:{0}", bMipMapEnabled);
            string parm1 = bMipMapEnabled ? GetSpecialTip(bMipStr, "red") : bMipStr;
            string androidStr = string.Format("Android:{0}", texFormatAndroid);
            string parm2 = !bNeedAndroidFormat ? GetSpecialTip(androidStr, "blue") : androidStr;
            string iphoneStr = string.Format("Iphone:{0}", texFormatIphone);
            string parm3 = !bNeedIphoneFormat ? GetSpecialTip(iphoneStr, "YellowGreen") : iphoneStr;
            return string.Format(strFormat, path, parm1, parm2, parm3);
        }

        private string GetSpecialTip(string name,string fontColor)
        {
            return string.Format("{1}", fontColor, name);
        }
    }
static void GetAssetsTexInSubFolderForAtlas(string srcFolder, ref List<string> atlas)
    {
        string searchPattern0 = "*.png";
        string searchPattern1 = "*.tga";
        string searchPattern2 = "*.psd";
        string searchFolder = srcFolder.Replace(@"\", @"/");
        string searchDir0 = searchFolder;
        if (Directory.Exists(searchDir0))
        {
            //string[] files = Directory.GetFiles(searchDir0, searchPattern);
            AddFilePathToList(Directory.GetFiles(searchDir0, searchPattern0), ref atlas);
            AddFilePathToList(Directory.GetFiles(searchDir0, searchPattern1),ref atlas);
            AddFilePathToList(Directory.GetFiles(searchDir0, searchPattern2),ref atlas);
        }

        string[] dirs = Directory.GetDirectories(searchFolder);
        foreach (string oneDir in dirs)
        {
            GetAssetsTexInSubFolderForAtlas(oneDir, ref atlas);
        }
    }

    static void AddFilePathToList(string[] files, ref List<string> ls)
    {
        foreach (string oneFile in files)
        {
            string srcFile = oneFile.Replace(@"\", @"/");
            string lowerFile = srcFile.ToLower();
            ls.Add(lowerFile);
        }
    }
    [MenuItem("MyEditor/Check Texture Format")]

    public static void CheckTextureFormat()
    {
        List infoLs = GetAllTex(true, CheckAndroidFormat, CheckIphoneFormat);
        SaveTextureFormatInfoPath(infoLs);
    }

    [MenuItem("MyEditor/Replace Texture Format")]
    public static void ReplaceTextureFormat()
    {
        GetAllTex(true, CheckAndroidFormat, CheckIphoneFormat, ReplacePlatformFormat);
        //SaveTextureFormatInfoPath(infoLs);
    }
}