Unity工程里图片的RGB和Alpha通道的分离

图片的RGB和Alpha通道的分离经常会碰到，那么要怎么实现呢，对于经验少的同学来说可能比较棘手，为此，下面就给大家介绍下Unity工程里图片的RGB和Alpha通道的分离方法。

1. 处理Alpha贴图时是一个像素一个像素地处理，用Texture.SetPixel()函数。推荐批量处理，用Texture.SetPixels()函数。推荐批量处理，用Texture.SetPixels()函数。”

改进之：

using UnityEngine;    
using System.Collections;    
using System.Collections.Generic;    
using UnityEditor;    
using System.IO;    
using System.Reflection;    
public class MaterialTextureForETC1_new｛  
    private static string defaultWhiteTexPath_relative = "Assets/Default_Alpha.png";  
    private static Texture2D defaultWhiteTex = null;  
    [MenuItem("EffortForETC1/Depart RGB and Alpha Channel")]  
    static void SeperateAllTexturesRGBandAlphaChannel()  
    ｛  
        Debug.Log("Start Departing.");  
        if (!GetDefaultWhiteTexture())  
        ｛  
            return;  
        ｝        
        string[] paths = Directory.GetFiles(Application.dataPath, "*.*", SearchOption.AllDirectories);  
        foreach (string path in paths)  
        ｛  
            if (!string.IsNullOrEmpty(path) && IsTextureFile(path) && !IsTextureConverted(path))   //full name    
            ｛  
                SeperateRGBAandlphaChannel(path);  
            ｝  
        ｝  
        AssetDatabase.Refresh();    //Refresh to ensure new generated RBA and Alpha textures shown in Unity as well as the meta file  
        Debug.Log("Finish Departing.");  
    ｝  
    #region process texture  
    static void SeperateRGBAandlphaChannel(string _texPath)  
    ｛  
        string assetRelativePath = GetRelativeAssetPath(_texPath);  
        SetTextureReadableEx(assetRelativePath);    //set readable flag and set textureFormat TrueColor  
        Texture2D sourcetex = AssetDatabase.LoadAssetAtPath(assetRelativePath, typeof(Texture2D)) as Texture2D;  //not just the textures under Resources file    
        if (!sourcetex)  
        ｛  
            Debug.LogError("Load Texture Failed : "   assetRelativePath);  
            return;  
        ｝  
        TextureImporter ti = null;  
        try  
        ｛  
            ti = (TextureImporter)TextureImporter.GetAtPath(assetRelativePath);  
        ｝  
        catch  
        ｛  
            Debug.LogError("Load Texture failed: "   assetRelativePath);  
            return;  
        ｝  
        if (ti == null)  
        ｛  
            return;  
        ｝    
        bool bGenerateMipMap = ti.mipmapEnabled;    //same with the texture import setting        
        Texture2D rgbTex = new Texture2D(sourcetex.width, sourcetex.height, TextureFormat.RGB24, bGenerateMipMap);  
        rgbTex.SetPixels(sourcetex.GetPixels());  
        Texture2D mipMapTex = new Texture2D(sourcetex.width, sourcetex.height, TextureFormat.RGBA32, true);  //Alpha Channel needed here  
        mipMapTex.SetPixels(sourcetex.GetPixels());  
        mipMapTex.Apply();  
        Color[] colors2rdLevel = mipMapTex.GetPixels(1);   //Second level of Mipmap  
        Color[] colorsAlpha = new Color[colors2rdLevel.Length];  
        if (colors2rdLevel.Length != (mipMapTex.width 1) / 2 * (mipMapTex.height 1) / 2)  
        ｛  
            Debug.LogError("Size Error.");  
            return;  
        ｝  
        bool bAlphaExist = false;  
        for (int i = 0; i < colors2rdLevel.Length;  i)  
        ｛  
            colorsAlpha[i].r = colors2rdLevel[i].a;  
            colorsAlpha[i].g = colors2rdLevel[i].a;  
            colorsAlpha[i].b = colors2rdLevel[i].a;  
            if (!Mathf.Approximately(colors2rdLevel[i].a, 1.0f))  
            ｛  
                bAlphaExist = true;  
            ｝  
        ｝  
        Texture2D alphaTex = null;  
        if (bAlphaExist)  
        ｛  
            alphaTex = new Texture2D((sourcetex.width 1) / 2, (sourcetex.height 1) / 2, TextureFormat.RGB24, bGenerateMipMap);  
        ｝  
        else  
        ｛  
            alphaTex = new Texture2D(defaultWhiteTex.width, defaultWhiteTex.height, TextureFormat.RGB24, false);  
        ｝  
        alphaTex.SetPixels(colorsAlpha);  
        rgbTex.Apply();  
        alphaTex.Apply();  
        byte[] bytes = rgbTex.EncodeToPNG();  
        File.WriteAllBytes(assetRelativePath, bytes);  
        byte[] alphabytes = alphaTex.EncodeToPNG();  
        string alphaTexRelativePath = GetAlphaTexPath(_texPath);  
        File.WriteAllBytes(alphaTexRelativePath, alphabytes);  
        ReImportAsset(assetRelativePath, rgbTex.width, rgbTex.height);  
        ReImportAsset(alphaTexRelativePath, alphaTex.width, alphaTex.height);  
        Debug.Log("Succeed Departing : "   assetRelativePath);  
    ｝  
    static void ReImportAsset(string path, int width, int height)  
    ｛  
        try  
        ｛  
            AssetDatabase.ImportAsset(path);  
        ｝  
        catch  
        ｛  
            Debug.LogError("Import Texture failed: "   path);  
            return;  
        ｝  
        TextureImporter importer = null;  
        try  
        ｛  
            importer = (TextureImporter)TextureImporter.GetAtPath(path);  
        ｝  
        catch  
        ｛  
            Debug.LogError("Load Texture failed: "   path);  
            return;  
        ｝  
        if (importer == null)  
        ｛  
            return;  
        ｝  
        importer.maxTextureSize = Mathf.Max(width, height);  
        importer.anisoLevel = 0;  
        importer.isReadable = false;  //increase memory cost if readable is true  
        importer.textureFormat = TextureImporterFormat.AutomaticCompressed;  
        importer.textureType = TextureImporterType.Image;  
        if (path.Contains("/UI/"))  
        ｛  
            importer.textureType = TextureImporterType.GUI;  
        ｝  
        AssetDatabase.ImportAsset(path);  
    ｝  
    static void SetTextureReadableEx(string _relativeAssetPath)    //set readable flag and set textureFormat TrueColor  
    ｛  
        TextureImporter ti = null;  
        try  
        ｛  
            ti = (TextureImporter)TextureImporter.GetAtPath(_relativeAssetPath);  
        ｝          catch  
        ｛  
            Debug.LogError("Load Texture failed: "   _relativeAssetPath);  
            return;  
        ｝  
        if (ti == null)  
        ｛  
            return;  
        ｝         
        ti.isReadable = true;  
        ti.textureFormat = TextureImporterFormat.AutomaticTruecolor;      //this is essential for departing Textures for ETC1. No compression format for following operation.  
        AssetDatabase.ImportAsset(_relativeAssetPath);  
    ｝  
    static bool GetDefaultWhiteTexture()  
    ｛  
        defaultWhiteTex = AssetDatabase.LoadAssetAtPath(defaultWhiteTexPath_relative, typeof(Texture2D)) as Texture2D;  //not just the textures under Resources file    
        if (!defaultWhiteTex)  
        ｛  
            Debug.LogError("Load Texture Failed : "   defaultWhiteTexPath_relative);  
            return false;  
        ｝  
        return true;  
    ｝  
    #endregion    
    #region string or path helper    
    static bool IsTextureFile(string _path)    
    ｛    
        string path = _path.ToLower();    
        return path.EndsWith(".psd") || path.EndsWith(".tga") || path.EndsWith(".png") || path.EndsWith(".jpg") || path.EndsWith(".bmp") || path.EndsWith(".tif") || path.EndsWith(".gif");    
    ｝  
    static bool IsTextureConverted(string _path)  
    ｛  
        return _path.Contains("_RGB.") || _path.Contains("_Alpha.");  
    ｝  
    static string GetRGBTexPath(string _texPath)    
    ｛    
        return GetTexPath(_texPath, "_RGB.");    
    ｝    
    static string GetAlphaTexPath(string _texPath)    
    ｛    
        return GetTexPath(_texPath, "_Alpha.");    
    ｝    
    static string GetTexPath(string _texPath, string _texRole)    
    ｛  
        string dir = System.IO.Path.GetDirectoryName(_texPath);  
        string filename = System.IO.Path.GetFileNameWithoutExtension(_texPath);  
        string result = dir   "/"   filename   _texRole   "png";  
        return result;    
    ｝    
    static string GetRelativeAssetPath(string _fullPath)    
    ｛    
        _fullPath = GetRightFormatPath(_fullPath);    
        int idx = _fullPath.IndexOf("Assets");    
        string assetRelativePath = _fullPath.Substring(idx);    
        return assetRelativePath;    
    ｝    
    static string GetRightFormatPath(string _path)    
    ｛    
        return _path.Replace("\\", "/");    
    ｝    
    #endregion       
｝