Unity内存优化（贴图层面）

Shader "Unlit/Transparent Colored ETC1"
{
    Properties
    {
        _MainTex ("rgb tex", 2D) = "black" {}
        _AlphaTex("alpha tex",2D) = "white"{}
    }
 
    SubShader
    {
        LOD 100
 
        Tags
        {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
        }
 
        Cull Off
        Lighting Off
        ZWrite Off
        Fog { Mode Off }
        Offset -1, -1
        Blend SrcAlpha OneMinusSrcAlpha
 
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
 
            #include "UnityCG.cginc"
 
            struct appdata_t
            {
                float4 vertex : POSITION;
                float2 texcoord : TEXCOORD0;
                fixed4 color : COLOR;
            };
 
            struct v2f
            {
                float4 vertex : SV_POSITION;
                half2 texcoord : TEXCOORD0;
                fixed4 color : COLOR;
            };
 
            sampler2D _MainTex;
            float4 _MainTex_ST;
 
            sampler2D _AlphaTex;
            float4 _AlphaTex_ST;
 
            v2f vert (appdata_t v)
            {
                v2f o;
                o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                o.texcoord = v.texcoord;
                o.color = v.color;
                return o;
            }
 
            fixed4 frag (v2f i) : COLOR
            {
                //fixed4 col = tex2D(_MainTex, i.texcoord) * i.color;
                //return col;
                fixed4 texcol = tex2D(_MainTex, i.texcoord); 
                fixed4 result = texcol;
                result.a = tex2D(_AlphaTex,i.texcoord).r*i.color.a;
                return result;
            }
            ENDCG
        }
    }
 
    SubShader
    {
        LOD 100
 
        Tags
        {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
        }
 
        Pass
        {
            Cull Off
            Lighting Off
            ZWrite Off
            Fog { Mode Off }
            Offset -1, -1
            ColorMask RGB
            AlphaTest Greater .01
            Blend SrcAlpha OneMinusSrcAlpha
            ColorMaterial AmbientAndDiffuse
 
            SetTexture [_MainTex]
            {
                Combine Texture * Primary
            }
        }
    }
}

using UnityEngine;  
using System.Collections;  
using System.Collections.Generic;  
using UnityEditor;  
using System.IO;  
using System.Reflection; 
 
public class MaterialTextureForETC1_Old : MonoBehaviour 
{
    public static float sizeScale = 0.5f;   //the size decrease scale for alphaTexture  
    private static string texPath = Application.dataPath+"/TestSplitTex";
 
    [MenuItem("EffortForETC1/Seperate RGB and Alpha Channel for All Textures")]  
    static void SeperateAllTexturesRGBandAlphaChannel()  
    {  
        string[] paths = Directory.GetFiles(texPath, "*.*", SearchOption.AllDirectories);  
        foreach (string path in paths)  
        {  
            if (!string.IsNullOrEmpty(path) && IsTextureFile(path))   //full name  
            {  
                SeperateRGBAandlphaChannel(path);  
            }  
        }   
    }  
 
    #region process texture  
 
    static void SeperateRGBAandlphaChannel(string _texPath)  
    {  
        string assetRelativePath = GetRelativeAssetPath(_texPath);  
        SetTextureReadable(assetRelativePath);  
        Texture2D sourcetex = AssetDatabase.LoadAssetAtPath(assetRelativePath, typeof(Texture2D)) as Texture2D;  //not just the textures under Resources file  
        if (!sourcetex)  
        {  
            Debug.Log("Load Texture Failed : " + assetRelativePath);  
            return;  
        }  
        if (!HasAlphaChannel(sourcetex))  
        {  
            Debug.Log("Texture does not have Alpha channel : " + assetRelativePath);  
            return;  
        }  
 
        Texture2D rgbTex = new Texture2D(sourcetex.width, sourcetex.height, TextureFormat.RGB24, true);  
        Texture2D alphaTex = new Texture2D((int)(sourcetex.width * sizeScale), (int)(sourcetex.height * sizeScale), TextureFormat.RGB24, true);  
 
        for (int i = 0; i < sourcetex.width; ++i)  
            for (int j = 0; j < sourcetex.height; ++j)  
        {  
            Color color = sourcetex.GetPixel(i, j);  
            Color rgbColor = color;  
            Color alphaColor = color;  
            alphaColor.r = color.a;  
            alphaColor.g = color.a;  
            alphaColor.b = color.a;  
            rgbTex.SetPixel(i, j, rgbColor);  
            alphaTex.SetPixel((int)(i * sizeScale), (int)(j * sizeScale), alphaColor);  
        }  
 
        rgbTex.Apply();  
        alphaTex.Apply();  
 
        byte[] bytes = rgbTex.EncodeToPNG();  
        File.WriteAllBytes(GetRGBTexPath(_texPath), bytes);  
        bytes = alphaTex.EncodeToPNG();  
        File.WriteAllBytes(GetAlphaTexPath(_texPath), bytes);  
        Debug.Log("Succeed to seperate RGB and Alpha channel for texture : " + assetRelativePath);  
        AssetDatabase.Refresh();
    }  
 
    static bool HasAlphaChannel(Texture2D _tex)  
    {  
        for (int i = 0; i < _tex.width; ++i)  
            for (int j = 0; j < _tex.height; ++j)  
        {  
            Color color = _tex.GetPixel(i, j);  
            float alpha = color.a;  
            if (alpha < 1.0f - 0.001f)  
            {  
                return true;  
            }  
        }  
        return false;  
    }  
 
    static void SetTextureReadable(string _relativeAssetPath)  
    {  
        string postfix = GetFilePostfix(_relativeAssetPath);  
        if (postfix == ".dds")    // no need to set .dds file.  Using TextureImporter to .dds file would get casting type error.  
        {  
            return;  
        }  
 
        TextureImporter ti = (TextureImporter)TextureImporter.GetAtPath(_relativeAssetPath);  
        ti.isReadable = true;  
        AssetDatabase.ImportAsset(_relativeAssetPath);  
    }  
 
    #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(".dds") || path.EndsWith(".bmp") || path.EndsWith(".tif") || path.EndsWith(".gif");  
    }  
 
    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 result = _texPath.Replace(".", _texRole);  
        string postfix = GetFilePostfix(_texPath);  
        return result.Replace(postfix, ".png");  
    }  
 
    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("\\", "/");  
    }  
 
    static string GetFilePostfix(string _filepath)   //including ‘.‘ eg ".tga", ".dds"  
    {  
        string postfix = "";  
        int idx = _filepath.LastIndexOf(‘.‘);  
        if (idx > 0 && idx < _filepath.Length)  
            postfix = _filepath.Substring(idx, _filepath.Length - idx);  
        return postfix;  
    }  
 
    #endregion     
}