Unity内存优化(贴图层面)

发表于2016-05-11
评论1 4.5k浏览
一、聊聊近况:
  距离上一篇文章已经过了好久,主要原因是我懒了。公司项目也到了开始优化的阶段,上网找的资料,看过了就忘。还是想把它整理一下,写出来。其实我说的东西,网上都有,我只是搬运工而已。

二、贴图压缩:
  Android平台使用ETC1格式压缩。
  目前主流的Android机型基本都支持ETC1格式压缩。但ETC1只能支持非Alpha通道的图片压缩。
  所以一般把RGB和ALPHA分离出来,r值,g值,b值从RGB图获取,a值从Alpha图里获取。
  随着OPENGL ES 3.0的发布,etc2也出了,支持Alpha通道,但就目前的市场,支持的机型还比较少,所以可以不用考虑。
  IOS平台使用PVRT压缩纹理,它支持Alpha通道。

三、工具准备:
  TexturePacker4.1.0及破解戳这里:链接:http://pan.baidu.com/s/1qYKNIQ4 密码:s21o
  我的第一篇文章也用过TexturePacker:http://www.shihuanjue.com/?p=16

四、实践:
1、打开TexturePacker,选择Unity-JOSN data,把美术给过来的散图拖到TexturePacker里面,调整参数,最后Publish导出图集(.tga)和小图配置信息(.txt)。


2、打开Photoshop,拖入.tga
  保存RGB图:选中Alpha 1.右键。删除该透明通道。然后将图片存储为_MainTex.png图片。


  保存ALPHA图:我们可以在菜单中后退一步。或者重新打开没有删除透明通道的图片。
  选中Alpha 1. 按Ctrl + A 全选 ,再按 Ctrl + C 复制透明通道。
  选中RGB,Ctrl + V 粘贴。
  最后删除Alpha 1 透明通道。将图片保存为_AlphaTex.png。


  我们项目还是用的还是NGUI,用NGUI做UIAtlas。


  新建一个材质球,图片用的是_MainTex.png,_AlphaTex.png
  NGUI的原生Shader,是从一张图上获取RGBA的,现在我们需要从_AlphaTex.png上获取a值。
  所以拿来改改:
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
}
}
}
}
  把一开始TP导出的.txt拖到UIAtlas的TP Import上

五、效果:



  肉眼看不出明显差别,内存却减少了不少。

六、RGB和ALPHA分离(脚本化):
  用PS去分离,太慢。尝试用脚本或者工具来自动化分离。
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     
}

七、注意点:
  图片最好2的幂次
  Read/Write Enabled 不勾
  Generate Mip Maps 不勾
  512×512的纹理对于显示效果已经够用,那么就不要使用1024×1024的纹理

八、参考:
  http://www.manew.com/thread-49730-1-1.html?_dsign=9e029b68 手机游戏开发中如何选择适合的纹理格式
  http://mp.weixin.qq.com/s?__biz=MzA4MDc5OTg5MA==&mid=209776006&idx=2&sn=d56d0bf4819493fa4fc452e36042890f&scene=5#rd Unity性能优化专题—腾讯牛人分享经验
  http://blog.uwa4d.com/archives/optimzation_memory_1.html 性能优化,进无止境-内存篇(上)

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