1.AssetPostProcessor之OnPreprocess和OnPostprocess区别：
磁盘上的资源，并不是Unity使用的资源。在编辑器模式下，Unity会把我们放进去的外部资源Asset转换成一种Unity内部格式的资源，存储在Library/metadata路径下对应该Asset的GUID命名的文件，这个过程就是资源导入。
AssetPostProcessor是一个编辑器类，用来管理资源导入，当资源导入之前和之后都会发送通知，可以根据不同的资源类型，在导入之前和之后做不同的处理，来修改Untiy内部格式资源。一般我们通过这个类中OnPreprocess和OnPostprocess消息处理函数来修改资源数据和设置，这两者的区别可以简单理解为：
OnPreprocess用来改变资源报错在meta中的序列化信息，也就是说大部分是Inspector视图可见的选项。
OnPostprocess为导入过程中的一些处理，结果保存在最终的Library/metadata中，是和序列化无关的。
2.几个常用API：
//模型导入之前调用
public void OnPreprocessModel() { }
//模型导入之后调用
public void OnPostprocessModel(GameObject go){ }
//Texture导入之前调用，针对Texture进行设置
public void OnPreprocessTexture() { }
//Texture导入之后调用，针对Texture进行设置
public void OnPostprocessTexture(Texture2D tex){}
//导入Audio后操作
public void OnPostprocessAudio(AudioClip clip) {}
//导入Audio前操作
public void OnPreprocessAudio(){ }
//所有的资源的导入，删除，移动，都会调用此方法，注意，这个方法是static的
public static void OnPostprocessAllAssets(string[]importedAsset,string[] deletedAssets,string[] movedAssets,string[]movedFromAssetPaths)
{
Debug.Log ("OnPostprocessAllAssets");
foreach (string str in importedAsset) {
Debug.Log("importedAsset = "+str);
}
foreach (string str in deletedAssets) {
Debug.Log("deletedAssets = "+str);
}
foreach (string str in movedAssets) {
Debug.Log("movedAssets = "+str);
}
foreach (string str in movedFromAssetPaths) {
Debug.Log("movedFromAssetPaths = "+str);
}
}3.导入工具，自动化设置：
自动化优化导入的模型动画选项：
可以根据项目具体规划动态修改,需要放到Editor-scripts文件夹里面
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
public class RigModelAutoImport : AssetPostprocessor {
//美术资源路径
//资源路径可以增加和修改，并在方法中添加if语句
private static string modelRoot = "Assets/Model";
private static string staticModelRoot = "Assets/Model/staticModel";
private static string animationRoot = "Assets/Animation";
//网格导入器, pre-process
void OnPreprocessModel()
{
//获得importer实例
ModelImporter mImporter = assetImporter as ModelImporter;
//——————————————模型部分
//不要勾选Read/Write Enabled。我们使用特殊命名“_ReadWrite”无视这个规则，大家用目录来划分也可以
mImporter.isReadable = mImporter.assetPath.Contains("_ReadWrite");
//OptimizeMesh:顶点优化选项GPU性能可以得到提升
mImporter.optimizeMesh = true;
//其它不必要的数据导入关闭
mImporter.importLights = false;
mImporter.importCameras = false;
//顶点包含Normals，不要Tangents。实际应用按照路径规划动态调整
mImporter.importNormals = ModelImporterNormals.Import;
mImporter.importTangents = ModelImporterTangents.None;
//generateSecondaryUV第二套uv（光照UV）启用默认开启状态
if (mImporter.assetPath.StartsWith(staticModelRoot))
{
//模型皆为静态时自动勾选静态
//注意：模型静态勾选生成UV时间根据模型数据大小决定，开启此选项可能占用太多时间
mImporter.generateSecondaryUV = true;
mImporter.secondaryUVAngleDistortion = 8;
mImporter.secondaryUVAreaDistortion = 15;
mImporter.secondaryUVHardAngle = 88;
mImporter.secondaryUVPackMargin = 4;
}
//关闭Material导入
mImporter.importMaterials = false;
}
//网格和动画导入器, post-process
void OnPostprocessModel(GameObject go)
{
//获得importer实例
ModelImporter mImporter = assetImporter as ModelImporter;
//模型后处理部分
if (mImporter.assetPath.StartsWith(modelRoot))
{
//自动去无用骨骼节点，例如后缀为"Nub"
Transform[] transforms = go.GetComponentsInChildren<Transform> ();
foreach(Transform t in transforms)
{
if(t.gameObject.name.EndsWith ("Nub"))
{
GameObject.DestroyImmediate (t.gameObject);
}
}
}
//动画后处理部分
if (mImporter.assetPath.StartsWith(animationRoot))
{
List<AnimationClip> animationClipList = new List<AnimationClip>(AnimationUtility.GetAnimationClips(go));
if (animationClipList.Count == 0) {
AnimationClip[] objectList = UnityEngine.Object.FindObjectsOfType (typeof(AnimationClip)) as AnimationClip[];
animationClipList.AddRange(objectList);
}
foreach (AnimationClip theAnimation in animationClipList)
{
try
{
//如果文件命名没有包含_Scale，则去除scale曲线
if (!assetPath.Contains("_Scale"))
{
foreach (EditorCurveBinding theCurveBinding in AnimationUtility.GetCurveBindings(theAnimation))
{
string name = theCurveBinding.propertyName.ToLower();
if (name.Contains("scale"))
{
AnimationUtility.SetEditorCurve(theAnimation, theCurveBinding, null);
}
}
}
//浮点数精度压缩为f4
AnimationClipCurveData[] curves = null;
curves = AnimationUtility.GetAllCurves(theAnimation);
Keyframe key;
Keyframe[] keyFrames;
for (int ii = 0; ii < curves.Length; ++ii)
{
AnimationClipCurveData curveDate = curves[ii];
if (curveDate.curve == null || curveDate.curve.keys == null)
{
continue;
}
keyFrames = curveDate.curve.keys;
for (int i = 0; i < keyFrames.Length; i++)
{
key = keyFrames[i];
key.value = float.Parse(key.value.ToString("f4"));
key.inTangent = float.Parse(key.inTangent.ToString("f4"));
key.outTangent = float.Parse(key.outTangent.ToString("f4"));
keyFrames[i] = key;
}
curveDate.curve.keys = keyFrames;
theAnimation.SetCurve(curveDate.path, curveDate.type, curveDate.propertyName, curveDate.curve);
}
}
catch (System.Exception e)
{
Debug.LogError(string.Format("CompressAnimationClip Failed! animationPath : {0} error: {1}", assetPath, e));
}
}
}
}
}自动化优化导入的纹理选项：
using UnityEngine;
using UnityEditor;
using System.Text.RegularExpressions;
using System.IO;
public class TextureaAutoImport : AssetPostprocessor {
//纹理导入器, pre-process
void OnPreprocessTexture()
{
//获得importer实例
TextureImporter texImporter = assetImporter as TextureImporter;
//设置Read/Write Enabled开关,不勾选
texImporter.isReadable = false;
if (texImporter.assetPath.StartsWith("Assets/TexturesIsUI"))
{
//设置UI纹理Generate Mipmaps
texImporter.mipmapEnabled = false;
//设置UI纹理WrapMode
texImporter.wrapMode = TextureWrapMode.Clamp;
}
//设置压缩格式,其它平台可根据规划在这里添加
TextureImporterPlatformSettings psAndroid = texImporter.GetPlatformTextureSettings("Android");
TextureImporterPlatformSettings psIPhone = texImporter.GetPlatformTextureSettings("iPhone");
psAndroid.overridden = true;
psIPhone.overridden = true;
if (texImporter.DoesSourceTextureHaveAlpha())
{
psAndroid.format = TextureImporterFormat.ETC2_RGBA8;
psIPhone.format = TextureImporterFormat.ASTC_RGBA_4x4;
}
else
{
psAndroid.format = TextureImporterFormat.ETC2_RGB4;
psIPhone.format = TextureImporterFormat.ASTC_RGB_4x4;
}
texImporter.SetPlatformTextureSettings(psAndroid);
texImporter.SetPlatformTextureSettings(psIPhone);
}
}