Unity 定制图集打包

using System.IO;
using UnityEditor;

public class TextureAssetPostprocessor : AssetPostprocessor
{
    void OnPreprocessTexture()
    {
        if (!assetPath.StartsWith("Assets/UI"))
            return;

        var textureImporter = assetImporter as TextureImporter;

        var atlasName = new DirectoryInfo(Path.GetDirectoryName(assetPath)).Name;
        textureImporter.spritePackingTag = atlasName;
        textureImporter.mipmapEnabled = false;
    }
}

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

public class CustomPackerPolicy : IPackerPolicy
{
    public int GetVersion()
    {
        return 1;
    }

    public void OnGroupAtlases(BuildTarget target, PackerJob job, int[] textureImporterInstanceIDs)
    {
        var assets = new HashSet<string>();//存储有被场景引用的资源
        var scenes = AssetDatabase.FindAssets("t:SceneAsset");
        for (var i = 0; i < scenes.Length; i++)
        {
            var guid = scenes[i];
            var assetPath = AssetDatabase.GUIDToAssetPath(guid);

            EditorUtility.DisplayProgressBar("AssetDatabase.GetDependencies", assetPath, 1.0f * i / scenes.Length);

            var dependencies = AssetDatabase.GetDependencies(assetPath);
            foreach (var dependency in dependencies)
            {
                if (!assets.Contains(dependency))
                    assets.Add(dependency);
            }
        }

        var groups = new Dictionary<string, List<Sprite>>();

        for (var i = 0; i < textureImporterInstanceIDs.Length; i++)
        {
            var instanceID = textureImporterInstanceIDs[i];
            var textureImporter = EditorUtility.InstanceIDToObject(instanceID) as TextureImporter;

            EditorUtility.DisplayProgressBar("AssetDatabase.LoadAssetAtPath", textureImporter.assetPath, 1.0f * i / scenes.Length);

            if (!assets.Contains(textureImporter.assetPath))
                continue;

            var sprite = AssetDatabase.LoadAssetAtPath<Sprite>(textureImporter.assetPath);

            if (!groups.ContainsKey(textureImporter.spritePackingTag))
                groups.Add(textureImporter.spritePackingTag, new List<Sprite>());

            groups[textureImporter.spritePackingTag].Add(sprite);
        }

        foreach (var group in groups)
        {
            EditorUtility.DisplayProgressBar("AddAtlas", group.Key, 0.5f);

            job.AddAtlas(group.Key, new AtlasSettings()
            {
                format = TextureFormat.ETC2_RGBA8,
                maxWidth = 4096,
                maxHeight = 4096,
                //enableRotation = true
            });

            foreach (var sprite in group.Value)
            {
                job.AssignToAtlas(group.Key, sprite, SpritePackingMode.Tight, SpritePackingRotation.None);
            }
        }

        EditorUtility.ClearProgressBar();
    }
}