Unity保存一组sprite为spritesheet

背景

之前尝试在Unity编辑器用代码读取打包好的数据，发现在布置场景的时候不能做到所见即所得，这里将运行时读取到的图片素材，保存为spritesheet，并设置对应的sprite。

效果展示

代码

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using UnityEditor;
using UnityEditor.U2D.Sprites;
using UnityEngine;
using static AvatarSpriteGenerate;


#if UNITY_EDITOR

public class SpriteSheet
{
    public List<Sprite> spriteList;
    public string filePath;
}

internal class SpriteSheetToPNG
{

    public static void Save(SpriteSheet spriteSheet)
    {
        var folderPath = Path.GetDirectoryName(spriteSheet.filePath);
        if (!Directory.Exists(folderPath))
            Directory.CreateDirectory(folderPath);

        var rectList = SaveAndGetRect(spriteSheet);
        SetSheet(spriteSheet, rectList);

    }

    private static List<Rect> SaveAndGetRect(SpriteSheet spriteSheet)
    {
        var textureList = new List<Texture2D>();
        foreach (var sprite in spriteSheet.spriteList)
            textureList.Add(sprite.texture);

        Texture2D atlas = new Texture2D(2048, 2048);
        var rects = atlas.PackTextures(textureList.ToArray(), 2, 2048);

        var rectList = new List<Rect>();
        foreach(var rect in rects)
        {
            // PackTextures函数返回的值是相对百分比，需要转化为像素单位
            var xMin = rect.xMin * atlas.width;
            var xMax = rect.xMax * atlas.width;
            var yMin = rect.yMin * atlas.height;
            var yMax = rect.yMax * atlas.height;

            var result = new Rect
            {
                xMin = xMin,
                xMax = xMax,
                yMin = yMin,
                yMax = yMax
            };
            rectList.Add(result);
        }

        byte[] bytes = atlas.EncodeToPNG();
        File.WriteAllBytes(spriteSheet.filePath, bytes);
        var filePath = Path.GetRelativePath(System.Environment.CurrentDirectory, spriteSheet.filePath);
        AssetDatabase.ImportAsset(filePath);
        return rectList;

    }

    private static void SetSheet(SpriteSheet spriteSheet, List<Rect> rectList)
    {
        var filePath = Path.GetRelativePath(System.Environment.CurrentDirectory, spriteSheet.filePath);

        TextureImporter textureImporter = AssetImporter.GetAtPath(filePath) as TextureImporter;
        textureImporter.spriteImportMode = SpriteImportMode.Multiple;
        textureImporter.SaveAndReimport();



        var obj = AssetDatabase.LoadAssetAtPath(filePath, typeof(Texture2D));

        var factory = new SpriteDataProviderFactories();
        factory.Init();
        var dataProvider = factory.GetSpriteEditorDataProviderFromObject(obj);
        dataProvider.InitSpriteEditorDataProvider();

        /* Use the data provider */
        List<SpriteRect> spriteRectList = new List<SpriteRect>();

        for (int i = 0; i < rectList.Count; ++i)
        {
            var rect = rectList[i];
            var sprite = spriteSheet.spriteList[i];

            SpriteRect spriteRect = new SpriteRect();
            spriteRect.rect = rect;
            spriteRect.spriteID = GUID.Generate();
            //sprite.pivot返回的是像素单位，需要转为百分比
            spriteRect.pivot = new Vector2(sprite.pivot.x/ sprite.texture.width, sprite.pivot.y/sprite.texture.height);
            spriteRect.alignment = SpriteAlignment.Custom;
            spriteRect.name = sprite.name;

            spriteRectList.Add(spriteRect);

        }

        dataProvider.SetSpriteRects(spriteRectList.ToArray());
        dataProvider.Apply();

        // Reimport the asset to have the changes applied
        var assetImporter = dataProvider.targetObject as AssetImporter;
        assetImporter.SaveAndReimport();

    }


}

#endif