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@shadesbelow
Last active April 8, 2024 04:24
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using System.Collections.Generic;
using System.IO;
using UnityEditor;
using UnityEditorInternal;
using UnityEngine;
// This is only useful for spritesheets that need to be automatically sliced (Sprite Editor > Slice > Automatic)
public class AutoSpriteSlicer
{
[MenuItem("Tools/Slice Spritesheets %&s")]
public static void Slice()
{
var textures = Selection.GetFiltered<Texture2D>(SelectionMode.Assets);
foreach (var texture in textures)
{
ProcessTexture(texture);
}
}
static void ProcessTexture(Texture2D texture)
{
string path = AssetDatabase.GetAssetPath(texture);
var importer = AssetImporter.GetAtPath(path) as TextureImporter;
//importer.isReadable = true;
importer.textureType = TextureImporterType.Sprite;
importer.spriteImportMode = SpriteImportMode.Multiple;
importer.mipmapEnabled = false;
importer.filterMode = FilterMode.Point;
importer.spritePivot = Vector2.down;
importer.textureCompression = TextureImporterCompression.Uncompressed;
var textureSettings = new TextureImporterSettings(); // need this stupid class because spriteExtrude and spriteMeshType aren't exposed on TextureImporter
importer.ReadTextureSettings(textureSettings);
textureSettings.spriteMeshType = SpriteMeshType.Tight;
textureSettings.spriteExtrude = 0;
importer.SetTextureSettings(textureSettings);
int minimumSpriteSize = 16;
int extrudeSize = 0;
Rect[] rects = InternalSpriteUtility.GenerateAutomaticSpriteRectangles(texture, minimumSpriteSize, extrudeSize);
var rectsList = new List<Rect>(rects);
rectsList = SortRects(rectsList, texture.width);
string filenameNoExtension = Path.GetFileNameWithoutExtension(path);
var metas = new List<SpriteMetaData>();
int rectNum = 0;
foreach (Rect rect in rectsList)
{
var meta = new SpriteMetaData();
meta.pivot = Vector2.down;
meta.alignment = (int)SpriteAlignment.BottomCenter;
meta.rect = rect;
meta.name = filenameNoExtension + "_" + rectNum++;
metas.Add(meta);
}
importer.spritesheet = metas.ToArray();
AssetDatabase.ImportAsset(path, ImportAssetOptions.ForceUpdate);
}
static List<Rect> SortRects(List<Rect> rects, float textureWidth)
{
List<Rect> list = new List<Rect>();
while (rects.Count > 0)
{
Rect rect = rects[rects.Count - 1];
Rect sweepRect = new Rect(0f, rect.yMin, textureWidth, rect.height);
List<Rect> list2 = RectSweep(rects, sweepRect);
if (list2.Count <= 0)
{
list.AddRange(rects);
break;
}
list.AddRange(list2);
}
return list;
}
static List<Rect> RectSweep(List<Rect> rects, Rect sweepRect)
{
List<Rect> result;
if (rects == null || rects.Count == 0)
{
result = new List<Rect>();
}
else
{
List<Rect> list = new List<Rect>();
foreach (Rect current in rects)
{
if (current.Overlaps(sweepRect))
{
list.Add(current);
}
}
foreach (Rect current2 in list)
{
rects.Remove(current2);
}
list.Sort((a, b) => a.x.CompareTo(b.x));
result = list;
}
return result;
}
}
@stephenlucerne
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Editing TextureImporter.spritesheet no longer works in Unity 2020+
I shared a code snippet here (https://forum.unity.com/threads/sprite-editor-automatic-slicing-by-script.320776/#post-9756150) that works in newer versions of unity.

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