Unity Batch Sprite Slicer

BatchSpriteSlicer.cs

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

// Put this script in the Assets/Editor folder
namespace MaruEditor.Sprites {
    // Select a bunch of sprites, and slice them all at once
    public class BatchSpriteSlicer : EditorWindow {
        [MenuItem("Maru/Slice Selected Sprites")]
        static void Init() {
            var window = CreateInstance<BatchSpriteSlicer>();
            window.Show();
        }

        private static Vector2Int lastSize;

        private Rect buttonRect;
        private Vector2Int sliceSize;
        private bool sliceClicked;
        private bool cancelClicked;
        
        void OnGUI() {
            if (sliceSize == Vector2Int.zero) {
                sliceSize = lastSize;
            }
            sliceSize = EditorGUILayout.Vector2IntField("Slice Size", sliceSize);
            lastSize = sliceSize;
            sliceClicked = GUILayout.Button("Slice");
            cancelClicked = GUILayout.Button("Cancel");
            if (sliceClicked) {
                if (sliceSize.x == 0 || sliceSize.y == 0) {
                    Debug.LogError("Must set Slice Size to non-zero values");
                    return;
                }

                SliceSprites();
                Debug.Log("Done Slicing!");
                Close();
            }

            if (cancelClicked) {
                Close();
            }
        }

        // adapted from https://answers.unity.com/questions/1113025/batch-operation-to-slice-sprites-in-editor.html
        void SliceSprites() {
            foreach (var si in Selection.objects) {
                var tex = si as Texture2D;
                var path = AssetDatabase.GetAssetPath(tex);
                var ti = AssetImporter.GetAtPath(path) as TextureImporter;
                if (ReferenceEquals(ti, null)) {
                    continue;
                }
                ti.isReadable = true;
                ti.spriteImportMode = SpriteImportMode.Multiple;
                var newData = new List<SpriteMetaData>();
                for (var i = 0; i < tex.width; i += sliceSize.x) {
                    for (var j = tex.height; j > 0; j -= sliceSize.y) {
                        var smd = new SpriteMetaData {
                            pivot = new Vector2(0.5f, 0.5f),
                            alignment = 9,
                            name = tex.name + "_" + newData.Count,
                            rect = new Rect(i, j - sliceSize.y, sliceSize.x, sliceSize.y),
                        };
                        newData.Add(smd);
                    }
                }

                ti.spritesheet = newData.ToArray();
                AssetDatabase.ImportAsset(path, ImportAssetOptions.ForceUpdate);
            }
        }
        
    }
}