[Solved] Slicing a Sprite through script on Importing

Hey all,

I've written some script that slices a sprite into equal regions like a grid according to a region Width and Height property. When I updated Unity to 2019.2, this script stopped working properly. This script is accessed in an editor window I built that allows me to choose a png file through a file browser and import it.

If I import an image that isn't a Power of Two, the image is resized to the nearest Power of Two automatically, and then the slicing gets messed up. For example, If I import an image thats 160x48 and attempt to slice it into chunks of 16x16, I expect 30 slices (10x3). However, the image actually comes in at 128x64 and that results in 24 slices (8x4).

Here's the script:

Code (CSharp):

1. public static void SliceSprite(string texturePath, int sizeX, int sizeY) {
2.     TextureImporter textureImporter = AssetImporter.GetAtPath(texturePath) as TextureImporter;
3.  
4.     if (textureImporter == null) {
5.         return;
6.     }
7.  
8.     textureImporter.textureType = TextureImporterType.Sprite;
9.     textureImporter.spriteImportMode = SpriteImportMode.Multiple;
10.     textureImporter.spritePixelsPerUnit = GameProperties.PixelsPerUnit;
11.     textureImporter.filterMode = FilterMode.Point;
12.     textureImporter.wrapMode = TextureWrapMode.Clamp;
13.     textureImporter.maxTextureSize = 2048;
14.     textureImporter.textureCompression = TextureImporterCompression.Uncompressed;
15.     textureImporter.crunchedCompression = false;
16.     textureImporter.compressionQuality = 100;
17.     textureImporter.isReadable = true;
18.     textureImporter.textureShape = TextureImporterShape.Texture2D;
19.     textureImporter.npotScale = TextureImporterNPOTScale.None;
20.  
21.     AssetDatabase.ImportAsset(texturePath, ImportAssetOptions.ForceUpdate);
22.  
23.     Texture2D sourceTexture = (Texture2D) AssetDatabase.LoadAssetAtPath(texturePath, typeof(Texture2D));
24.  
25.     Debug.Log(sourceTexture.width);
26.     Debug.Log(sourceTexture.height);
27.  
28.     List<SpriteMetaData> spriteMetaDatas = new List<SpriteMetaData>();
29.     int frameNumber = 0;
30.     for (int j = sourceTexture.height; j > 0; j -= sizeY) {
31.         for (int i = 0; i < sourceTexture.width; i += sizeX) {
32.             SpriteMetaData spriteMetaData = new SpriteMetaData {
33.                 name = sourceTexture.name + "_" + frameNumber,
34.                 rect = new Rect(i, j - sizeY, sizeX, sizeY),
35.                 alignment = 0,
36.                 pivot = new Vector2(0f, 0f)
37.             };
38.  
39.             spriteMetaDatas.Add(spriteMetaData);
40.             frameNumber++;
41.         }
42.     }
43.  
44.     Debug.Log(spriteMetaDatas.Count);
45.     textureImporter.spritesheet = spriteMetaDatas.ToArray();
46.     AssetDatabase.ImportAsset(texturePath, ImportAssetOptions.ForceUpdate);
47. }

This code will Log the correct width and height, but won't slice the image. The second Log of spriteMetaDatas.Count will report the correct number of slices.

If I remove Line 21, the Logs will report the wrong image size (resized to the nearest Power of Two), and the sprite will be sliced but incorrectly.


How do I fix it so that I can slice with the correct Dimensions?

 

Thanks to some help on the GDL Discord Unity-Dev channel, I got the solution.

I added:

EditorUtility.SetDirty(textureImporter);

After Line 21 where the Asset was imported with the first set of settings