How to override geometry of a procedurally generated sprite in Editor Mode

HI,

I'm trying to develop a 2D tile tool custom editor window and I want it to be able to create non square sprites.

like this:

||

|| || (Imagine each set of two bars is a tile that after gets merged into a single sprite) ||||||

In editor mode I create several tiles from from sprites that I have in the assets folder and then merge them together into a single new texture by copying the pixels from the originals texture. Then I create a sprite using that texture. But when I want to use overrideSpriteGeometry:

"sprite.OverrideGeometry (verts, tris);"

I get this error:

"Not allowed to override geometry on sprite 'MySprite'".

I'm not creating assets files for the texture nor the sprite. The code in general would be like this:

 Texture2D texture = new Texture2D(w,h);
 texture.setPixels(pixelArray);
 texture.apply();

 Sprite Sprite = Sprite.Create (texture , rect, pivot, pixelsPerUnit);
 
 sprite.overrideGeometry(vertices, triangles);

// Then add it to a GameObject

I have tried OnPostprocessSprites with a AssetPostprocessor subclass but it doesn't get called when creating a sprite like this.

¿How can I override the geometry of a sprite that was created this way?

     TextureImporter footprintTextureImporter = (TextureImporter) AssetImporter.GetAtPath(footprintTextureName);
     
     for (int s = 0; s < footprintTextureImporter.spritesheet.Length; ++s) {
     footprintTextureImporter.spritesheet[s].rect.height = footprintTextureImporter.spritesheet[s].rect.height + 3;
                     }