Based on my knowledge, this sounds like a known issue related to texture rotation handling during runtime repacking. The problem you're describing with UV distortion when aspect ratios don't match (or aren't simply rotated versions of each other) is a specific edge case that can occur with rotated atlas regions.
Here are some things to try:
Disable rotation during atlas packing:
The most reliable solution is to export your atlas from Spine with rotation disabled. In the Spine Texture Packer settings, disable the Rotation option. This will prevent regions from being rotated in the atlas, which should eliminate the aspect ratio mismatch issue you're encountering during repacking.
Check your source atlas settings:
Since you mentioned this happens consistently for one specific part, verify that:
- The source texture for that region doesn't have
Non-Power of Two set to anything other than None in the Unity Texture import settings
- The atlas was exported from Spine with
Power of two enabled in the Pack Settings
Clear the repacking cache:
After performing repacking operations, try calling:
AtlasUtilities.ClearCache();
This clears any cached data that might be causing issues with subsequent repack operations.
Verify the region's original state:
Double-check that the problematic region appears correctly in your original (non-repacked) atlas and that the issue only appears after repacking. If it's already distorted in the source atlas, the problem lies with the initial export/import settings rather than the repacking process.
If disabling rotation during atlas export resolves the issue, that confirms this is related to how rotated regions are handled during runtime repacking.
