We have some custom shaders for our spine characters having issues with alpha not working properly in animations. In the spine editor, the image will disappear when alpha becomes 0, but when we import it into unity, it doesn't disappear.
After some digging, we found that the naming of the shader somehow affects how the shader works. (???)
Our custom shader was originally named "Custom/Spine/Spine-Character", which has the alpha issue.
If we rename it to "Custom/Spine/Skeleton-Character", the alpha works fine.
So we tried to renamed the default "Spine/Skeleton" shader to "Spine/Haha", and the alpha issue appeared again.
So... What's happening?
We are using spine-unity-3.8-2019-10-08, on Unity 2018.4.3
Spine assets exported with pre-multiplied alpha.