Hello there.
First of all, I am sorry for my English, I am not a native speaker.
I spent a lot of time to find a solution to my problem and I'm not sure, that it exists.
As you can see on the attachment two spineboys. First one from Unity3D with Spine/Skeleton shader and the second one I have made in the Microsoft Paint.
Is it possible to make the opacity in Unity, as I made in Paint?
I know my problem not related to Spine, but maybe you can give any hints?
Thank you for your help. 
Hello. Achieving the desired effect is not trivial unfortunately, currently we have no shader or setup included which provides this out of the box.
I have recently replied to this similar thread:
Unity3D 에서 불투명한 스파인 리소스가 겹치는 문제
If you want to make this work, you have to ensure the following:
1) Draw order sorting inside the mesh needs to be changed to front-to-back (Spine uses back-to-front order to handle transparency correctly)
2) ZWrite needs to be enabled
3) ZTest needs to be enabled
4) Alpha Test needs to discard very agressively, everything below 1.0 opacity should be clipped. Otherwise you would receive strange border outline effects.
So currently this would require changing the draw order of a skeleton (code adaptation) and a special shader.
We do not recommend that you perform these steps yourself, since they are not simple.
We will potentially come up with a built-in feature that will provide the functionality in the future, however currently we are busy with some high-priority issues.
Could you let us know your use case? Then we might be able to suggest a suitable solution.
