Hello there!

Im trying to use Depth of Field Volume effect on a 3D scene with a character using URP/Spine/SkeletonLit shader and an enviroment using URP/Spine/Sprite shader.

First of all I needed to enable Write to Depth in both shaders. In Sprite shader I enabled it in material, in SkeletonLit shader I changed _ZWriteOff_ to ZWriteOnin code.

To ensure proper draw order I used Z Spacing parameter in Advanced settings of SkeletonAnimation component (changed it to -0.001).

Depth of Field only affects opaque queue range (0 through 2500) so I needed to modify URP/Spine/SkeletonLit shader render queue (changed tag to "Queue"="AlphaTest").

Now depth of field is working correctly, but some parts of characters are still interpreted as not transparent.

To fix that I added alpha clipping in fragment shader to discard pixels that are below alpha cutoff value defined in material.

clip((tex.a) - _ACutoff);

This seems to fix issue with writing correct data to Z.

Sadly there is still an issue with drawing a skeleton itself. You can see that drawing another part of skeleton does not apply correct color on edges where transparency should blend two parts of skeleton seamlesly. Instead we can see the background in the area where edge is transparent.

I could increase alpha cliping value, but this also result in very sharp edges around skeleton, and does not look good.

It seems like MeshRenderer is drawing all parts using materials from list, but does not preserve order.
I made a quick test where I modify material render queue in SkeletonRenderer to force drawing order.

for (var i = 0; i < meshRenderer.sharedMaterials.Length; i++)
{
meshRenderer.materials[i].renderQueue -= i;
}

This seems to solve issue but is of course highly uneffective due to cration of multiple materials. Sadly sorting order cannot be set by PropertyBlock.

Do you have any ideas how to make it work? Is there some other way to preserve proper draw order in skeleton when using AlphaTest render queue in shader?

Spine package version: spine-unity-4.1-2023-06-27.unitypackage
Unity version: 2021.3.22f1