Stained glass block displays rendered aint rendered inside each other

[crazjj]

Bug Description

This bug even is in vanilla (i tested it in vanilla, my default client side fabric modpack, fabric+sodium only) and happens with translucent stained blocks for block displays... E.g. stained glass but also stuff like nether portal
Other blocks work the as expected in block displays

Nothing is changed between these screenshots except player location:

Reproduction Steps

Summon different sized block displays e.g. of stained glass and then of a normal block inside each other

Log File

latest.log

Crash Report

crash-2025-11-19_22.25.09-client.txt

[douira]

This bug happens because entity quads are sorted by distance, which can result in incorrect sorting when the quads are very different sizes and appropriately arranged.

Something like this happens, just the other way around. (the small quads' centers are closer to the camera than the big quads'

Since these entities are not terrain, we don't sort them with our terrain translucency sorting system. Potential to the entity translucency sorting problem include

• some variant of OIT,
• efficiently performing some subset of the same approaches we use for terrain to entities,
• finding some better approximation of visual ordering that isn't sorting quad centroids by distance.

We've been aware of this issue for years, but this is a nice example to track it with. I'll mark this as an enhancement request with the goal of fixing a vanilla issue. If readers of this comment are interested in contributing ideas or implementations, please discuss in the dev-sodium channel on our discord server.

[douira]

Could you provide us with your test world or a set of commands with which we can reproduce it?

[crazjj]

i roughly get what you mean, thxx
heres a world link (1 week available, 10.9MB): https://limewire.com/d/FyeC9#N4qgHgGMNX (1.21.10, coords: -103, 70, -103)
im developing a paper plugin (closed source as of now) so best way is providing a world

[douira]

I have found a pretty good metric that sorts display entities with large quads better than sorting them by distance. However, it's much slower because it calculates the closest point on a rectangle to the camera, instead of just the centroid. I'm not sure if or how we'd want to use this by default because it does run in the critical path and slows things down.

You can try it out with the build generated by this GH Action run or build the branch yourself.

(the world came without cheat permission so it got dark over time)