Graphic rendering bug of colored node (overlay disappears?)

[sfence]

Luanti version

luanti --version
Luanti 5.15.0 and 5.15.1 and master (73aba2e) (Linux)
Using LuaJIT 2.1.1767980792
Built by GCC 15.2
Running on Linux/6.18.9 x86_64
BUILD_TYPE=Release
RUN_IN_PLACE=0
USE_CURL=1
USE_GETTEXT=1
USE_SOUND=1
STATIC_SHAREDIR="/usr/share/luanti"
STATIC_LOCALEDIR="/usr/share/locale"

Operating system and version

Arch Linux

CPU model

No response

GPU model

AD104GL - RTX 4000 Ada Generation

Active renderer

opengl3 and ogles2

Summary

Graphic rendering problem on node defined here https://github.com/mt-mods/homedecor_modpack/blob/992739d532808b6e671a0a4a618f9ed5cb41bdcd/homedecor_lighting/init.lua#L273

simplescreenrecorder-2026-02-18_19.13.56.mp4

Steps to reproduce

Not sure, not reproduced in the test world

[Desour]

Those nodes use use_texture_alpha = "blend".
Have you tried disabling the transparency_sorting_group_by_buffers setting?

[sfence]

@Desour
Good tip, when I disable transparency_sorting_group_by_buffers problem disappears.
Enable, the problem is back.

[Desour]

Transparency sorting not fully working is to expected with this setting (it's a performance vs correctness tradeoff).

There have been discussion in the PR that introduced it #15115 already about making it not as extreme. At some point we should probably do something in that direction.

Anyways, in this case here, one could expect it work even with transparency_sorting_group_by_buffers on: The overlay tiles mesh buffer should be drawn after the underlying tiles' buffer.
But idk how being overlay tile is handled in transparency sorting right now, or if we use array textures for transparent faces yet.

[sfence]

In that case, should be transparency_sorting_group_by_buffers turned on by default?

[Desour]

As said, it's a tradeoff. And the current default chooses performance over correctness.