Only two ReflectionProbes are visible per mesh in GLES2

[zoiba]

Godot 3.2

verified on PC Linux and Oculus Quest

I'm using GLES2, I've set multiple reflection probes for covering the various rooms in a building, only the first two probes works.

Hide all the probes and the show them by clicking in a different sequence, only the first two you made visible will work.

testcase_reflection_probe.zip

[clayjohn]

Does the building happen to be one large mesh? Only two probes can be used per mesh.

[zoiba]

yes it does, large meshes are involved in building design. haven't found such limitation written on the documentation, thank you for the information.

[clayjohn]

Oops. Looks like I misunderstood what you needed.

Only two probes can be visible at a single overlapping point per-mesh. However, you can have more per-mesh as long as they don't overlap. The renderer should select the closest two to use as you move around the building. It works correctly in GLES3.

[zoiba]

I reworked the test case project so to don't have overlapping reflection probes. If I unhide the first probe it works fine. The second probe works but it seems the "enable interior" turns on and off depending form camera orientation. The third and fourth probes simply don't work. If I Unhide the fifth probe Godot freezes immediately or after moving the camera.
Here the test case updated:
testcase_reflection_probe.zip

[KoBeWi]

Can anyone still reproduce this bug in Godot 3.2.3 or any later release?

[clktmr]

I can reproduce this bug in 3.3.4. Behaviour is exactly as OP has written. A single probe works fine. Two probes cause flickering of ambient light depending on camera angle. A third and fourth probe don't render at all. I played around with the reflection settings in Project/Render Quality, but couldn't see any difference. Only happens with the GLES2 backend, GLES3 works fine.

[KoBeWi]

Can you also check 3.4 beta?

[clktmr]

I have reproduced this with the current beta6. I've also attached my test scene.

I noticed one more thing: The reflection probes seem to get rendered correctly, as you can see by moving the MirrorSphere node around. The renderer only seems to fail selecting the correct probe for the mesh and blending between them seems to be broken in general.
GLES2-Reflections-TestScene.zip

[clktmr]

@zoiba also mentioned the engine freezing. I can reproduce this whenever there are more than two reflection probes with update_mode = UPDATE_ALWAYS.

[clktmr]

I took a look into this myself and gladly there was a simple fix for the flickering. I also found that there is indeed a limit of two refprobes per mesh in GLES2 as stated in rasterizer_scene_gles2.cpp:1079 which I added to the docs:

			rpsize = MIN(rpsize, 2); //more than 2 per object are not supported, this keeps it stable

However, the MR doesn't solve the freeze issue and there might still be issues if the refprobes are very close to each other.

[akien-mga]

Fixed by #53740.