#2591 Corrupted canvas displays with osm2city buildings

[Colin Geniet]

When osm2city buildings are enabled, some elements on canvas displays are missing or blinking:

• Corrupted canvases (missing lines on HUD and radar display): https://postimg.cc/VSZxCjMD
• What it should look like: https://postimg.cc/5YHZq6S1

This is on branch next, compiled around 23/05/2021.
The problems typically appear after less than a minute in flight close to an area with buildings.
The issue doesn't appear without osm2city buildings. Other rendering settings seem to have no effect.
The issue doesn't seem to be specific to the aircraft or location: I reproduced it with both the JA-37 and MiG-21, at LFMT and BIKF.
I did not see anything log message which seemed relevant.

Attached:

• details of FG and GL versions
• rendering settings
• log file (same FG run as the pictures above)

[James Turner]

Interesting. Some things that migth help with this:

• is it the same behaviour with 2020.3.8 ? (it should be)
• which GPU are you trying on?
• In principle, OSm2CIty is the same as two existing features: modle based builds (eg, Paris had a lot) and random shader-based buildings. The source data is different but the way they are rendered is the same so ... yeah it's weird.

I'd suggest removing / breaking the buildings.eff Effect so that the shader based OSM2CIty buildings don't draw: this would then leave the 'model' buildings which are used for more complex shapes (shader buildings are used for cubes/cuboids). If disabling the effect fixes the issue, it's some interaction between the buildings shader/instancing and the Canvas. If that's not it, then ... it's something really exciting.

But if you previous used 'random buildings' this also uses the buildings effect, so, again, it should cause the same problems.

[Colin Geniet]

Good thing that you mentioned random buildings / model based buildings. After checking:

1. I do not have this issue with random / model buildings enabled
2. More importantly, I don't see random / model buildings at all

Regular scenery objects have no issue. It sure looks like something is messed up in building.eff.

On 2020.3.6, the issue doesn't occur, and I see random / model buildings correctly. So I would guess an issue related to / introduced by Compositor. I will see what I can do by tinkering with building.eff.

GPU is RX560X

/sim/rendering/gl-vendor: AMD
/sim/rendering/gl-renderer: AMD Radeon (TM) RX Graphics (POLARIS11, DRM 3.40.0, 5.12.6-gentoo, LLVM 11.1.0)
/sim/rendering/gl-version: 4.6 (Compatibility Profile) Mesa 21.0.3
/sim/rendering/gl-shading-language-version: 4.60

[James Turner]

@fgarlin any ideas from your side are welcome.

[Fernando García Liñán]

Wow, that's a really weird one. I can't think of anything on building.eff that might trigger such a specific error. Stuart significantly simplified building.eff not long ago too.

At first it looked like depth related issues, but the lines that have the sky as the background look fine. I honestly have no idea where to start with this one.

[legoboyvdlp]

This does look similar to the one on the A320-family that occurs whenever you change certain rendering settings (the top part of the canvas disappears, coupled with large slowdowns).