Flickering sky when running world from sdf file. about gz-sim

[Rick-v-E]

Hi all,

I am running into the same issue.

With shadows:

Without shadows, it is much better. However, still some flickering occurs:

I am also running it on a laptop without GPU:

$ LANG=C glxinfo -B | grep -i '\(direct rendering\|opengl\|profile\)'
direct rendering: Yes
    Preferred profile: core (0x1)
    Max core profile version: 4.6
    Max compat profile version: 4.6
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.2
OpenGL vendor string: Intel
OpenGL renderer string: Mesa Intel(R) Graphics (ADL GT2)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 23.0.4-0ubuntu1~22.04.1
OpenGL core profile shading language version string: 4.60
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL version string: 4.6 (Compatibility Profile) Mesa 23.0.4-0ubuntu1~22.04.1
OpenGL shading language version string: 4.60
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile
OpenGL ES profile version string: OpenGL ES 3.2 Mesa 23.0.4-0ubuntu1~22.04.1
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20

[azeey]

@iche033 is this due to the non-NVIDIA GPU?

[iche033]

I do remember seeing flickering sky issue on user laptops before. It could be a gpu / driver issue.

[frede791]

Ok thanks. I will see if this error happens when i run it using a GPU and report back.

[biagio-trimarchi]

Hi! I am coming here from a post I made on Gazebo Community.

This looks like the same problem I am facing. I wrote an SDF world with a sky and a directional light, and when I toggle the shadows the sky start flickering.

Here some information about my machine, as in the first post in this issue:

$ LANG=C lspci -nn | grep VGA
00:02.0 VGA compatible controller [0300]: Intel Corporation Alder Lake-P GT1 [UHD Graphics] [8086:46a3] (rev 0c)
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation Device [10de:28a0] (rev a1)

$ echo "$DISPLAY"
:0

$ LANG=C glxinfo -B | grep -i '\(direct rendering\|opengl\|profile\)'
direct rendering: Yes
    Preferred profile: core (0x1)
    Max core profile version: 4.6
    Max compat profile version: 4.6
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.2
OpenGL vendor string: Intel
OpenGL renderer string: Mesa Intel(R) Graphics (ADL GT2)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 23.0.4-0ubuntu1~22.04.1
OpenGL core profile shading language version string: 4.60
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL version string: 4.6 (Compatibility Profile) Mesa 23.0.4-0ubuntu1~22.04.1
OpenGL shading language version string: 4.60
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile
OpenGL ES profile version string: OpenGL ES 3.2 Mesa 23.0.4-0ubuntu1~22.04.1
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20

$ ps aux | grep Xorg
biagio     26878  0.0  0.0   9212  2560 pts/6    R+   20:09   0:00 grep --color=auto Xorg

$ sudo env LANG=C X -version

X.Org X Server 1.21.1.4
X Protocol Version 11, Revision 0
Current Operating System: Linux athena 6.2.0-39-generic #40~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Thu Nov 16 10:53:04 UTC 2 x86_64
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-6.2.0-39-generic root=UUID=bb022743-038b-409c-b381-21e78caa4017 ro quiet splash vt.handoff=7
xorg-server 2:21.1.4-2ubuntu1.7~22.04.5 (For technical support please see http://www.ubuntu.com/support) 
Current version of pixman: 0.40.0

[frede791]

Yes. So I was able to confirm that if I use a GPU then the flickering does not appear. See Image below.

[iche033]

I wrote an SDF world with a sky and a directional light, and when I toggle the shadows the sky start flickering.

oh sounds like the shadows (or the light) is causing the sky to flicker? One workaround would be to disable shadows for the directional light.

[frede791]

Yes this worked! If I disable the shadows for my sun and enable them for the scene only, I can run the sky.

[frede791]

@iche033 Is having both sets of shadows enabled still a bug?

[iche033]

Is having both sets of shadows enabled still a bug?

I haven't seen any movement on this so I assume it's still an issue.

[ghfue]

I see this issue running on multiple computers with an Nvidia GPU. Disabling cast shadows from the sun also fixes the issue for me.