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No Anti-aliasing on Linux Hades Canyon NUC

Graphics issues like: bad framerates, weird colors, OpenGL errors etc. Bad graphics ar usually the result of bad graphics cards or drivers.
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No Anti-aliasing on Linux Hades Canyon NUC

Postby genosensor » Mon Apr 15, 2019 7:31 am

I'm running flightgear on an Intel Hades Canyon NUC (NUC8i7hvk).
Debian Stretch
flightgear 1:2018:3.2+dfsg-2+b1 amd64
mesa components are versions 18.2 / 18.3 / 18.4
Linux kernel 5.0.7

The good news is that I'm getting 40-60hz frame rates with high quality settings out of a box a bit larger than an old VHS video tape.
The bad news is that I cannot enable any form of anti-aliasing.
When are try, the result is:

Code: Select all
Using default download dir: Path "/home/brent/.fgfs"
read-allowed path not found:Path "/home/brent/.fgfs/AI"
read-allowed path not found:Path "/home/brent/.fgfs/Liveries"
Using TerraSync dir: Path "/home/brent/.fgfs/TerraSync"
EmbeddedResourceManager: selected locale 'en_US'
Using stock OSG implementation of GraphicsWindow
StatsHandler::StatsHandler() Setting up GL2 compatible shaders
initializing cloud layers
Error: Not able to create requested visual.

getDefaultWindow: failed to create GraphicsContext
Error: Not able to create requested visual.

getDefaultWindow: failed to create GraphicsContext
CameraGroup::buildGUICamera: failed to build a window
Enabling ATI/AMD viewport hack
Configuration State
============= =====
aircraft-dir = "/usr/share/games/flightgear/Aircraft/c172p"
fghome-dir = "Path "/home/brent/.fgfs""
download-dir = "/home/brent/.fgfs"
terrasync-dir = "/home/brent/.fgfs/TerraSync"
aircraft-search-paths =
   
scenery-search-paths =
   /home/brent/.fgfs/TerraSync
   /usr/share/games/flightgear/Scenery
Segmentation fault


This occurs immediately upon startup of fgfs.

Note that anti-aliasing works fine on the same system with X-Plane 11.
Is there something fundamentally different about how X-Plane does anti-aliasing vs. flightgear?

Is this a known issue with the Linux open-source amdgpu driver under Gallium?
Is there anyone else running flightgear on the Intel NUC8i7hvk?
Should I file a bug report?

Thanks!
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Re: No Anti-aliasing on Linux Hades Canyon NUC

Postby Thorsten » Mon Apr 15, 2019 7:45 am

Is there something fundamentally different about how X-Plane does anti-aliasing vs. flightgear?


Yes - to my knowledge X-Plane doesn't use OpenSceneGraph to organize rendering.
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Re: No Anti-aliasing on Linux Hades Canyon NUC

Postby Icecode GL » Mon Apr 15, 2019 12:46 pm

Is there something fundamentally different about how X-Plane does anti-aliasing vs. flightgear?


X-Plane uses a deferred renderer and probably does antialiasing in software (FXAA or similar). FG only supports MSAA hardware antialiasing, which isn't supported by your driver (hence the segfault because the GraphicsContext couldn't be created).

You could try installing a better driver if it's available. Your discrete GPU is a Radeon RX Vega M, which is relatively new, so you might be out of luck finding proper drivers for it under Linux. It's just a matter of investigating a bit. :)
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Re: No Anti-aliasing on Linux Hades Canyon NUC

Postby genosensor » Tue Apr 16, 2019 2:43 am

Thanks, Icecode, for this explanation. My websearches were leading me to believe it must be a driver issue.
However...
Won't flightgear need to use an AA technique like FXAA to antialias its new deferred "Rembrandt" renderer?
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Re: No Anti-aliasing on Linux Hades Canyon NUC

Postby V12 » Tue Apr 16, 2019 8:54 am

Rembrandt is not new, but obsolete. There is not further development.
Fly high, fly fast - fly Concorde !
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Re: No Anti-aliasing on Linux Hades Canyon NUC

Postby Thorsten » Tue Apr 16, 2019 11:02 am

Won't flightgear need to use an AA technique like FXAA to antialias its new deferred "Rembrandt" renderer?


Actually, if you don't mind text being AAd a bit, you can (dependent on driver) ask your GPU directly to AA the output - that works independent from how FG renders anything - that works with Rembrandt as well.

Otherwise, yes, there's been no development for Rembrandt for a while, and it'll probably discontinued as soon as ALS 2.0 provides similar functionality.
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Re: No Anti-aliasing on Linux Hades Canyon NUC

Postby genosensor » Sat Apr 20, 2019 6:13 pm

I discovered that Xorg X11 server packages were being held back. I had intended to move from Debian stretch to "testing" (buster), but the X11 core packages did not get upgraded. Fixed this with an apt dist-upgrade and viola, anti-aliasing works!

With ALS and almost all the eye-candy enabled, I'm seeing frame rates ranging from 35hz over urban areas to >70hz when flying over water.
The average is in the mid 40's, which is fine by me.
However, if I turn, especially when flying low over urban areas, sometimes the sim will hang for a few hundred ms while it renders the new scenery.
Short of turning off all the eye candy, is there any way to mitigate this? Or, is this "normal"?

Note that I was seeing transient vsync related artifacts until I set the environment variable:

vblank_mode=3

It seems the amdgpu driver reports it supports WGL_EXT_swap_control yet actually exports glXSwapIntervalSGI
see: https://www.khronos.org/opengl/wiki/Swap_Interval
X-plane 11 somehow figures this out anyway, outputting a warning about it, then reverting to the SGI call.

A few scenery files related to rendering pylons were missing. Had to find them on the web.
They were:
Models/Power/generic_pylon_*

One last little niggle...
The joystick inputs are noisy. Is there any provision for low-pass filtering on them?
Again, X-plane seems to filter out the joystick noise quite well.

I'm a software engineer, not a pilot, but, nonetheless, my impression is that flightgear is more realistic in modeling flight dynamics than X-plane.
X-plane seems ridiculously forgiving of stalls and hard landings. And, it will let you taxi through other aircraft!
But, X-plane's rendering is smoother and its eye candy is superior.
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Re: No Anti-aliasing on Linux Hades Canyon NUC

Postby Richard » Wed Apr 24, 2019 2:10 pm

genosensor wrote in Sat Apr 20, 2019 6:13 pm:...
However, if I turn, especially when flying low over urban areas, sometimes the sim will hang for a few hundred ms while it renders the new scenery.


This is quite possibly a delay related to the way that the model textures are loaded[1].

In 2019.1 there is my new DDS texture cache that improves loading speed and significantly reduces display pauses. However at the moment there are still issues with this and I consider it still to be in beta. Hopefully the issues will be resolved soon.

There are other delays that can cause what I call a display pause, such as random vegetation - however these tend to be smaller (on my system).

------
[1] for those technically minded the problem is that mostly the formats we use for textures do not contain mipmaps and have to be generated before a model can be drawn. This happens usually in the rendering thread.
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Re: No Anti-aliasing on Linux Hades Canyon NUC

Postby genosensor » Wed Apr 24, 2019 5:11 pm

Great! I look forward to playing with this.
I've noticed little hiccups due vegetation, but these are slight on my system as well.
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