bzflag is not working properly with 3+ monitors

[jose1711]

with 3 monitor setup bzflag window flashes and mouse cursor jumps making it really hard to even exit the game. this video illustrates the issue: https://www.youtube.com/watch?v=HTjVPt2RnXs. once all but one displays are disabled (using xrandr) bzflag can be played.

[blast007]

What Linux distribution and distribution version are you running? What video card and driver/version? Do all three of your screens have the same resolution? Does it also happen with two displays or just with three?

[jose1711]

What Linux distribution and distribution version are you running?

Arch Linux current

What video card and driver/version?

Nvidia GeForce GTX 750Ti, proprietary driver 430.26

Do all three of your screens have the same resolution?

no.

$ xrandr | grep connected
VGA-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 509mm x 286mm
DVI-D-0 connected primary 1280x1024+1920+0 (normal left inverted right x axis y axis) 376mm x 301mm
HDMI-0 connected 1440x900+3200+0 (normal left inverted right x axis y axis) 428mm x 255mm

Does it also happen with two displays or just with three?

I disabled VGA-0 output reducing number of displays to 2 and the issue disappeared.

[macsforme]

I have a three-monitor setup as well, comprised of (from left to right) a 1080p monitor in portrait mode, and then two 1080p monitors in landscape mode. In Ubuntu Linux 19.04, when I use the BZFlag version from the snap repository, which uses SDL 1.2 (probably the same as what is in the repositories for other distributions), the window is spread across all three monitors and is very zoomed in with a large portion of the window missing. When I toggle to windowed mode, display options shows this:

When I compile from source against SDL 2, the window occupies my main monitor only, with the proper resolution and layout, and display options shows this:

This leads me to wonder if this is an SDL 1.2 issue.

@jose1711, can you try compiling the game from source using SDL 2, and tell us if you have a different result? ./configure -help shows the options needed to do that.

[jose1711]

please note that it's already compiled with SDL 2 on my system:

$ ldd `which bzflag` | grep -i sdl
	libSDL2-2.0.so.0 => /usr/lib/libSDL2-2.0.so.0 (0x00007f6fff4b3000)

[macsforme]

@jose1711, would you please compile and run this source file and post the output? This will give us more specific information about your monitor setup that could help us move forward.

listResolutions.cpp.zip

[jose1711]

Display 0:
	[Current] 1280 x 1024 @ 60Hz (370546692)
	[0] 1280 x 1024 @ 75Hz (370546692)
	[1] 1280 x 1024 @ 60Hz (370546692)
	[2] 1280 x 960 @ 60Hz (370546692)
	[3] 1152 x 864 @ 75Hz (370546692)
	[4] 1024 x 768 @ 75Hz (370546692)
	[5] 1024 x 768 @ 70Hz (370546692)
	[6] 1024 x 768 @ 60Hz (370546692)
	[7] 800 x 600 @ 75Hz (370546692)
	[8] 800 x 600 @ 72Hz (370546692)
	[9] 800 x 600 @ 60Hz (370546692)
	[10] 800 x 600 @ 56Hz (370546692)
	[11] 640 x 480 @ 75Hz (370546692)
	[12] 640 x 480 @ 73Hz (370546692)
	[13] 640 x 480 @ 60Hz (370546692)
Display 1:
	[Current] 1920 x 1080 @ 60Hz (370546692)
	[0] 1920 x 1080 @ 60Hz (370546692)
	[1] 1680 x 1050 @ 60Hz (370546692)
	[2] 1600 x 900 @ 60Hz (370546692)
	[3] 1440 x 900 @ 60Hz (370546692)
	[4] 1280 x 1024 @ 60Hz (370546692)
	[5] 1280 x 720 @ 60Hz (370546692)
	[6] 1024 x 768 @ 60Hz (370546692)
	[7] 800 x 600 @ 60Hz (370546692)
	[8] 640 x 480 @ 60Hz (370546692)
	Unable to get details for display mode 9 of display 1.

[macsforme]

It seems that SDL is reporting a certain number of resolutions, but it fails when attempting to get details for at least one of them. I would consider this to be an issue between SDL and your operating systems. I am not seeing any indication that this issue lies within our code.

[jose1711]

i think the problem might be in the code of listResolutions.cpp.
changing this line:
const auto numDisplayModes = SDL_GetNumDisplayModes(0);
to
const auto numDisplayModes = SDL_GetNumDisplayModes(i);
and recompiling stops error from appearing. the output then looks as follows:

Display 0:
	[Current] 1280 x 1024 @ 60Hz (370546692)
	[0] 1280 x 1024 @ 75Hz (370546692)
	[1] 1280 x 1024 @ 60Hz (370546692)
	[2] 1280 x 960 @ 60Hz (370546692)
	[3] 1152 x 864 @ 75Hz (370546692)
	[4] 1024 x 768 @ 75Hz (370546692)
	[5] 1024 x 768 @ 70Hz (370546692)
	[6] 1024 x 768 @ 60Hz (370546692)
	[7] 800 x 600 @ 75Hz (370546692)
	[8] 800 x 600 @ 72Hz (370546692)
	[9] 800 x 600 @ 60Hz (370546692)
	[10] 800 x 600 @ 56Hz (370546692)
	[11] 640 x 480 @ 75Hz (370546692)
	[12] 640 x 480 @ 73Hz (370546692)
	[13] 640 x 480 @ 60Hz (370546692)
Display 1:
	[Current] 1920 x 1080 @ 60Hz (370546692)
	[0] 1920 x 1080 @ 60Hz (370546692)
	[1] 1680 x 1050 @ 60Hz (370546692)
	[2] 1600 x 900 @ 60Hz (370546692)
	[3] 1440 x 900 @ 60Hz (370546692)
	[4] 1280 x 1024 @ 60Hz (370546692)
	[5] 1280 x 720 @ 60Hz (370546692)
	[6] 1024 x 768 @ 60Hz (370546692)
	[7] 800 x 600 @ 60Hz (370546692)
	[8] 640 x 480 @ 60Hz (370546692)
Display 2:
	[Current] 1440 x 900 @ 60Hz (370546692)
	[0] 1440 x 900 @ 75Hz (370546692)
	[1] 1440 x 900 @ 60Hz (370546692)
	[2] 1280 x 1024 @ 75Hz (370546692)
	[3] 1280 x 1024 @ 60Hz (370546692)
	[4] 1280 x 960 @ 60Hz (370546692)
	[5] 1152 x 864 @ 75Hz (370546692)
	[6] 1024 x 768 @ 75Hz (370546692)
	[7] 1024 x 768 @ 70Hz (370546692)
	[8] 1024 x 768 @ 60Hz (370546692)
	[9] 800 x 600 @ 75Hz (370546692)
	[10] 800 x 600 @ 72Hz (370546692)
	[11] 800 x 600 @ 60Hz (370546692)
	[12] 800 x 600 @ 56Hz (370546692)
	[13] 640 x 480 @ 75Hz (370546692)
	[14] 640 x 480 @ 73Hz (370546692)
	[15] 640 x 480 @ 60Hz (370546692)

[macsforme]

Ah, good catch. My monitors are all the same resolution (and probably have the same number of modes), so I didn’t catch that.

Can you launch in windowed mode with -window 1024x768 (or something like that), then select a resolution in Display Options, and then see if that makes it work the next time you launch the game normally?

[jose1711]

Running with -window 1024x768, then selecting this resolution in Display Options, my primary (center) monitor goes blank (black). When I switch to text console and kill the game process, the display is restored. It's really hard to terminate the process from virtual terminal as the mouse is constantly being grabbed.

[macsforme]

Running out of ideas on this. It reminds me of the issue with retina MacBooks, where SDL 2 was reporting resolutions that couldn't actually be set, so the screen just kept flashing as the game tried again and again to set the (incorrect) native resolution. Maybe we need to rework the window initialization so that it tries once, then just accepts whatever resolution it's actually given.

@jose1711, any way you can you try temporarily disabling the proprietary NVIDIA driver and see if the issue persists with the nouveau driver? I may be grasping at straws, but in my experience the proprietary NVIDIA driver can cause strange issues (in my case, certain output ports not working, night shift not working, garbled desktop wallpaper on wake from sleep, and intermittent failures to boot, to name a few).

Otherwise, since we can't reproduce the issue on other Linux three-monitor systems, depending on how much effort you're willing to put in to have this issue fixed, we may need you to run modified code to output some information about the window initialization so we can see where the discrepancy occurs.

[jose1711]

hey @macsforme i've tested with nouveau driver and the problem is still present. i am willing to provide more information about my system, try test builds, compile and run helper applications etc.

[atupone]

It's really hard to terminate the process from virtual terminal as the mouse is constantly being grabbed.

You can try confine mouse no in Option->Input