<html dir="ltr">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" id="owaParaStyle">P {margin-top:0;margin-bottom:0;}</style>
</head>
<body fpstyle="1" ocsi="0">
<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">
<div style="direction:ltr; font-family:Tahoma; color:#000000; font-size:10pt"><br>
Hi all,<br>
<br>
I'm normally using a powerful server for image processing, and then I look at the data by remote ssh with X forwarding. Recently I upgraded the linux OS on my laptop (to Ubuntu 18.04) and all sorts of programs stopped working this way, including 3dmod. It turned
out to be a much broader problem having to do with OpenGL. Indirect rendering, which is what we need, is turned off by default in newer versions of X. I assume others have encountered such trouble as well. Since it took quite some digging to find a solution
I'm posting it here.<br>
<br>
For those who boot into a command line interface with a black screen and start an X session manually, (e.g., startx -- :2) the fix is simple.
<br>
Edit the file /usr/bin/startx and change the line defaultclientargs="" to defaultclientargs="+iglx"<br>
+iglx allows indirect rendering by OpenGL applications.<br>
This is not relevant to most of us.<br>
<br>
For those who boot the computer and expect to see the graphical display right away it's a bit trickier. Ubuntu uses X or Wayland for the graphical interface, depending on the version. The solution I found is only for X, so we have to revert to that first. It's
done in two steps, as root:<br>
1) In the file /etc/gdm3/custom.conf, uncomment (erase the hash) the line #WaylandEnable=false. (In Ubuntu it should be enough to start GNOME in Xorg, which is one of the login options.)<br>
2) Create a new file /usr/share/X11/xorg.conf.d/50-iglx.conf:<br>
Section "ServerFlags" <br>
Option "AllowIndirectGLX" "on" <br>
Option "IndirectGLX" "on" <br>
EndSection <br>
Reboot and it should work. at your own risk, of course...<br>
Other distributions might put these files in different places.<br>
<br>
Here are some useful resources:<br>
https://www.visitusers.org/index.php?title=Re-enabling_INdirect_glx_on_your_X_server<br>
https://lists.freedesktop.org/archives/xorg/2016-May/058072.html<br>
https://askubuntu.com/questions/745135/how-to-enable-indirect-glx-contexts-iglx-in-ubuntu-14-04-lts-with-nvidia-gfx/747088<br>
<br>
There seems to be a similar issue with XQuartz on the Mac, which is addressed by reverting to the last version that worked.<br>
<br>
There was another instruction to add in the file /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf<br>
[SeatDefaults]<br>
# Dump core<br>
xserver-command=X -core +iglx<br>
but this didn't work for me.<br>
<br>
As for Wayland, typing Xwayland -h shows that the options include +iglx, but I wasn't able to find a config file for passing it startup options.<br>
<br>
A longer term solution seems to be VirtualGL or TurboVNC. Does anyone have those working with 3dem visualization software?<br>
<br>
regards,<br>
Michael<br>
</div>
</div>
</body>
</html>