[R-pkg-devel] Catching console messages from libGL

[Duncan Murdoch]

On 17/02/2020 2:56 p.m., Duncan Murdoch wrote:
> I'm working on the initialization code for rgl, especially for the case
> when it is running remotely and the user is connecting using X11.
> 
> On some machines, this fails:  I now understand that's because the local
> machine needs to enable "indirect GLX" (IGLX) for it to succeed, and by
> default most current machines have IGLX disabled.  (It can be a security
> risk to enable it.)
> 
> Failure looks like this (with the current CRAN version of rgl 0.100.47,
> and the remote system running Ubuntu, my local system running MacOS):
> 
>   > library(rgl)
>   > open3d()
> libGL error: No matching fbConfigs or visuals found
> libGL error: failed to load driver: swrast
> X Error of failed request:  GLXBadContext
>     Major opcode of failed request:  149 (GLX)
>     Minor opcode of failed request:  6 (X_GLXIsDirect)
>     Serial number of failed request:  42
>     Current serial number in output stream:  41
> 
> I end up booted right out of R.  I now know how to fix that, and will
> upload an update to CRAN in due course.
> 
> On MacOS I can enable IGLX by running
> 
>     defaults write org.macosforge.xquartz.X11 enable_iglx -bool true
> 
> and restarting XQuartz.  When I do that, I see this (same setup as before):
> 
>   > library(rgl)
>   > open3d()
> libGL error: No matching fbConfigs or visuals found
> libGL error: failed to load driver: swrast
> glX
>     1
> 
> Now I want to suppress those two libGL messages, and I'm having trouble
> figuring out how to do it.  If I redirect stderr when I start R, they
> are redirected:  but if I do it after starting R, they aren't:
> 
>   > library(rgl)
>   > capture.output(open3d(), type = "message")
> libGL error: No matching fbConfigs or visuals found
> libGL error: failed to load driver: swrast
> glX
>     1
> character(0)
> 
> (capture.output with type = "output" gets c("glX", "1"), but leaves the
> libGL messages printing to the console.  sink() behaves similarly.)
> 
> So how do I capture stderr (or, off topic here, how do I get libGL to be
> quiet)?
> 

A little bit of progress.  After reading the Mesa 3d source, I can see 
that setting environment variable

  LIBGL_DEBUG=quiet

will suppress the first message.  Unfortunately, the second message is 
seen as "critical", and it can't be suppressed.

Duncan Murdoch