[Bf-committers] WITH_HEADLESS and OpenGL

[Carroll, Michael R]

Great, thank you for the feedback Campbell. I'll be taking a closer look at the first two options.


-MichaelC

-----Original Message-----
From: Campbell Barton [mailto:ideasman42 at gmail.com] 
Sent: Thursday, December 11, 2014 4:16 PM
To: Carroll, Michael R
Cc: bf-committers at blender.org
Subject: Re: WITH_HEADLESS and OpenGL

On Thu, Dec 11, 2014 at 11:26 PM, Carroll, Michael R <michael.r.carroll at intel.com> wrote:
> Hello BF-Committers,
>
>
>
> Does building Blender WITH_HEADLESS require linkage with OpenGL?

Currently yes, however it could be changed.

With headless builds (and in background mode) OpenGL arent called, there are a few possible workaround.

- Use mesa software OpenGL (we use this for blender-softwaregl on Linux), ... Not a real solution, but at least you don't need to install libs on the operating system.

- Stub-out OpenGL and link to a dummy library.
... No heavy dependencies, but takes some effort to setup. It could be preloaded or static link.

- Omit all GL calls from WITH_HEADLESS builds, ... the most correct solution, but likely disruptive to the current code-base. maybe interesting to try, but likely to add a lot if #ifdef's. Since this is a build option (not even included in official builds), its not such an attractive prospect to insert 100's of ifdef's all over the code.

Longer term we might move drawing code into our own GPU module, IIRC Jason Wilkins work went some way towards this, in that case its probably  less trouble to stub out the drawing calls and remove the OpenGL dependency.


> I have read the renderer doesn’t leverage OpenGL at all. I see the 
> window
> manager/X11 features have been disabled in the WITH_HEADLESS source.
> However, I attempt to compile (using CMAKE) without any of the
> WITH_GL_PROFILE* options and bump into OpenGL related compiler errors. 
> They start with the second editors/ object:
>
>
>
> [  5%] Building C object
> source/blender/editors/armature/CMakeFiles/bf_editor_armature.dir/edit
> armature_sketch.c.o
>
> /blender/blender/source/blender/editors/armature/editarmature_sketch.c:441:26:
> error: unknown type name ‘GLUquadric’
>
> static void sk_drawPoint(GLUquadric *quad, SK_Point *pt, float size)
>
>
>
> Would OpenGL have to be shimmed out or is there a build toggle to 
> remove OpenGL?
>
> Many sources in the editors/ folders appear to use OpenGL… can these 
> specifically be removed from a WITH_HEADLESS build?
>
>
>
> I have been lurking on the mail list reading related conversations… 
> starting with the March’11 thread with Campbell, Brecht, and Pete. 
> Campbell suggested that adding the WITH_HEADLESS feature could negate 
> the requirement for OpenGL. I have seen a lot of checkins to support 
> WITH_HEADLESS but those same diffs don’t appear to remove OpenGL from the build flow.
>
>
>
> I’m looking to run Blender for performance analysis on many different 
> platforms. Eliminating any GUI is a requirement. Removing OpenGL would 
> also be extremely helpful.
>
>
>
> Thank you,
>
> -MichaelC
>
>



--
- Campbell