[GRASS-dev] Re: [GRASS-user] [bug #3041] nviz max resolution ppm image dump

[Glynn Clements]

Hamish wrote:

> > > With off-screen rendering disabled, I get good results with either
> > > of the above var_i calculations.
> > 
> > The off-screen rendering draws to the back-buffer, GS_write_zoom()
> > dumps the front buffer. Also, Create_OS_Ctx() hides the Togl canvas
> > (presumably to prevent expose events from trashing the OpenGL state
> > during off-screen rendering), so it probably isn't usable for
> > rendering.
> > 
> > Does this help?
> > 
> > diff -u -r2.6 do_zoom.c
> > --- visualization/nviz/src/do_zoom.c	9 Jul 2006 08:58:40 -0000	2.6
> > +++ visualization/nviz/src/do_zoom.c	31 Aug 2006 12:58:16 -0000
> > @@ -325,6 +325,9 @@
> >      }
> >  #endif
> >  
> > +    if (!pbuffer && !glxpixmap)
> > +	    return 1;
> > +
> >      /* hide togl canvas before init_ctx 
> >       * This prevents bindings from re-initializing
> >       * togl */
> 
> Nope. No change.

Did you try with GRASS_NO_GLX_{PBUFFERS,PIXMAPS} set?

With those set, and the above patch, Create_OS_Ctx() should
essentially be a no-op.

> Does max res PPM dump work for anybody? (ie is it a platform dependent
> thing)
> 
> Shall we disable offscreen rendering for the 6.2 release branch in case
> it doesn't get fixed in time for release?

It should suffice to ensure that it can be disabled at run time.

-- 
Glynn Clements <glynn at gclements.plus.com>