Re: [Caml-list] How to synchtonize swap buffers with vertical retrace in lablgk/lablgtk, or labgl/labltk,

[Sven LUTHER <luther@dpt-info.u-strasbg.fr>]

On Fri, May 04, 2001 at 02:30:28AM -0700, Peter Ronnquist wrote:
> 
> --- Sven LUTHER <luther@dpt-info.u-strasbg.fr> wrote:
> > On Thu, May 03, 2001 at 11:11:50AM -0700, Chris
> > Hecker wrote:
> > > 
> > > >I am looking for a way to synchronize swapbuffers
> > with
> > > >the vertical retrace using lablg and lablgtk or
> > labltk
> > > >for creating the window to draw the opengl
> > graphics
> > > >in.
> > > >Does anyone know if this is possible?
> > > 
> > > You usually have to do this through an extension. 
> > It's a windowing system issue (or at least, that's
> > how OpenGL thinks of it).  So, on windows there's a
> > SwapInterval extension, and I'm not sure about X,
> > but it's probably the same.
> > > 
> > > You'll need to write a thunk to the extension in C
> > to use it, because lablgl does not support
> > extensions yet.  I hope to fix this at some point
> > soon. 
> > 
> > Does X not do this by himself, at least if you use
> > hardware accelerated mesa
> > drivers (the dri version of them). Not sure though.
> 
> 
> I have looked into the examples that are provided with
> lablgl and lablgtk and comparared it with the C
> version of gears.c. You can notice a small disruption
> in the animation gears.ml and planet.ml (when the
> planet is closer and is displayed big on the screen).
> This is due to that the swap buffer is done when the
> monitors ray gun is in the middle of the graphics.
> 
> There are also some small and good tutorial examples
> that uses C and glx that does not have this problem.
> Here there is no disruption of the animation at all.
> I can provide you with the link to this webpage when I
> get access to the link.
> 
> It seems that it is up to the library that you use for
> handling the window for opengl. Appearantly gtk and tk
> does not do this syncronization.
> glut, glx do this and I am almost sure that sdl do
> that as well. 

mmm, ...

lablgl + lablgtk uses the gtkglarea library, if i am not wrong. Did you try
the gtkglarea examples for the same thing ? 

Also what openGL lib are you using, what X server, what OS, what graphic card
? All of this may have an impact on the openGL display. Also are you using
software rendreing or hardware ? try glxinfo to be sure.

Do you have an idea of what the C example you speak about do that is not done
by lablgl ? 

Or maybe it is just the garbage collector quicking in, and thus slowing the
display ?

Friendly,

Sven Luther


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