Re: [GtkGLExt] Sharing display lists among a dynamic set of widgets [solved]

["Timothy M. Shead" <tshead k-3d com>]

Thierry Bernier wrote:

> I have a similar problem under MinGW (over XP) : when I reparent a 
> Widget containing a GtkGLExtended widget in its children tree, the 
> displqy lists are losts after the reparent. Every other GL call works, 
> but calling the lists draws nothing.

The solution for me was to create a GdkGLPixmap that matches the screen 
depth, generate a GdkGLContext for it, and use that as the shared list 
context for all of my views.  Using an offscreen pixmap solves the 
problem of how to create a hidden widget and where to put it.  A code 
snippet without error-handling and cleanup:

/** Returns a global GdkGLContext that can be used to share
    OpenGL display lists between multiple drawables with
    dynamic lifetimes */
GdkGLContext* get_share_list()
{
   static GdkGLContext* share_list = 0;

   if(!share_list)
     {
       GdkGLConfig* const config = gdk_gl_config_new_by_mode(
         static_cast<GdkGLConfigMode>(
           GDK_GL_MODE_RGBA |
           GDK_GL_MODE_DOUBLE |
           GDK_GL_MODE_DEPTH));

       GdkPixmap* const pixmap =
         gdk_pixmap_new(0, 8, 8, gdk_gl_config_get_depth(config));

       GdkGLPixmap* const glpixmap =
         gdk_pixmap_set_gl_capability(pixmap, config, 0);

       share_list = gdk_gl_context_new(
         gdk_pixmap_get_gl_drawable(pixmap), 0, true, GDK_GL_RGBA_TYPE);
    }

  return share_list;
}

> I will post a bug, if you think this is really one.

I'd check to see what reparenting is doing, first.  Since GLX context is 
tied closely to individual drawables, it wouldn't surprise me to see 
that things stop working if the drawable changes, which I assume is 
happening when you reparent.

Cheers,
Tim