Bug 8896

Hi,

I have written a small programme using GTK+ and GtkGLExt. When "dri" is
disabled, my programme runs fine. But when "dri" is enabled, my programme
crashes with the following error message:

myprompt> ./test_glext --sync

[*** I got as far as glXMakeCurrent ***]
The program 'test_glext' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadValue (integer parameter out of range for operation)'.
  (Details: serial 266 error_code 2 request_code 128 minor_code 7)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

I originally suspected this could be a graphics driver problem. So I set out to
try my program out on both my systems. Here is what I found:

. First machine:
   Card: Intel 915 GM
   X Protocol Version 11, Revision 0, Release 7.0
      Build Operating System:Linux 2.6.12-1-686 i686
   Kernel:   2.6.18
   Processor: one Intel Pentium M processor 2.00GHz (32 bit)
   with Driver "i810" + Direct Rendering ENABLED   = X error
   with Driver "i810" + Direct Rendering DISABLED  = Works

. Second machine:
   Card: ATI Radeon 9200 PRO/SE (Rev 280)
   X Protocol Version 11, Revision 0, Release 7.0
      Build Operating System: Linux 2.6.16-1-vserver-amd64-k8 x86_64
   Kernel: 2.6.17-2-amd64
   Processor: two AMD Opteron Processor 250 (64 bit)
   with Driver "fglrx" + Direct Rendering ENABLED      = X error
   with Driver "ati" + Direct Rendering ENABLED        = X error
   with Driver "ati" + Direct Rendering DISABLED       = Works

So it then appeared as though the problem was with DRI. I started breaking down
my code to find exactly where the crash occurs and tracked it down to the 
function

   gdk_gl_drawable_gl_begin(gldrawable, glcontext)

I downloaded the code for GtkGLExt to find where within this function the crash
occurs. I tracked it down to the function

   glXMakeCurrent(xdisplay, glxpixmap, glxcontext)

So it would appear that the problem is not with GtkGLExt. Which brought me back
to suspecting a problem with "dri". I recently found on the DRI User Guide:

http://dri.sourceforge.net/doc/DRIuserguide.html

The following message:

11.2 GLX
...
GLXPixmap rendering is only supported for indirect rendering contexts. This is a
common OpenGL limitation. Attempting to use a direct rendering context with a
GLXPixmap will result in an X protocol error. 

This seems highly relevant to the bug I am experiencing so if someone could give
me details about this, I would greatly appreciate it.

Anyways, I pasted below the code which replicates the bug. Could someone help me
resolve this problem?

Thanks,
cbeau.

/* Test programme demonstrating the crash when "dri" is enabled */
#include <stdlib.h>
#include <gtk/gtk.h>
#include <gtk/gtkgl.h>
#include <gdk/x11/gdkglx.h>

int main(int argc, char **argv)
{
   GtkWidget *main_window, *image;
   GdkGLConfig *glconfig;
   GdkPixmap *pixmap;
   GdkGLPixmap *glpixmap;
   GdkGLContext *glcontext;
   GdkGLDrawable *gldrawable;
   GLXPixmap glxpixmap;
   GLXContext glxcontext;

   gtk_init(&argc,&argv);

   /* Allowing GtkGLExt to retreive its command line options */
   gdk_gl_init(&argc,&argv);

   /* Check if the OpenGL extension is supported. */
   if( gdk_gl_query_extension() == FALSE ) {
      g_print("OpenGL extension not supported\n");
      exit(1);
   }
   /* Create new top level window. */
   main_window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
   /* Set the main window's title */
   gtk_window_set_title(GTK_WINDOW(main_window), "Testing GdkGLExt");
   /* Add the destroy even to the main window */
   gtk_quit_add_destroy(1,GTK_OBJECT(main_window));
   /* Connect the destroy event to gtk_main_quit */
  
gtk_signal_connect(GTK_OBJECT(main_window),"destroy",G_CALLBACK(gtk_main_quit),NULL);

   /* Create OpenGL config */
   /* No double-buffer because rendering to Off-screen Pixmap */
   glconfig = gdk_gl_config_new_by_mode(GDK_GL_MODE_RGBA|GDK_GL_MODE_DEPTH);
   if( glconfig == NULL ) {
      g_print ("*** Problem with GtkGLExt.\n");
      exit(1);
   }

   /* Create a GdkPixmap */
   pixmap = gdk_pixmap_new(NULL,100,100,gdk_gl_config_get_depth(glconfig));
   /* Set GL capability of GdkPixmap */
   glpixmap = gdk_pixmap_set_gl_capability(pixmap,glconfig,NULL);
   /* Bind GdkPixmap to the GtkImage for display */
   image = gtk_image_new_from_pixmap(pixmap,NULL);
   /* Get GL drawable (rendering surface) from GL-capable GdkPixmap */
   gldrawable = gdk_pixmap_get_gl_drawable(pixmap);
   /* Create a new GL context (rendering context) from GL drawable */
   glcontext = gdk_gl_context_new(gldrawable,NULL,TRUE,GDK_GL_RGBA_TYPE);
   /* Add GtkImage to which the GdkPixmap is attached to main_window */
   gtk_container_add(GTK_CONTAINER(main_window),image);

   gtk_widget_show_all(main_window);

   /* The code below is from the gl_begin function of gtkglext */
   /* as defined in gdk/x11/gdkglpixmap-x11.c (with slight modifs) */
   glxpixmap = GDK_GL_PIXMAP_GLXPIXMAP(glpixmap);
   glxcontext = GDK_GL_CONTEXT_GLXCONTEXT(glcontext);

   Display* xdisplay = GDK_GL_CONFIG_XDISPLAY(glconfig);
   /* This crashes if DRI enabled but works if DRI disabled */
   fprintf( stderr, "[*** I got as far as glXMakeCurrent ***]\n" );
   glXMakeCurrent(xdisplay,glxpixmap,glxcontext);
   fprintf( stderr, "[*** I survived glXMakeCurrent ***]\n" );

   gtk_main();

   return(0);
}