GLXPixmap and radeon driver

[Glynn Clements]

I have the following code, which tries to set up OpenGL rendering to a
GLXPixmap:

	static Display *dpy;
	static int scr;
	static GLXContext ctx;

	#ifdef HAVE_PIXMAPS
	Pixmap pixmap;
	static GLXPixmap glxpixmap;
	#endif

	...

	static void create_pixmap(int width, int height)
	{
	#ifdef HAVE_PIXMAPS
	    static int att[] = {
		GLX_RGBA,
		GLX_RED_SIZE, 1,
		GLX_GREEN_SIZE, 1,
		GLX_BLUE_SIZE, 1,
		GLX_DEPTH_SIZE, 1,
		None
	    };
	    XVisualInfo *vi;
	
	    if (getenv("GRASS_NO_GLX_PIXMAPS"))
		return;
	
	    fprintf(stderr, "Create PixMap Using GLX 1.1\n");
	
	    vi = glXChooseVisual(dpy, scr, att);
	    if (!vi) {
		fprintf(stderr, "Unable to get Visual\n");
		return;
	    }
	
	    ctx = glXCreateContext(dpy, vi, NULL, GL_FALSE);
	    if (!ctx) {
		fprintf(stderr, "Unable to create context\n");
		return;
	    }
	
	    pixmap = XCreatePixmap(dpy, RootWindow(dpy, vi->screen),
				   width, height, vi->depth);
	    if (!pixmap) {
		fprintf(stderr, "Unable to create pixmap\n");
		return;
	    }
	    glxpixmap = glXCreateGLXPixmap(dpy, vi, pixmap);
	    if (!glxpixmap) {
		fprintf(stderr, "Unable to create GLX pixmap\n");
		return;
	    }
	    if (!glXMakeCurrent(dpy, glxpixmap, ctx)) {
		fprintf(stderr, "Unable to use context\n");
		glXDestroyGLXPixmap(dpy, glxpixmap);
		glxpixmap = None;
		return;
	    }
	#endif
	}

It isn't essential that the code succeeds. If glxpixmap is None, a
fall-back will be used.

The code works fine with the nv and nvidia drivers, and with Cygwin's
XWin.exe.

However, I'm getting a report that with the following setup:

	 Debian testing x86, X.Org 7.2, Mesa 7.0.3 rc2, "radeon" driver 6.6.3, Ati
	 Radeon Mobility X700, GRASS SVN r30759.

the glXMakeCurrent() call generates a GLXBadContext error then
terminates the program.

So:

1. Is the code doing something wrong?

2. Is there anything which it can do to determine that it can't use a
GLXPixmap (without terminating the program)?

3. Is this a known issue which has since been fixed in a later version
of the driver (or some other part of X)?

FWIW:

Bug report:

	http://trac.osgeo.org/grass/ticket/104#comment:6

Source code:

	http://trac.osgeo.org/grass/browser/grass/trunk/visualization/nviz/src/do_zoom.c

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