SDL_SetVideoMode() failing and not setting an error (patch)

Running an OpenGL SDL application off 1.2.7, at SDL_InitSubSystem(SDL_INIT_VIDEO) time:

Warning: Unable to initialize AAlib mouseUsing AAlib driver: Slang driver 1.0 (slang)

SDL_SetVideoMode then fails; SDL_GetError() returns “”.

The installation problem is straightforward: X (the higher priority
driver) isn’t running, so SDL is falling back on aalib. However,
no error is being set when aalib fails to initialize. This also
happens with the svgalib driver.

SDL_video.c line ~653 sets mode to NULL, since aalib didn’t return an
OpenGL surface. Line ~711 (“failed setting a video mode”) returns NULL.
The attached patch sets an error. It’s a horrible, useless error
message–it should really say eg. “aalib does not support OpenGL”; this
should probably be done earlier in the individual drivers, too.

As a workaround (to make sure error messages are sane, and to make sure
flaky libraries like svgalib are never accidentally used), I’ll probably
force SDL_VIDEODRIVER to “x11” in Linux if it’s not set; it’s the only
way to get reasonably accelerated OpenGL, anyway.–
Glenn Maynard
-------------- next part --------------
— SDL_video.c 2004-02-18 12:22:04.000000000 -0500
+++ /home/glenn/SDL_video.c.diff 2004-04-10 02:23:06.000000000 -0400
@@ -651,6 +651,7 @@
/* Sam - If we asked for OpenGL mode, and didn’t get it, fail */
if ( is_opengl && !(mode->flags & SDL_OPENGL) ) {
mode = NULL;

  •   SDL_SetError("OpenGL not available");

Thanks, patch applied.

See ya!
-Sam Lantinga, Software Engineer, Blizzard Entertainment