Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_VideoModeOK.3 @ 1544:ab1e4c41ab71
Fixed bug #33
Mike Frysinger wrote:
> with libsdl-1.2.9, some games (like bomberclone) started
> segfaulting in Gentoo
[...snip...]
> the last change in the last hunk:
[...snip...]
> if i change the statement to read:
> (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures()
> bomberclone no longer segfaults on my box
Alex Volkov wrote:
> The test "(table[which].blit_features & GetBlitFeatures()) ==
> table[which].blit_features)" is correct, and the previous
> "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken.
I think there is potentially a slightly different cause of the above problem.
During the introduction of the Altivec code, the blit_table struct field
'alpha' got changed from a straightforward enum to a bitmask, which makes
perfect sense by itself. However, now the table driven blitter selection code
in SDL_CalculateBlitN() can choose the wrong blitters when searching for a
NO_ALPHA blitter because of the following code:
int a_need = 0;
...
(a_need & table[which].alpha) == a_need &&
When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like
Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing
alpha channel bits to appear in a non-alpha destination surface. I suppose this
could theoretically be an indirect cause of the segfault mentioned above.
I *think* this can be fixed by changing to
int a_need = NO_ALPHA;
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Wed, 15 Mar 2006 15:47:49 +0000 |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
rev | line source |
---|---|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
1 .TH "SDL_VideoModeOK" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
0 | 2 .SH "NAME" |
3 SDL_VideoModeOK\- Check to see if a particular video mode is supported\&. | |
4 .SH "SYNOPSIS" | |
5 .PP | |
6 \fB#include "SDL\&.h" | |
7 .sp | |
8 \fBint \fBSDL_VideoModeOK\fP\fR(\fBint width, int height, int bpp, Uint32 flags\fR); | |
9 .SH "DESCRIPTION" | |
10 .PP | |
11 \fBSDL_VideoModeOK\fP returns \fB0\fR if the requested mode is not supported under any bit depth, or returns the bits-per-pixel of the closest available mode with the given width, height and requested \fIsurface\fR flags (see \fI\fBSDL_SetVideoMode\fP\fR)\&. | |
12 .PP | |
13 The bits-per-pixel value returned is only a suggested mode\&. You can usually request and bpp you want when \fIsetting\fR the video mode and SDL will emulate that color depth with a shadow video surface\&. | |
14 .PP | |
15 The arguments to \fBSDL_VideoModeOK\fP are the same ones you would pass to \fISDL_SetVideoMode\fR | |
16 .SH "EXAMPLE" | |
17 .PP | |
18 .nf | |
19 \f(CWSDL_Surface *screen; | |
20 Uint32 bpp; | |
21 \&. | |
22 \&. | |
23 \&. | |
24 printf("Checking mode 640x480@16bpp\&. | |
25 "); | |
26 bpp=SDL_VideoModeOK(640, 480, 16, SDL_HWSURFACE); | |
27 | |
28 if(!bpp){ | |
29 printf("Mode not available\&. | |
30 "); | |
31 exit(-1); | |
32 } | |
33 | |
34 printf("SDL Recommends 640x480@%dbpp\&. | |
35 ", bpp); | |
36 screen=SDL_SetVideoMode(640, 480, bpp, SDL_HWSURFACE); | |
37 \&. | |
38 \&.\fR | |
39 .fi | |
40 .PP | |
41 .SH "SEE ALSO" | |
42 .PP | |
43 \fI\fBSDL_SetVideoMode\fP\fR, \fI\fBSDL_GetVideoInfo\fP\fR | |
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
44 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |