Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_Flip.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> |
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date | Wed, 15 Mar 2006 15:47:49 +0000 |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
rev | line source |
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181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
1 .TH "SDL_Flip" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
0 | 2 .SH "NAME" |
3 SDL_Flip\- Swaps screen buffers | |
4 .SH "SYNOPSIS" | |
5 .PP | |
6 \fB#include "SDL\&.h" | |
7 .sp | |
8 \fBint \fBSDL_Flip\fP\fR(\fBSDL_Surface *screen\fR); | |
9 .SH "DESCRIPTION" | |
10 .PP | |
11 On hardware that supports double-buffering, this function sets up a flip and returns\&. The hardware will wait for vertical retrace, and then swap video buffers before the next video surface blit or lock will return\&. On hardware that doesn\&'t support double-buffering, this is equivalent to calling \fISDL_UpdateRect\fR\fB(screen, 0, 0, 0, 0)\fR | |
12 .PP | |
13 The \fBSDL_DOUBLEBUF\fP flag must have been passed to \fISDL_SetVideoMode\fR, when setting the video mode for this function to perform hardware flipping\&. | |
14 .SH "RETURN VALUE" | |
15 .PP | |
16 This function returns \fB0\fR if successful, or \fB-1\fR if there was an error\&. | |
17 .SH "SEE ALSO" | |
18 .PP | |
19 \fI\fBSDL_SetVideoMode\fP\fR, \fI\fBSDL_UpdateRect\fP\fR, \fI\fBSDL_Surface\fR\fR | |
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
20 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |