view docs/man3/SDL_JoystickGetAxis.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
line wrap: on
line source

.TH "SDL_JoystickGetAxis" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_JoystickGetAxis\- Get the current state of an axis
.SH "SYNOPSIS"
.PP
\fB#include "SDL\&.h"
.sp
\fBSint16 \fBSDL_JoystickGetAxis\fP\fR(\fBSDL_Joystick *joystick, int axis\fR);
.SH "DESCRIPTION"
.PP
\fBSDL_JoystickGetAxis\fP returns the current state of the given \fBaxis\fR on the given \fBjoystick\fR\&.
.PP
On most modern joysticks the X axis is usually represented by \fBaxis\fR 0 and the Y axis by \fBaxis\fR 1\&. The value returned by \fBSDL_JoystickGetAxis\fP is a signed integer (-32768 to 32768) representing the current position of the \fBaxis\fR, it maybe necessary to impose certain tolerances on these values to account for jitter\&. It is worth noting that some joysticks use axes 2 and 3 for extra buttons\&.
.SH "RETURN VALUE"
.PP
Returns a 16-bit signed integer representing the current position of the \fBaxis\fR\&.
.SH "EXAMPLES"
.PP
.PP
.nf
\f(CWSint16 x_move, y_move;
SDL_Joystick *joy1;
\&.
\&.
x_move=SDL_JoystickGetAxis(joy1, 0);
y_move=SDL_JoystickGetAxis(joy1, 1);\fR
.fi
.PP
.SH "SEE ALSO"
.PP
\fI\fBSDL_JoystickNumAxes\fP\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00