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view docs/man3/SDL_SemTryWait.3 @ 2359:b70b96e615d2 gsoc2008_iphone

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These files are the OpenGL ES render driver. You should be able to use them on any platform that supports OpenGL ES -- not just iPhone. The driver is based off the OpenGL render driver. There are a few differences between OpenGL and OpenGL ES that present difficulties for this driver: - OpenGL ES does NOT support many pixel formats (for example, no GL_BGR). Also, when using texture functions format and internalFormat must be the same -- this means 32 bit packed formats like SDL_PIXELFORMAT_BGR888 cannot be automatically converted to GL_RGB (which is 24bpp). - OpenGL ES doesn't have GL_PACK_ROW_LENGTH, which means data must be reformatted before uploading changes to dirty rects. This change has been added. - OpenGL ES doesn't support paletted textures, though there is an extension. I'm looking into this. Some other notable differences: - OpenGL ES has an extension called GL_OES_draw_texture which allows for quicker 2D sprite-type drawing. I use this in GL_RenderCopy when it is available. The iPhone supports the extension, but the iPhone Simulator does not (presently). - No glBegin() / glEnd() and no GL_QUADS! I'm using glDrawArrays with GL_TRIANGLE_STRIP instead!
author Holmes Futrell <hfutrell@umail.ucsb.edu>
date Thu, 17 Jul 2008 23:31:42 +0000
parents 546f7c1eb755
children 1238da4a7112
line wrap: on
line source

.TH "SDL_SemTryWait" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_SemTryWait \- Attempt to lock a semaphore but don\&'t suspend the thread\&.
.SH "SYNOPSIS"
.PP
\fB#include "SDL\&.h"
#include "SDL_thread\&.h"
.sp
\fBint \fBSDL_SemTryWait\fP\fR(\fBSDL_sem *sem\fR);
.SH "DESCRIPTION"
.PP
\fBSDL_SemTryWait\fP is a non-blocking varient of \fI\fBSDL_SemWait\fP\fR\&. If the value of the semaphore pointed to by \fBsem\fR is positive it will atomically decrement the semaphore value and return 0, otherwise it will return \fBSDL_MUTEX_TIMEOUT\fR instead of suspending the thread\&.
.PP
After \fBSDL_SemTryWait\fP is successful, the semaphore can be released and its count atomically incremented by a successful call to \fISDL_SemPost\fR\&.
.SH "RETURN VALUE"
.PP
Returns \fB0\fR if the semaphore was successfully locked or either \fBSDL_MUTEX_TIMEOUT\fR or \fB-1\fR if the thread would have suspended or there was an error, respectivly\&.
.PP
If the semaphore was not successfully locked, the semaphore will be unchanged\&.
.SH "EXAMPLES"
.PP
.PP
.nf
\f(CWres = SDL_SemTryWait(my_sem);

if (res == SDL_MUTEX_TIMEOUT) {
        return TRY_AGAIN;
}
if (res == -1) {
        return WAIT_ERROR;
}

\&.\&.\&.

SDL_SemPost(my_sem);\fR
.fi
.PP
.SH "SEE ALSO"
.PP
\fI\fBSDL_CreateSemaphore\fP\fR, \fI\fBSDL_DestroySemaphore\fP\fR, \fI\fBSDL_SemWait\fP\fR, \fI\fBSDL_SemWaitTimeout\fP\fR, \fI\fBSDL_SemPost\fP\fR, \fI\fBSDL_SemValue\fP\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00