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view docs/man3/SDL_CreateMutex.3 @ 3333:b334b4f7dfa0
[SDL] Bad math in SDL_RenderCopy
Mason Wheeler to sdl
When I tried to render an image using something other than NULL for srcrect, it got horribly distorted. I traced it down to the fact that the math in the rectangle adjustments performed just before the call to renderer->RenderCopy is written inside out. It should look like this:
if (dstrect->w != real_dstrect.w) {
int deltax = (dstrect->x - real_dstrect.x);
int deltaw = (dstrect->w - real_dstrect.w);
real_srcrect.x += (deltax * real_srcrect.w) / dstrect->w;
real_srcrect.w += (deltaw * real_srcrect.w) / dstrect->w;
}
if (dstrect->h != real_dstrect.h) {
int deltay = (dstrect->y - real_dstrect.y);
int deltah = (dstrect->h - real_dstrect.h);
real_srcrect.y += (deltay * real_srcrect.h) / dstrect->h;
real_srcrect.h += (deltah * real_srcrect.h) / dstrect->h;
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Sat, 03 Oct 2009 16:23:16 +0000 |
parents | 546f7c1eb755 |
children | 1238da4a7112 |
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.TH "SDL_CreateMutex" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" .SH "NAME" SDL_CreateMutex \- Create a mutex .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" #include "SDL_thread\&.h" .sp \fBSDL_mutex *\fBSDL_CreateMutex\fP\fR(\fBvoid\fR); .SH "DESCRIPTION" .PP Create a new, unlocked mutex\&. .SH "EXAMPLES" .PP .nf \f(CWSDL_mutex *mut; mut=SDL_CreateMutex(); \&. \&. if(SDL_mutexP(mut)==-1){ fprintf(stderr, "Couldn\&'t lock mutex "); exit(-1); } \&. /* Do stuff while mutex is locked */ \&. \&. if(SDL_mutexV(mut)==-1){ fprintf(stderr, "Couldn\&'t unlock mutex "); exit(-1); } SDL_DestroyMutex(mut); \fR .fi .PP .SH "SEE ALSO" .PP \fI\fBSDL_mutexP\fP\fR, \fI\fBSDL_mutexV\fP\fR, \fI\fBSDL_DestroyMutex\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00