Mercurial > sdl-ios-xcode
view test/testsem.c @ 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 | c121d94672cb |
children | d547877e355e |
line wrap: on
line source
/* Simple test of the SDL semaphore code */ #include <stdio.h> #include <stdlib.h> #include <signal.h> #include "SDL.h" #include "SDL_thread.h" #define NUM_THREADS 10 static SDL_sem *sem; int alive = 1; int SDLCALL ThreadFunc(void *data) { int threadnum = (int) (uintptr_t) data; while (alive) { SDL_SemWait(sem); fprintf(stderr, "Thread number %d has got the semaphore (value = %d)!\n", threadnum, SDL_SemValue(sem)); SDL_Delay(200); SDL_SemPost(sem); fprintf(stderr, "Thread number %d has released the semaphore (value = %d)!\n", threadnum, SDL_SemValue(sem)); SDL_Delay(1); /* For the scheduler */ } printf("Thread number %d exiting.\n", threadnum); return 0; } static void killed(int sig) { alive = 0; } int main(int argc, char **argv) { SDL_Thread *threads[NUM_THREADS]; uintptr_t i; int init_sem; if (argc < 2) { fprintf(stderr, "Usage: %s init_value\n", argv[0]); return (1); } /* Load the SDL library */ if (SDL_Init(0) < 0) { fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError()); return (1); } signal(SIGTERM, killed); signal(SIGINT, killed); init_sem = atoi(argv[1]); sem = SDL_CreateSemaphore(init_sem); printf("Running %d threads, semaphore value = %d\n", NUM_THREADS, init_sem); /* Create all the threads */ for (i = 0; i < NUM_THREADS; ++i) { threads[i] = SDL_CreateThread(ThreadFunc, (void *) i); } /* Wait 10 seconds */ SDL_Delay(10 * 1000); /* Wait for all threads to finish */ printf("Waiting for threads to finish\n"); alive = 0; for (i = 0; i < NUM_THREADS; ++i) { SDL_WaitThread(threads[i], NULL); } printf("Finished waiting for threads\n"); SDL_DestroySemaphore(sem); SDL_Quit(); return (0); }