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view docs/man3/SDL_CDOpen.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_CDOpen" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" .SH "NAME" SDL_CDOpen \- Opens a CD-ROM drive for access\&. .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBSDL_CD *\fBSDL_CDOpen\fP\fR(\fBint drive\fR); .SH "DESCRIPTION" .PP Opens a CD-ROM drive for access\&. It returns a \fI\fBSDL_CD\fR\fR structure on success, or \fBNULL\fP if the drive was invalid or busy\&. This newly opened CD-ROM becomes the default CD used when other CD functions are passed a \fBNULL\fP CD-ROM handle\&. .PP Drives are numbered starting with 0\&. Drive 0 is the system default CD-ROM\&. .SH "EXAMPLES" .PP .nf \f(CWSDL_CD *cdrom; int cur_track; int min, sec, frame; SDL_Init(SDL_INIT_CDROM); atexit(SDL_Quit); /* Check for CD drives */ if(!SDL_CDNumDrives()){ /* None found */ fprintf(stderr, "No CDROM devices available "); exit(-1); } /* Open the default drive */ cdrom=SDL_CDOpen(0); /* Did if open? Check if cdrom is NULL */ if(!cdrom){ fprintf(stderr, "Couldn\&'t open drive: %s ", SDL_GetError()); exit(-1); } /* Print Volume info */ printf("Name: %s ", SDL_CDName(0)); printf("Tracks: %d ", cdrom->numtracks); for(cur_track=0;cur_track < cdrom->numtracks; cur_track++){ FRAMES_TO_MSF(cdrom->track[cur_track]\&.length, &min, &sec, &frame); printf(" Track %d: Length %d:%d ", cur_track, min, sec); } SDL_CDClose(cdrom);\fR .fi .PP .SH "SEE ALSO" .PP \fI\fBSDL_CD\fR\fR, \fI\fBSDL_CDtrack\fR\fR, \fI\fBSDL_CDClose\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58