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view docs/man3/SDL_CD.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_CD" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" .SH "NAME" SDL_CD \- CDROM Drive Information .SH "STRUCTURE DEFINITION" .PP .nf \f(CWtypedef struct{ int id; CDstatus status; int numtracks; int cur_track; int cur_frame; SDL_CDtrack track[SDL_MAX_TRACKS+1]; } SDL_CD;\fR .fi .PP .SH "STRUCTURE DATA" .TP 20 \fBid\fR Private drive identifier .TP 20 \fBstatus\fR Drive \fIstatus\fR .TP 20 \fBnumtracks\fR Number of tracks on the CD .TP 20 \fBcur_track\fR Current track .TP 20 \fBcur_frame\fR Current frame offset within the track .TP 20 \fBtrack\fR[SDL_MAX_TRACKS+1] Array of track descriptions\&. (see \fI\fBSDL_CDtrack\fR\fR) .SH "DESCRIPTION" .PP An \fBSDL_CD\fR structure is returned by \fI\fBSDL_CDOpen\fP\fR\&. It represents an opened CDROM device and stores information on the layout of the tracks on the disc\&. .PP A frame is the base data unit of a CD\&. \fBCD_FPS\fP frames is equal to 1 second of music\&. SDL provides two macros for converting between time and frames: \fBFRAMES_TO_MSF(f, M,S,F)\fP and \fBMSF_TO_FRAMES\fP\&. .SH "EXAMPLES" .PP .nf \f(CWint min, sec, frame; int frame_offset; FRAMES_TO_MSF(cdrom->cur_frame, &min, &sec, &frame); printf("Current Position: %d minutes, %d seconds, %d frames ", min, sec, frame); frame_offset=MSF_TO_FRAMES(min, sec, frame);\fR .fi .PP .SH "SEE ALSO" .PP \fI\fBSDL_CDOpen\fP\fR, \fI\fBSDL_CDtrack\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58