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view docs/man3/SDL_BuildAudioCVT.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_BuildAudioCVT" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" .SH "NAME" SDL_BuildAudioCVT \- Initializes a SDL_AudioCVT structure for conversion .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBint \fBSDL_BuildAudioCVT\fP\fR(\fBSDL_AudioCVT *cvt, Uint16 src_format, Uint8 src_channels, int src_rate, Uint16 dst_format, Uint8 dst_channels, int dst_rate\fR); .SH "DESCRIPTION" .PP Before an \fI\fBSDL_AudioCVT\fR\fR structure can be used to convert audio data it must be initialized with source and destination information\&. .PP \fBsrc_format\fR and \fBdst_format\fR are the source and destination format of the conversion\&. (For information on audio formats see \fI\fB SDL_AudioSpec\fR\fR)\&. \fBsrc_channels\fR and \fBdst_channels\fR are the number of channels in the source and destination formats\&. Finally, \fBsrc_rate\fR and \fBdst_rate\fR are the frequency or samples-per-second of the source and destination formats\&. Once again, see \fI\fBSDL_AudioSpec\fR\fR\&. .SH "RETURN VALUES" .PP Returns \fB-1\fR if the filter could not be built or 1 if it could\&. .SH "EXAMPLES" .PP See \fI\fBSDL_ConvertAudio\fP\fR\&. .SH "SEE ALSO" .PP \fI\fBSDL_ConvertAudio\fP\fR, \fI\fBSDL_AudioCVT\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58