Mercurial > sdl-ios-xcode
changeset 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 | da1cb54d74ef |
| children | 61ea9005fddf |
| files | src/video/SDL_video.c |
| diffstat | 1 files changed, 4 insertions(+), 4 deletions(-) [+] |
line wrap: on
line diff
--- a/src/video/SDL_video.c Fri Oct 02 13:50:36 2009 +0000 +++ b/src/video/SDL_video.c Sat Oct 03 16:23:16 2009 +0000 @@ -2463,14 +2463,14 @@ if (dstrect->w != real_dstrect.w) { int deltax = (real_dstrect.x - dstrect->x); int deltaw = (real_dstrect.w - dstrect->w); - real_srcrect.x += (deltax * dstrect->w) / real_srcrect.w; - real_srcrect.w += (deltaw * dstrect->w) / real_srcrect.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 = (real_dstrect.y - dstrect->y); int deltah = (real_dstrect.h - dstrect->h); - real_srcrect.y += (deltay * dstrect->h) / real_srcrect.h; - real_srcrect.h += (deltah * dstrect->h) / real_srcrect.h; + real_srcrect.y += (deltay * real_srcrect.h) / dstrect->h; + real_srcrect.h += (deltah * real_srcrect.h) / dstrect->h; } }