Mercurial > sdl-ios-xcode
annotate src/video/win32/SDL_ceddrawrender.h @ 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 | 6338b7f2d024 |
children | f7b03b6838cb |
rev | line source |
---|---|
3168 | 1 /* |
2 SDL - Simple DirectMedia Layer | |
3 Copyright (C) 1997-2009 Sam Lantinga | |
4 | |
5 This library is free software; you can redistribute it and/or | |
6 modify it under the terms of the GNU Lesser General Public | |
7 License as published by the Free Software Foundation; either | |
8 version 2.1 of the License, or (at your option) any later version. | |
9 | |
10 This library is distributed in the hope that it will be useful, | |
11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 Lesser General Public License for more details. | |
14 | |
15 You should have received a copy of the GNU Lesser General Public | |
16 License along with this library; if not, write to the Free Software | |
17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
18 | |
19 Sam Lantinga | |
20 slouken@libsdl.org | |
21 | |
22 Stefan Klug | |
23 klug.stefan@gmx.de | |
24 */ | |
25 #include "SDL_config.h" | |
26 | |
27 #if SDL_VIDEO_RENDER_DDRAW | |
28 extern void DDRAW_AddRenderDriver(_THIS); | |
29 #endif | |
30 | |
31 /* vi: set ts=4 sw=4 expandtab: */ |