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annotate INSTALL @ 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> |
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date | Sat, 03 Oct 2009 16:23:16 +0000 |
parents | 0a45995a7fc3 |
children | 00e7c6b7eb03 |
rev | line source |
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0 | 1 |
2 To compile and install SDL: | |
3 | |
4 1. Run './configure; make; make install' | |
5 | |
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0a45995a7fc3
Date: Tue, 2 Mar 2004 11:34:54 +0100
Sam Lantinga <slouken@libsdl.org>
parents:
533
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6 If you are compiling for Windows using gcc, read the FAQ at: |
0a45995a7fc3
Date: Tue, 2 Mar 2004 11:34:54 +0100
Sam Lantinga <slouken@libsdl.org>
parents:
533
diff
changeset
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7 http://www.libsdl.org/faq.php?action=listentries&category=4#42 |
0 | 8 |
9 If you are compiling using Visual C++ on Win32, you should read | |
10 the file VisualC.html | |
11 | |
12 2. Look at the example programs in ./test, and check out the HTML | |
13 documentation in ./docs to see how to use the SDL library. | |
14 | |
15 3. Join the SDL developer mailing list by sending E-mail to | |
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Updated mailing list information
Sam Lantinga <slouken@libsdl.org>
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16 sdl-request@libsdl.org |
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Updated mailing list information
Sam Lantinga <slouken@libsdl.org>
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17 and put "subscribe" in the subject of the message. |
0 | 18 |
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Updated mailing list information
Sam Lantinga <slouken@libsdl.org>
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19 Or alternatively you can use the web interface: |
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Sam Lantinga <slouken@libsdl.org>
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20 http://www.libsdl.org/mailing-list.php |
0 | 21 |
22 That's it! | |
23 Sam Lantinga <slouken@libsdl.org> |