Mercurial > sdl-ios-xcode
view include/SDL_error.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 | 99210400e8b9 |
children | d3baf5ac4e37 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2009 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ /** * \file SDL_error.h * Simple error message routines for SDL */ #ifndef _SDL_error_h #define _SDL_error_h #include "SDL_stdinc.h" #include "begin_code.h" /* Set up for C function definitions, even when using C++ */ #ifdef __cplusplus /* *INDENT-OFF* */ extern "C" { /* *INDENT-ON* */ #endif /* Public functions */ extern DECLSPEC void SDLCALL SDL_SetError(const char *fmt, ...); extern DECLSPEC char *SDLCALL SDL_GetError(void); extern DECLSPEC void SDLCALL SDL_ClearError(void); /* Private error message function - used internally */ #define SDL_OutOfMemory() SDL_Error(SDL_ENOMEM) #define SDL_Unsupported() SDL_Error(SDL_UNSUPPORTED) typedef enum { SDL_ENOMEM, SDL_EFREAD, SDL_EFWRITE, SDL_EFSEEK, SDL_UNSUPPORTED, SDL_LASTERROR } SDL_errorcode; extern DECLSPEC void SDLCALL SDL_Error(SDL_errorcode code); /* Ends C function definitions when using C++ */ #ifdef __cplusplus /* *INDENT-OFF* */ } /* *INDENT-ON* */ #endif #include "close_code.h" #endif /* _SDL_error_h */ /* vi: set ts=4 sw=4 expandtab: */