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view test/automated/common/common.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 | 22ac66da0765 |
children | 9f62f47d989b |
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/** * Automated SDL test common framework. * * Written by Edgar Simo "bobbens" * * Released under Public Domain. */ #ifndef COMMON_H # define COMMON_H #if (SDL_BYTEORDER == SDL_BIG_ENDIAN) # define RMASK 0xff000000 /**< Red bit mask. */ # define GMASK 0x00ff0000 /**< Green bit mask. */ # define BMASK 0x0000ff00 /**< Blue bit mask. */ # define AMASK 0x000000ff /**< Alpha bit mask. */ #else # define RMASK 0x000000ff /**< Red bit mask. */ # define GMASK 0x0000ff00 /**< Green bit mask. */ # define BMASK 0x00ff0000 /**< Blue bit mask. */ # define AMASK 0xff000000 /**< Alpha bit mask. */ #endif typedef struct SurfaceImage_s { int width; int height; unsigned int bytes_per_pixel; /* 3:RGB, 4:RGBA */ const unsigned char pixel_data[]; } SurfaceImage_t; /** * @brief Compares a surface and a surface image for equality. * * @param sur Surface to compare. * @param img Image to compare against. * @return 0 if they are the same, -1 on error and positive if different. */ int surface_compare( SDL_Surface *sur, const SurfaceImage_t *img ); #endif /* COMMON_H */