From 03a11cad73d46a5e533c7a2b41afa6b8d9f0117d Mon Sep 17 00:00:00 2001 From: Sam Lantinga Date: Sat, 3 Oct 2009 16:23:16 +0000 Subject: [PATCH] [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; --- src/video/SDL_video.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/src/video/SDL_video.c b/src/video/SDL_video.c index 1f6be3891..8c42fe326 100644 --- a/src/video/SDL_video.c +++ b/src/video/SDL_video.c @@ -2463,14 +2463,14 @@ SDL_RenderCopy(SDL_TextureID textureID, const SDL_Rect * srcrect, 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; } }