Fixed bug 3029 - software renderer cuts off edges when rotate-blitting with a multiple of 90 degrees

Adam M.

When doing a rotated texture copy with the software renderer, where the angle is a multiple of 90 degrees, one or two edges of the image get cut off. This is because of the following line in sw_rotate.c:
    if ((unsigned)dx < (unsigned)sw && (unsigned)dy < (unsigned)sh) {
which is effectively saying:
    if (dx >= 0 && dx < src->w-1 && dy >= 0 && dy < src->h-1) {

As a result, it doesn't process pixels in the right column or bottom row of the source image (except when they're accessed as part of the bilinear filtering for nearby pixels). This causes it to look like the edges are cut off, and it's especially obvious with an exact multiple of 90 degrees.
This commit is contained in:
Sam Lantinga 2016-10-07 18:00:30 -07:00
parent 5c2320f113
commit 9c48365524
3 changed files with 123 additions and 34 deletions

View file

@ -677,8 +677,8 @@ SW_RenderCopyEx(SDL_Renderer * renderer, SDL_Texture * texture,
}
if (!retval) {
SDLgfx_rotozoomSurfaceSizeTrig(tmp_rect.w, tmp_rect.h, -angle, &dstwidth, &dstheight, &cangle, &sangle);
surface_rotated = SDLgfx_rotateSurface(surface_scaled, -angle, dstwidth/2, dstheight/2, GetScaleQuality(), flip & SDL_FLIP_HORIZONTAL, flip & SDL_FLIP_VERTICAL, dstwidth, dstheight, cangle, sangle);
SDLgfx_rotozoomSurfaceSizeTrig(tmp_rect.w, tmp_rect.h, angle, &dstwidth, &dstheight, &cangle, &sangle);
surface_rotated = SDLgfx_rotateSurface(surface_scaled, angle, dstwidth/2, dstheight/2, GetScaleQuality(), flip & SDL_FLIP_HORIZONTAL, flip & SDL_FLIP_VERTICAL, dstwidth, dstheight, cangle, sangle);
if(surface_rotated) {
/* Find out where the new origin is by rotating the four final_rect points around the center and then taking the extremes */
abscenterx = final_rect.x + (int)center->x;