Mercurial > sdl-ios-xcode
view src/video/SDL_rect.c @ 2909:3da0bb421d83
Added line clipping
author | Sam Lantinga <slouken@libsdl.org> |
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date | Tue, 23 Dec 2008 02:23:18 +0000 |
parents | 99210400e8b9 |
children | cdb01906cb7e |
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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 */ #include "SDL_config.h" #include "SDL_video.h" #include "SDL_rect_c.h" SDL_bool SDL_HasIntersection(const SDL_Rect * A, const SDL_Rect * B) { int Amin, Amax, Bmin, Bmax; /* Horizontal intersection */ Amin = A->x; Amax = Amin + A->w; Bmin = B->x; Bmax = Bmin + B->w; if (Bmin > Amin) Amin = Bmin; if (Bmax < Amax) Amax = Bmax; if (Amax <= Amin) return SDL_FALSE; /* Vertical intersection */ Amin = A->y; Amax = Amin + A->h; Bmin = B->y; Bmax = Bmin + B->h; if (Bmin > Amin) Amin = Bmin; if (Bmax < Amax) Amax = Bmax; if (Amax <= Amin) return SDL_FALSE; return SDL_TRUE; } SDL_bool SDL_IntersectRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result) { int Amin, Amax, Bmin, Bmax; /* Horizontal intersection */ Amin = A->x; Amax = Amin + A->w; Bmin = B->x; Bmax = Bmin + B->w; if (Bmin > Amin) Amin = Bmin; result->x = Amin; if (Bmax < Amax) Amax = Bmax; result->w = Amax - Amin; /* Vertical intersection */ Amin = A->y; Amax = Amin + A->h; Bmin = B->y; Bmax = Bmin + B->h; if (Bmin > Amin) Amin = Bmin; result->y = Amin; if (Bmax < Amax) Amax = Bmax; result->h = Amax - Amin; return !SDL_RectEmpty(result); } void SDL_UnionRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result) { int Amin, Amax, Bmin, Bmax; /* Horizontal union */ Amin = A->x; Amax = Amin + A->w; Bmin = B->x; Bmax = Bmin + B->w; if (Bmin < Amin) Amin = Bmin; result->x = Amin; if (Bmax > Amax) Amax = Bmax; result->w = Amax - Amin; /* Vertical intersection */ Amin = A->y; Amax = Amin + A->h; Bmin = B->y; Bmax = Bmin + B->h; if (Bmin < Amin) Amin = Bmin; result->y = Amin; if (Bmax > Amax) Amax = Bmax; result->h = Amax - Amin; } SDL_bool SDL_IntersectRectAndLine(const SDL_Rect *rect, int *X1, int *Y1, int *X2, int *Y2) { int x1, y1; int x2, y2; int rectx1; int recty1; int rectx2; int recty2; if (!rect || !X1 || !Y1 || !X2 || !Y2) { SDL_FALSE; } x1 = *X1; y1 = *Y1; x2 = *X2; y2 = *Y2; rectx1 = rect->x; recty1 = rect->y; rectx2 = rect->x + rect->w - 1; recty2 = rect->y + rect->h - 1; /* Check to see if entire line is inside rect */ if (x1 >= rectx1 && x1 <= rectx2 && x2 >= rectx1 && x2 <= rectx2 && y1 >= recty1 && y1 <= recty2 && y2 >= recty1 && y2 <= recty2) { return SDL_TRUE; } /* Check to see if entire line is outside rect */ if ((x1 < rectx1 && x2 < rectx1) || (x1 > rectx2 && x2 > rectx2) || (y1 < recty1 && y2 < recty2) || (y1 > recty2 && y2 > recty2)) { return SDL_FALSE; } if (y1 = y2) { /* Horizontal line, easy to clip */ if (x1 < rectx1) { *X1 = rectx1; } else if (x1 > rectx2) { *X1 = rectx2; } if (x2 < rectx1) { *X2 = rectx1; } else if (x2 > rectx2) { *X2 = rectx2; } return SDL_TRUE; } if (x1 == x2) { /* Vertical line, easy to clip */ if (y1 < recty1) { *Y1 = recty1; } else if (y1 > recty2) { *Y1 = recty2; } if (y2 < recty1) { *Y2 = recty1; } else if (y2 > recty2) { *Y2 = recty2; } return SDL_TRUE; } /* FIXME: need code to clip diagonal line to rect */ return SDL_FALSE; } void SDL_AddDirtyRect(SDL_DirtyRectList * list, const SDL_Rect * rect) { SDL_DirtyRect *dirty; /* FIXME: At what point is this optimization too expensive? */ for (dirty = list->list; dirty; dirty = dirty->next) { if (SDL_HasIntersection(&dirty->rect, rect)) { SDL_UnionRect(&dirty->rect, rect, &dirty->rect); return; } } if (list->free) { dirty = list->free; list->free = dirty->next; } else { dirty = (SDL_DirtyRect *) SDL_malloc(sizeof(*dirty)); if (!dirty) { return; } } dirty->rect = *rect; dirty->next = list->list; list->list = dirty; } void SDL_ClearDirtyRects(SDL_DirtyRectList * list) { SDL_DirtyRect *prev, *curr; /* Skip to the end of the free list */ prev = NULL; for (curr = list->free; curr; curr = curr->next) { prev = curr; } /* Add the list entries to the end */ if (prev) { prev->next = list->list; } else { list->free = list->list; } list->list = NULL; } void SDL_FreeDirtyRects(SDL_DirtyRectList * list) { while (list->list) { SDL_DirtyRect *elem = list->list; list->list = elem->next; SDL_free(elem); } while (list->free) { SDL_DirtyRect *elem = list->free; list->free = elem->next; SDL_free(elem); } } /* vi: set ts=4 sw=4 expandtab: */