| /* |
| SDL - Simple DirectMedia Layer |
| Copyright (C) 1997-2010 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_EnclosePoints(const SDL_Point * points, int count, const SDL_Rect * clip, |
| SDL_Rect * result) |
| { |
| int minx = 0; |
| int miny = 0; |
| int maxx = 0; |
| int maxy = 0; |
| int x, y, i; |
| |
| if (count < 1) { |
| return SDL_FALSE; |
| } |
| |
| if (clip) { |
| SDL_bool added = SDL_FALSE; |
| int clip_minx = clip->x; |
| int clip_miny = clip->y; |
| int clip_maxx = clip->x+clip->w-1; |
| int clip_maxy = clip->y+clip->h-1; |
| |
| for (i = 0; i < count; ++i) { |
| x = points[i].x; |
| y = points[i].y; |
| |
| if (x < clip_minx || x > clip_maxx || |
| y < clip_miny || y > clip_maxy) { |
| continue; |
| } |
| if (!added) { |
| minx = maxx = x; |
| miny = maxy = y; |
| added = SDL_TRUE; |
| continue; |
| } |
| if (x < minx) { |
| minx = x; |
| } else if (x > maxx) { |
| maxx = x; |
| } |
| if (y < miny) { |
| miny = y; |
| } else if (y > maxy) { |
| maxy = y; |
| } |
| } |
| if (!added) { |
| return SDL_FALSE; |
| } |
| } else { |
| /* No clipping, always add the first point */ |
| minx = maxx = points[0].x; |
| miny = maxy = points[0].y; |
| |
| for (i = 1; i < count; ++i) { |
| x = points[i].x; |
| y = points[i].y; |
| |
| if (x < minx) { |
| minx = x; |
| } else if (x > maxx) { |
| maxx = x; |
| } |
| if (y < miny) { |
| miny = y; |
| } else if (y > maxy) { |
| maxy = y; |
| } |
| } |
| } |
| |
| if (result) { |
| result->x = minx; |
| result->y = miny; |
| result->w = (maxx-minx)+1; |
| result->h = (maxy-miny)+1; |
| } |
| return SDL_TRUE; |
| } |
| |
| /* Use the Cohen-Sutherland algorithm for line clipping */ |
| #define CODE_BOTTOM 1 |
| #define CODE_TOP 2 |
| #define CODE_LEFT 4 |
| #define CODE_RIGHT 8 |
| |
| static int ComputeOutCode(const SDL_Rect * rect, int x, int y) |
| { |
| int code = 0; |
| if (y < 0) { |
| code |= CODE_TOP; |
| } else if (y >= rect->y + rect->h) { |
| code |= CODE_BOTTOM; |
| } |
| if (x < 0) { |
| code |= CODE_LEFT; |
| } else if (x >= rect->x + rect->w) { |
| code |= CODE_RIGHT; |
| } |
| return code; |
| } |
| |
| SDL_bool |
| SDL_IntersectRectAndLine(const SDL_Rect * rect, int *X1, int *Y1, int *X2, |
| int *Y2) |
| { |
| int x = 0; |
| int y = 0; |
| int x1, y1; |
| int x2, y2; |
| int rectx1; |
| int recty1; |
| int rectx2; |
| int recty2; |
| int outcode1, outcode2; |
| |
| if (!rect || !X1 || !Y1 || !X2 || !Y2) { |
| return 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 to one side of rect */ |
| if ((x1 < rectx1 && x2 < rectx1) || (x1 > rectx2 && x2 > rectx2) || |
| (y1 < recty1 && y2 < recty1) || (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; |
| } |
| |
| /* More complicated Cohen-Sutherland algorithm */ |
| outcode1 = ComputeOutCode(rect, x1, y1); |
| outcode2 = ComputeOutCode(rect, x2, y2); |
| while (outcode1 || outcode2) { |
| if (outcode1 & outcode2) { |
| return SDL_FALSE; |
| } |
| |
| if (outcode1) { |
| if (outcode1 & CODE_TOP) { |
| y = recty1; |
| x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1); |
| } else if (outcode1 & CODE_BOTTOM) { |
| y = recty2; |
| x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1); |
| } else if (outcode1 & CODE_LEFT) { |
| x = rectx1; |
| y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1); |
| } else if (outcode1 & CODE_RIGHT) { |
| x = rectx2; |
| y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1); |
| } |
| x1 = x; |
| y1 = y; |
| outcode1 = ComputeOutCode(rect, x, y); |
| } else { |
| if (outcode2 & CODE_TOP) { |
| y = recty1; |
| x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1); |
| } else if (outcode2 & CODE_BOTTOM) { |
| y = recty2; |
| x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1); |
| } else if (outcode2 & CODE_LEFT) { |
| x = rectx1; |
| y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1); |
| } else if (outcode2 & CODE_RIGHT) { |
| x = rectx2; |
| y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1); |
| } |
| x2 = x; |
| y2 = y; |
| outcode2 = ComputeOutCode(rect, x, y); |
| } |
| } |
| *X1 = x1; |
| *Y1 = y1; |
| *X2 = x2; |
| *Y2 = y2; |
| return SDL_TRUE; |
| } |
| |
| 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: */ |
