| /* |
| Simple DirectMedia Layer |
| Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org> |
| |
| This software is provided 'as-is', without any express or implied |
| warranty. In no event will the authors be held liable for any damages |
| arising from the use of this software. |
| |
| Permission is granted to anyone to use this software for any purpose, |
| including commercial applications, and to alter it and redistribute it |
| freely, subject to the following restrictions: |
| |
| 1. The origin of this software must not be misrepresented; you must not |
| claim that you wrote the original software. If you use this software |
| in a product, an acknowledgment in the product documentation would be |
| appreciated but is not required. |
| 2. Altered source versions must be plainly marked as such, and must not be |
| misrepresented as being the original software. |
| 3. This notice may not be removed or altered from any source distribution. |
| */ |
| #include "../SDL_internal.h" |
| |
| #include "SDL_rect.h" |
| #include "SDL_rect_c.h" |
| |
| SDL_bool |
| SDL_HasIntersection(const SDL_Rect * A, const SDL_Rect * B) |
| { |
| int Amin, Amax, Bmin, Bmax; |
| |
| if (!A) { |
| SDL_InvalidParamError("A"); |
| return SDL_FALSE; |
| } |
| |
| if (!B) { |
| SDL_InvalidParamError("B"); |
| return SDL_FALSE; |
| } |
| |
| /* Special cases for empty rects */ |
| if (SDL_RectEmpty(A) || SDL_RectEmpty(B)) { |
| return SDL_FALSE; |
| } |
| |
| /* 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; |
| |
| if (!A) { |
| SDL_InvalidParamError("A"); |
| return SDL_FALSE; |
| } |
| |
| if (!B) { |
| SDL_InvalidParamError("B"); |
| return SDL_FALSE; |
| } |
| |
| if (!result) { |
| SDL_InvalidParamError("result"); |
| return SDL_FALSE; |
| } |
| |
| /* Special cases for empty rects */ |
| if (SDL_RectEmpty(A) || SDL_RectEmpty(B)) { |
| result->w = 0; |
| result->h = 0; |
| return SDL_FALSE; |
| } |
| |
| /* 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; |
| |
| if (!A) { |
| SDL_InvalidParamError("A"); |
| return; |
| } |
| |
| if (!B) { |
| SDL_InvalidParamError("B"); |
| return; |
| } |
| |
| if (!result) { |
| SDL_InvalidParamError("result"); |
| return; |
| } |
| |
| /* Special cases for empty Rects */ |
| if (SDL_RectEmpty(A)) { |
| if (SDL_RectEmpty(B)) { |
| /* A and B empty */ |
| return; |
| } else { |
| /* A empty, B not empty */ |
| *result = *B; |
| return; |
| } |
| } else { |
| if (SDL_RectEmpty(B)) { |
| /* A not empty, B empty */ |
| *result = *A; |
| return; |
| } |
| } |
| |
| /* 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 union */ |
| 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 (!points) { |
| SDL_InvalidParamError("points"); |
| return SDL_FALSE; |
| } |
| |
| if (count < 1) { |
| SDL_InvalidParamError("count"); |
| return SDL_FALSE; |
| } |
| |
| if (clip) { |
| SDL_bool added = SDL_FALSE; |
| const int clip_minx = clip->x; |
| const int clip_miny = clip->y; |
| const int clip_maxx = clip->x+clip->w-1; |
| const int clip_maxy = clip->y+clip->h-1; |
| |
| /* Special case for empty rectangle */ |
| if (SDL_RectEmpty(clip)) { |
| return SDL_FALSE; |
| } |
| |
| 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) { |
| /* Special case: if no result was requested, we are done */ |
| if (result == NULL) { |
| return SDL_TRUE; |
| } |
| |
| /* First point 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 { |
| /* Special case: if no result was requested, we are done */ |
| if (result == NULL) { |
| return SDL_TRUE; |
| } |
| |
| /* 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 < rect->y) { |
| code |= CODE_TOP; |
| } else if (y >= rect->y + rect->h) { |
| code |= CODE_BOTTOM; |
| } |
| if (x < rect->x) { |
| 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) { |
| SDL_InvalidParamError("rect"); |
| return SDL_FALSE; |
| } |
| |
| if (!X1) { |
| SDL_InvalidParamError("X1"); |
| return SDL_FALSE; |
| } |
| |
| if (!Y1) { |
| SDL_InvalidParamError("Y1"); |
| return SDL_FALSE; |
| } |
| |
| if (!X2) { |
| SDL_InvalidParamError("X2"); |
| return SDL_FALSE; |
| } |
| |
| if (!Y2) { |
| SDL_InvalidParamError("Y2"); |
| return SDL_FALSE; |
| } |
| |
| /* Special case for empty rect */ |
| if (SDL_RectEmpty(rect)) { |
| 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) { |
| /* If this assertion ever fires, here's the static analysis that warned about it: |
| http://buildbot.libsdl.org/sdl-static-analysis/sdl-macosx-static-analysis/sdl-macosx-static-analysis-1101/report-b0d01a.html#EndPath */ |
| SDL_assert(x2 != x1); /* if equal: division by zero. */ |
| x = rectx1; |
| y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1); |
| } else if (outcode2 & CODE_RIGHT) { |
| /* If this assertion ever fires, here's the static analysis that warned about it: |
| http://buildbot.libsdl.org/sdl-static-analysis/sdl-macosx-static-analysis/sdl-macosx-static-analysis-1101/report-39b114.html#EndPath */ |
| SDL_assert(x2 != x1); /* if equal: division by zero. */ |
| 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; |
| } |
| |
| SDL_bool |
| SDL_GetSpanEnclosingRect(int width, int height, |
| int numrects, const SDL_Rect * rects, SDL_Rect *span) |
| { |
| int i; |
| int span_y1, span_y2; |
| int rect_y1, rect_y2; |
| |
| if (width < 1) { |
| SDL_InvalidParamError("width"); |
| return SDL_FALSE; |
| } |
| |
| if (height < 1) { |
| SDL_InvalidParamError("height"); |
| return SDL_FALSE; |
| } |
| |
| if (!rects) { |
| SDL_InvalidParamError("rects"); |
| return SDL_FALSE; |
| } |
| |
| if (!span) { |
| SDL_InvalidParamError("span"); |
| return SDL_FALSE; |
| } |
| |
| if (numrects < 1) { |
| SDL_InvalidParamError("numrects"); |
| return SDL_FALSE; |
| } |
| |
| /* Initialize to empty rect */ |
| span_y1 = height; |
| span_y2 = 0; |
| |
| for (i = 0; i < numrects; ++i) { |
| rect_y1 = rects[i].y; |
| rect_y2 = rect_y1 + rects[i].h; |
| |
| /* Clip out of bounds rectangles, and expand span rect */ |
| if (rect_y1 < 0) { |
| span_y1 = 0; |
| } else if (rect_y1 < span_y1) { |
| span_y1 = rect_y1; |
| } |
| if (rect_y2 > height) { |
| span_y2 = height; |
| } else if (rect_y2 > span_y2) { |
| span_y2 = rect_y2; |
| } |
| } |
| if (span_y2 > span_y1) { |
| span->x = 0; |
| span->y = span_y1; |
| span->w = width; |
| span->h = (span_y2 - span_y1); |
| return SDL_TRUE; |
| } |
| return SDL_FALSE; |
| } |
| |
| /* vi: set ts=4 sw=4 expandtab: */ |
