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56 lines
1.6 KiB
C++
56 lines
1.6 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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#include "common/polygon.h"
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namespace Common {
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bool Polygon::contains(int16 x, int16 y) const {
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int yflag0;
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int yflag1;
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bool inside_flag = false;
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unsigned int pt;
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const Point *vtx0 = &_points[_points.size() - 1];
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const Point *vtx1 = &_points[0];
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yflag0 = (vtx0->y >= y);
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for (pt = 0; pt < _points.size(); pt++, vtx1++) {
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yflag1 = (vtx1->y >= y);
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if (yflag0 != yflag1) {
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if (((vtx1->y - y) * (vtx0->x - vtx1->x) >=
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(vtx1->x - x) * (vtx0->y - vtx1->y)) == yflag1) {
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inside_flag = !inside_flag;
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}
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}
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yflag0 = yflag1;
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vtx0 = vtx1;
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}
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return inside_flag;
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}
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} // end of namespace Common
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