52 lines
1.2 KiB
C++
52 lines
1.2 KiB
C++
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// This file is part of libigl, a simple c++ geometry processing library.
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//
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// Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla Public License
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// v. 2.0. If a copy of the MPL was not distributed with this file, You can
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// obtain one at http://mozilla.org/MPL/2.0/.
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#include "point_in_poly.h"
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bool IGL_INLINE igl::point_in_poly( const std::vector<std::vector<unsigned int > >&poly,
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const unsigned int xt,
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const unsigned int yt)
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{
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int npoints= poly.size();
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unsigned int xnew,ynew;
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unsigned int xold,yold;
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unsigned int x1,y1;
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unsigned int x2,y2;
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int i;
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int inside=0;
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if (npoints < 3) {
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return(0);
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}
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xold=poly[npoints-1][0];
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yold=poly[npoints-1][1];
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for (i=0 ; i < npoints ; i++) {
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xnew=poly[i][0];
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ynew=poly[i][1];
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if (xnew > xold) {
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x1=xold;
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x2=xnew;
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y1=yold;
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y2=ynew;
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}
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else {
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x1=xnew;
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x2=xold;
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y1=ynew;
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y2=yold;
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}
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if ((xnew < xt) == (xt <= xold) /* edge "open" at one end */
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&& ((long)yt-(long)y1)*(long)(x2-x1)
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< ((long)y2-(long)y1)*(long)(xt-x1)) {
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inside=!inside;
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}
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xold=xnew;
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yold=ynew;
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}
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return (inside != 0);
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}
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