Common/Geom/SegAlg.h

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//-------------------------------------------------------------------
//  Copyright (c) 2007 Celeritive Technologies, Inc.
//
// 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
//-------------------------------------------------------------------

#pragma once
#ifndef VOLUMILL_SEGALG_H
#define VOLUMILL_SEGALG_H

#include <Geom/Points.h>
#include <Geom/PointAlg.h>

namespace geom
{
   template<class P>
   P projectPointToLine (
      const P& startPt,
      const P& endPt,
      const P& pt)
   {
      VecNd<P::Dim> u (endPt-startPt);
      VecNd<P::Dim> v (pt-startPt);
      double denom = u * u;
      VALIDATE (denom > util::doubleEps * util::doubleEps);
      double param = (u * v) / denom;
      return geom::linComb (1-param, startPt, param, endPt);
   }

   template<class P>
   bool projectPointToSegment (
      const P& startPt,
      const P& endPt,
      const P& pt,
      double tol,
      P* pProjPt = 0,
      double* pParam = 0)
   {
      VecNd<P::Dim> u (endPt-startPt);
      VecNd<P::Dim> v (pt-startPt);
      double uLen = length (u);
      VALIDATE (uLen > util::doubleEps);
      double param = (u * v) / uLen;
      if (param < tol)
      {
         util::assignPtr (pParam, 0.0);
         util::assignPtr (pProjPt, startPt);
         return param > -tol;
      }
      else if (param > uLen-tol)
      {
         util::assignPtr (pParam, 1.0);
         util::assignPtr (pProjPt, endPt);
         return param < uLen + tol;
      }
      param /= uLen;
      util::assignPtr (pParam, param);
      util::assignPtr (pProjPt, geom::linComb (1-param, startPt, param, endPt));
      return true;
   }

   template<class P>
   int getOrientation (
      const P& p0,
      const P& p1,
      const P& pt,
      double tol)
   {
      BOOST_STATIC_ASSERT (P::Dim == 2);
      VecNd<P::Dim> u (p1-p0);
      VecNd<P::Dim> v (pt-p1);
      double uLen = length (u);
      VALIDATE (uLen > util::doubleEps);
      double cross = crossProduct (u, v) / uLen;
      if (cross < -tol)
         return -1;
      else if (cross > tol)
         return 1;
      return 0;
   }
}
#endif

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