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nearest_pt.H

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/*
 * Copyright 2000, Brown University, Providence, RI.
 * 
 *                         All Rights Reserved
 * 
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose other than its incorporation into a
 * commercial product is hereby granted without fee, provided that the
 * above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of Brown University not be used in
 * advertising or publicity pertaining to distribution of the software
 * without specific, written prior permission.
 * 
 * BROWN UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR ANY
 * PARTICULAR PURPOSE.  IN NO EVENT SHALL BROWN UNIVERSITY BE LIABLE FOR
 * ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#ifndef _MLIB_NEAREST_PT_TO_LINE_SEG
#define _MLIB_NEAREST_PT_TO_LINE_SEG

// returns the nearest point on the line defined by (st,en) to the
// point, pt.
//
template <class P>
inline P nearest_pt_to_line(const P &pt, const P &st, const P &en) {
       return st + (en-st)*((en-st)*(pt-st)/(en-st).lengthSqrd());
}

// returns the nearest point on the line segment (st,en) to the
// point, pt.
//
template <class P>
inline P nearest_pt_to_line_seg(const P &pt, const P &st, const P &en) {
       P npt = nearest_pt_to_line(pt, st, en);
       if ((npt - st) * (npt - en) < 0)
          return npt;
       return ((pt-st).lengthSqrd()<(pt-en).lengthSqrd()) ? st : en;
    }

#endif

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