/*
 * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
 * http://code.google.com/p/poly2tri/
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of Poly2Tri nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef UTILS_H
#define UTILS_H

// Otherwise #defines like M_PI are undeclared under Visual Studio
#define _USE_MATH_DEFINES

#include <exception>
#include <math.h>

namespace p2t {
const double    PI_3div4    = 3 * M_PI / 4;
const double    PI_div2     = 1.57079632679489661923;
const double    EPSILON     = 1e-12;

enum Orientation {
    CW, CCW, COLLINEAR
};

/**
 * Forumla to calculate signed area<br>
 * Positive if CCW<br>
 * Negative if CW<br>
 * 0 if collinear<br>
 * <pre>
 * A[P1,P2,P3]  =  (x1*y2 - y1*x2) + (x2*y3 - y2*x3) + (x3*y1 - y3*x1)
 *              =  (x1-x3)*(y2-y3) - (y1-y3)*(x2-x3)
 * </pre>
 */
Orientation Orient2d( Point& pa, Point& pb, Point& pc )
{
    double  detleft     = (pa.x - pc.x) * (pb.y - pc.y);
    double  detright    = (pa.y - pc.y) * (pb.x - pc.x);
    double  val = detleft - detright;

    if( val > -EPSILON && val < EPSILON )
    {
        return COLLINEAR;
    }
    else if( val > 0 )
    {
        return CCW;
    }

    return CW;
}


/*
 *  bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
 *  {
 *  double pdx = pd.x;
 *  double pdy = pd.y;
 *  double adx = pa.x - pdx;
 *  double ady = pa.y - pdy;
 *  double bdx = pb.x - pdx;
 *  double bdy = pb.y - pdy;
 *
 *  double adxbdy = adx * bdy;
 *  double bdxady = bdx * ady;
 *  double oabd = adxbdy - bdxady;
 *
 *  if (oabd <= EPSILON) {
 *   return false;
 *  }
 *
 *  double cdx = pc.x - pdx;
 *  double cdy = pc.y - pdy;
 *
 *  double cdxady = cdx * ady;
 *  double adxcdy = adx * cdy;
 *  double ocad = cdxady - adxcdy;
 *
 *  if (ocad <= EPSILON) {
 *   return false;
 *  }
 *
 *  return true;
 *  }
 *
 */

bool InScanArea( Point& pa, Point& pb, Point& pc, Point& pd )
{
    double oadb = (pa.x - pb.x) * (pd.y - pb.y) - (pd.x - pb.x) * (pa.y - pb.y);

    if( oadb >= -EPSILON )
    {
        return false;
    }

    double oadc = (pa.x - pc.x) * (pd.y - pc.y) - (pd.x - pc.x) * (pa.y - pc.y);

    if( oadc <= EPSILON )
    {
        return false;
    }

    return true;
}
}

#endif
