#include <math.h>                   /* acos(), M_PI */

#include "Polygon.h"

#define FP_EQUAL(x,y) (fabs((x)-(y)) < 1E-6)

bool Polygon::containsPoint(const Vector & v)
{
    double angle_sum = 0.0;
    for (int i = 0, sz = size(); i < sz; i++)
    {
        Vector v1 = *(*this)[i] - v;
        Vector v2 = *(*this)[(i+1) % sz] - v;
        double cosine = (v1 % v2) / (v1.mag() * v2.mag());
        double angle = acos(cosine);
        angle_sum += angle;
    }
    return FP_EQUAL(angle_sum, 2.0 * M_PI);
}