#include "polygon.h"

void Polygon::calc_sides()
{
	for (int i = 0; i < points.size() - 1; i++) {
		sides.push_back(points[i].calc_distance(points[i + 1]));
	}
	sides.push_back(points[points.size() - 1].calc_distance(points[0]));
}

Polygon::Polygon()
{
}

double Polygon::calc_area()
{
	double res=0.0;
	for (int i = 0; i < points.size() - 1; i++) {
		res += points[i].x * points[i + 1].y;
		res += points[i + 1].x * points[i].y;
	}
	res += points[points.size()-1].x * points[0].y;
	res += points[points.size()-1].y * points[0].x;

	return res * 0.5;
}

double Polygon::calc_perimeter()
{
	double res = 0.0;
	for (int i = 0; i < sides.size(); i++)
		res += sides[i];
	return res;
}

void Polygon::name()
{
	cout << "Polygon \n";
}