int Convex(vector<Point> vector_of_points)

{
	int i, j, k;
	int flag = 0;
	double z;

	if (vector_of_points.size() < 3)
		return(0);

	for (i = 0; i < vector_of_points.size(); i++)
	{
		j = (i + 1) % vector_of_points.size();
		k = (i + 2) % vector_of_points.size();
		z = (vector_of_points[j].x - vector_of_points[i].x) * (vector_of_points[k].y - vector_of_points[j].y);
		z -= (vector_of_points[j].y - vector_of_points[i].y) * (vector_of_points[k].x - vector_of_points[j].x);
		if (z < 0)
			flag |= 1;
		else if (z > 0)
			flag |= 2;
		if (flag == 3) {
			cout << "\n\tConcave(вогнутый)";
			return (0);
		}
	}

	if (flag != 0)
		cout << "\n\tConvex(выпуклый)";
	else
		return(0);
}

void inputPoints(vector<Point> &vector_of_points)
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(1, 0, 0);
	glBegin(GL_LINE_LOOP);
	int amount_of_points;
	cout << "amount of points: ";
	cin >> amount_of_points;
	for (int i = 0; i < amount_of_points; i++)
	{
		Point temp;
		cout << "point " << i + 1 << endl;
		cout << "\tinput x  ";
		cin >> temp.x;
		cout << "\tinput y  ";
		cin >> temp.y;
		glVertex2f(temp.x, temp.y);
		vector_of_points.push_back(temp);
	}
	glEnd();
	glFlush();

}