c++ Sorting 2D Points clockwise

Question

i wrote a program to arrange points on a graph in clockwise manner from 12 o\'clock such that, a vector containing these points is sorted in that order. I am using atan2 to ge

Answer 1

You don't need the adjustment. atan2 will give you the angle from positive direction of x axis, counterclockwise in range of -PI to PI.

Firstly, to make the starting point positive direction of y axis, let me give parameter to atan2 as if negative direction of y axis is positive direction of x axis and positive direction of x axis is positive direction is y axis.

Then, this will make the angle counterclockwise, so negate the angle in order to reverse the order.

double get_clockwise_angle(const Point& p)
{   
    double angle = 0.0;
    int quadrant = get_quadrant(p);

    /*making sure the quadrants are correct*/
    cout << "Point: " << p << " is on the " << quadrant << " quadrant" << endl;

    /*calculate angle and return it*/
    angle = -atan2(p.x,-p.y);
    return angle;
}