quickhull/Line.h

#pragma once

#include <cmath>  // For abs, sqrt

#include "Point.h"

class Line
{
private:
    Point m_from, m_to, m_to_from_origin;

public:
    Line(Point from, Point to) : m_from(from), m_to(to), m_to_from_origin(to - from) {}

    Point from() const
    {
        return m_from;
    }

    Point to() const
    {
        return m_to;
    }

    // Return true if the given point is to the right of this line.
    // False is also returned if the point is directly on the line.
    bool is_point_right(Point other) const
    {
        other -= from();

        // Cross product greater than zero?
        if (m_to_from_origin.x() * other.y() - m_to_from_origin.y() * other.x() > 0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    float distance_to(Point other) const
    {
        float a = from().y() - to().y();
        float b = to().x() - from().x();
        float c = from().x() * to().y() - to().x() * from().y();

        return abs(a * other.x() + b * other.y() + c) / sqrt(a * a + b * b);
    }
};