Line and line collision detection

Ray2.cpp

/**
 * Checks for intersection with another line segment. Touching at
 * endpoints qualifies as intersections.
 *
 * @param math::Ray2 The other line
 *
 * @return TRUE if they intersect, FALSE otherwise.
 * @see http://gamedev.stackexchange.com/questions/26004/how-to-detect-2d-line-on-line-collision
 */
bool Ray2::CheckCollision(const Ray2& Other) const
{
    /**
     * Solve for the intersection point.
     *
     * Derivation:
     *  First line:             y - y1 = m1(x - x1)
     *  Second line:            y - y2 = m2(x - x2)
     *  Equal to each other:    m1x - m1x1 + y1 = m2x - m2x2 + y2
     *  Solve for 'x':          m1x - m2x = -m2x2 + y2 + m1x1 + y1
     *                          x(m1 - m2) = -m2x2 + y2 + m1x1 + y1
     *                          x = (-m2x2 + y2 + m1x1 + y1) / (m1 - m2)
     *  Solve for 'y':          y = m1(x) - m1x1 + y1
     *  Thus (x, y) becomes the intersection point.
     *
     *  Then we must see if (x, y) is in the range of line segments given.
     */

    math::Vector2 Intersect;
    float m1, m2;

    m1 = this->GetSlope();
    m2 = Other.GetSlope();

    // Test for infinite slopes or parallel lines.
    if(this->Start.GetX() == this->End.GetX())
        Intersect.SetX(this->Start.GetX());
    else if(Other.Start.GetX() == Other.End.GetX())
        Intersect.SetX(Other.Start.GetX());
    else if(m1 == m2)
        return false;
    else
        Intersect.SetX((-m2 * Other.Start.GetX() + Other.Start.GetY() + m1 * this->Start.GetX() - this->Start.GetY()) / (m1 - m2));

    Intersect.SetY(m1 * Intersect.GetX() - m1 * this->Start.GetX() + this->Start.GetY());

    return this->OnRay(Intersect) && Other.OnRay(Intersect);
}