line.py

from decimal import getcontext
from vector import Vector
from util import Util
from error import NoNonzeroElementsFound
from geometrical_representation import GeometricalRepresentation

# Sets the precision in this mathematical context
getcontext().prec = 30

class Line(GeometricalRepresentation):

    def __init__(self, normal_vector=None, constant_term=None):
        super(Line, self).__init__(normal_vector, constant_term, 2)

    def intersection(self, lineB):
        is_parallel = self.is_parallel_to(lineB) 
        is_same = self == lineB

        if is_same:
            return "The lines have infinite intersection points"
        elif is_parallel and not is_same:
            return "The lines have no intersection points"

        try:
            # PyLint is quite angry at me here,
            # but this is a great way to represet the
            # somewhat messy mathematical formular
            # to calculate the intersection point between two lines.
            a = self.normal_vector.coordinates[0]
            b = self.normal_vector.coordinates[1]
            c = lineB.normal_vector.coordinates[0]
            d = lineB.normal_vector.coordinates[1]
            k1 = self.constant_term
            k2 = lineB.constant_term

            denominator = (a * d) - (b * c)
            x = (d * k1 - b * k2) / denominator
            y = (-c * k1 + a * k2) / denominator
            return Vector([x, y])
        except ZeroDivisionError:
            if self == lineB:
                return self
            else:
                return None