# coding=utf-8
"""2D Line Segment"""
from __future__ import division
import math
from .pointvector import Vector2D, Point2D
from ._1d import Base1DIn2D
from ..intersection2d import closest_point2d_between_line2d, intersect_line2d, \
intersect_line_segment2d
[docs]
class LineSegment2D(Base1DIn2D):
"""2D line segment object.
Args:
p: A Point2D representing the first point of the line segment.
v: A Vector2D representing the vector to the second point.
Properties:
* p
* v
* p1
* p2
* min
* max
* center
* midpoint
* endpoints
* length
* vertices
"""
__slots__ = ()
def __init__(self, p, v):
"""Initialize LineSegment2D."""
Base1DIn2D.__init__(self, p, v)
[docs]
@classmethod
def from_end_points(cls, p1, p2):
"""Initialize a line segment from a start point and and end point.
Args:
p1: A Point2D representing the first point of the line segment.
p2: A Point2D representing the second point of the line segment.
"""
v = p2 - p1
return cls(p1, Vector2D(v.x, v.y))
[docs]
@classmethod
def from_sdl(cls, s, d, length):
"""Initialize a line segment from a start point, direction, and length.
Args:
s: A Point2D representing the start point of the line segment.
d: A Vector2D representing the direction of the line segment.
length: A number representing the length of the line segment.
"""
return cls(s, d * length / d.magnitude)
[docs]
@classmethod
def from_array(cls, line_array):
""" Create a LineSegment2D from a nested array of two endpoint coordinates.
Args:
line_array: Nested tuples ((pt1.x, pt1.y), (pt2.x, pt2.y)), where
pt1 and pt2 represent the endpoints of the line segment.
"""
return LineSegment2D.from_end_points(*tuple(Point2D(*pt) for pt in line_array))
@property
def p1(self):
"""First point (same as p)."""
return self.p
@property
def p2(self):
"""Second point."""
return Point2D(self.p.x + self.v.x, self.p.y + self.v.y)
@property
def midpoint(self):
"""Midpoint."""
return self.point_at(0.5)
@property
def endpoints(self):
"""Tuple of endpoints """
return (self.p1, self.p2)
@property
def length(self):
"""The length of the line segment."""
return self.v.magnitude
@property
def vertices(self):
"""Tuple of both vertices in this object."""
return (self.p1, self.p2)
[docs]
def is_equivalent(self, other, tolerance):
"""Boolean noting equivalence (within tolerance) between this line and another.
The order of the line points do not matter for equivalence to be true.
Args:
other: LineSegment2D for comparison.
tolerance: float representing point equivalence.
Returns:
True if equivalent else False
"""
tol = tolerance
return (
self.p1.is_equivalent(other.p1, tol) and self.p2.is_equivalent(other.p2, tol)
) or (
self.p1.is_equivalent(other.p2, tol) and self.p2.is_equivalent(other.p1, tol)
)
[docs]
def flip(self):
"""Get a copy of this line segment that is flipped."""
return LineSegment2D(self.p2, self.v.reverse())
[docs]
def move(self, moving_vec):
"""Get a line segment that has been moved along a vector.
Args:
moving_vec: A Vector2D with the direction and distance to move the ray.
"""
return LineSegment2D(self.p.move(moving_vec), self.v)
[docs]
def rotate(self, angle, origin):
"""Get a line segment that is rotated counterclockwise by a certain angle.
Args:
angle: An angle for rotation in radians.
origin: A Point2D for the origin around which the line segment will
be rotated.
"""
return LineSegment2D(self.p.rotate(angle, origin), self.v.rotate(angle))
[docs]
def reflect(self, normal, origin):
"""Get a line segment reflected across a plane with the input normal and origin.
Args:
normal: A Vector2D representing the normal vector for the plane across
which the line segment will be reflected. THIS VECTOR MUST BE NORMALIZED.
origin: A Point2D representing the origin from which to reflect.
"""
return LineSegment2D(self.p.reflect(normal, origin), self.v.reflect(normal))
[docs]
def scale(self, factor, origin=None):
"""Scale a line segment by a factor from an origin point.
Args:
factor: A number representing how much the line segment should be scaled.
origin: A Point2D representing the origin from which to scale.
If None, it will be scaled from the World origin (0, 0).
"""
return LineSegment2D(self.p.scale(factor, origin), self.v * factor)
[docs]
def offset(self, distance):
"""Offset the line segment by a given distance.
Args:
distance: The distance that the line segment will be offset. Both positive
and negative values are accepted with positive values being offset
to the left of the line and negative values being offset to the
right of the line (starting from LineSegment.p and looking
in the direction of LineSegment.v).
"""
if distance == 0:
return self
move_vec = self.v.rotate(math.pi / 2).normalize() * distance
return LineSegment2D(self.p.move(move_vec), self.v)
[docs]
def subdivide(self, distances):
"""Get Point2D values along the line that subdivide it based on input distances.
Args:
distances: A list of distances along the line at which to subdivide it.
This can also be a single number that will be repeated until the
end of the line.
"""
if isinstance(distances, (float, int)):
distances = [distances]
line_length = self.length
dist = distances[0]
index = 0
sub_pts = [self.p]
while dist < line_length:
sub_pts.append(self.point_at_length(dist))
if index < len(distances) - 1:
index += 1
dist += distances[index]
sub_pts.append(self.p2)
return sub_pts
[docs]
def subdivide_evenly(self, number):
"""Get Point2D values along the line that divide it into evenly-spaced segments.
Args:
number: The number of segments into which the line will be divided.
"""
interval = 1 / number
parameter = interval
sub_pts = [self.p]
while parameter <= 1:
sub_pts.append(self.point_at(parameter))
parameter += interval
return sub_pts
[docs]
def point_at(self, parameter):
"""Get a point at a given fraction along the line segment.
Args:
parameter: The fraction between the start and end point where the
desired point lies. For example, 0.5 will yield the midpoint.
"""
return self.p + self.v * parameter
[docs]
def point_at_length(self, length):
"""Get a point at a given distance along the line segment.
Args:
length: The distance along the line from the start point where the
desired point lies.
"""
return self.p + self.v * (length / self.length)
[docs]
def intersect_line_ray(self, line_ray):
"""Get the intersection between this object and another Ray2 or LineSegment2D.
Args:
line_ray: Another LineSegment2D or Ray2D or to intersect.
Returns:
Point2D of intersection if it exists. None if no intersection exists.
"""
if isinstance(line_ray, LineSegment2D):
return intersect_line_segment2d(self, line_ray)
return intersect_line2d(self, line_ray)
[docs]
def closest_points_between_line(self, line):
"""Get the two closest Point2D between this object to another LineSegment2D.
Note that the line segments should not intersect for the result to be valid.
Args:
line: A LineSegment2D object to which the closest points
will be computed.
Returns:
Two Point2D objects representing
1) The closest point on this object to the input line.
2) The closest point on the input line to this object.
"""
dist, pts = closest_point2d_between_line2d(self, line)
return pts
[docs]
def distance_to_line(self, line):
"""Get the minimum distance between this object and the input LineSegment2D.
Note that the line segments should not intersect for the result to be valid.
Args:
line: A LineSegment2D object to which the minimum distance will be computed.
Returns:
The minimum distance to the input line.
"""
dist, pts = closest_point2d_between_line2d(self, line)
return dist
[docs]
def to_dict(self):
"""Get LineSegment2D as a dictionary."""
base = Base1DIn2D.to_dict(self)
base['type'] = 'LineSegment2D'
return base
[docs]
def to_array(self):
""" A nested list representing the two line endpoint coordinates."""
return (self.p1.to_array(), self.p2.to_array())
def _u_in(self, u):
return u >= 0.0 and u <= 1.0
def __abs__(self):
return abs(self.v)
def __copy__(self):
return LineSegment2D(self.p, self.v)
def __key(self):
"""A tuple based on the object properties, useful for hashing."""
return (hash(self.p), hash(self.v))
def __hash__(self):
return hash(self.__key())
def __eq__(self, other):
return isinstance(other, LineSegment2D) and self.__key() == other.__key()
def __repr__(self):
return 'LineSegment2D (<%.2f, %.2f> to <%.2f, %.2f>)' % \
(self.p.x, self.p.y, self.p.x + self.v.x, self.p.y + self.v.y)