def to_star_contour_vertices(points: Sequence[Point[Scalar]],
context: Context) -> Sequence[Point[Scalar]]:
centroid = context.multipoint_centroid(context.multipoint_cls(points))
contour_cls, region_centroid_constructor, orienteer = (
context.contour_cls, context.region_centroid,
context.angle_orientation)
result, prev_size = points, len(points) + 1
while 2 < len(result) < prev_size:
prev_size = len(result)
result = [
deque(candidates, maxlen=1)[0][1]
for _, candidates in groupby(sorted(
(_to_segment_angle(centroid, point), point)
for point in result),
key=itemgetter(0))
]
if len(result) > 2:
centroid = region_centroid_constructor(contour_cls(result))
index = 0
while max(index, 2) < len(result):
if not angle_contains_point(result[index], result[index - 1],
result[(index + 1) % len(result)],
centroid, orienteer):
del result[index]
index += 1
compress_contour(result, orienteer)
return result
def intersect_segments(first: Segment,
second: Segment,
context: Context) -> Union_[Empty, Multipoint, Segment]:
relation = context.segments_relation(first, second)
if relation is Relation.DISJOINT:
return context.empty
elif relation is Relation.TOUCH or relation is Relation.CROSS:
return context.multipoint_cls([context.segments_intersection(first,
second)])
else:
return (first
if relation is Relation.EQUAL or relation is Relation.COMPONENT
else
(second
if relation is Relation.COMPOSITE
else _intersect_segments_overlap(first, second, context)))
def unpack_points(points: Sequence[Point], context: Context
) -> Union[Empty, Multipoint]:
return context.multipoint_cls(points) if points else context.empty
