57 lines
1.8 KiB
Python
57 lines
1.8 KiB
Python
from collections import deque
|
|
from functools import lru_cache
|
|
from itertools import chain
|
|
from typing import Union
|
|
|
|
import numpy as np
|
|
from meshpy import triangle
|
|
from shapely.geometry import MultiPolygon, Polygon
|
|
|
|
|
|
@lru_cache()
|
|
def get_face_indizes(start, length):
|
|
indices = np.tile(np.arange(start, start + length).reshape((-1, 1)), 2).flatten()[1:-1].reshape((length - 1, 2))
|
|
return np.vstack((indices, (indices[-1][-1], indices[0][0])))
|
|
|
|
|
|
def _triangulate_polygon(polygon: Polygon, keep_holes=False):
|
|
vertices = deque()
|
|
segments = deque()
|
|
|
|
offset = 0
|
|
for ring in chain((polygon.exterior,), polygon.interiors):
|
|
new_vertices = np.array(ring.coords)[:-1]
|
|
vertices.append(new_vertices)
|
|
segments.append(get_face_indizes(offset, len(new_vertices)))
|
|
offset += len(new_vertices)
|
|
|
|
info = triangle.MeshInfo()
|
|
info.set_points(np.vstack(vertices))
|
|
info.set_facets(np.vstack(segments).tolist())
|
|
|
|
if not keep_holes:
|
|
holes = np.array(tuple(
|
|
Polygon(ring).representative_point().coords for ring in polygon.interiors
|
|
))
|
|
if holes.size:
|
|
info.set_holes(holes.reshape((holes.shape[0], -1)))
|
|
|
|
mesh = triangle.build(info, quality_meshing=False)
|
|
return np.array(mesh.points), np.array(mesh.elements)
|
|
|
|
|
|
def triangulate_polygon(geometry: Union[Polygon, MultiPolygon], keep_holes=False):
|
|
if isinstance(geometry, Polygon):
|
|
return _triangulate_polygon(geometry, keep_holes=keep_holes)
|
|
|
|
vertices = deque()
|
|
faces = deque()
|
|
|
|
offset = 0
|
|
for polygon in geometry.geoms:
|
|
new_vertices, new_faces = _triangulate_polygon(polygon, keep_holes=keep_holes)
|
|
vertices.append(new_vertices)
|
|
faces.append(new_faces+offset if offset else new_faces)
|
|
offset += len(new_vertices)
|
|
|
|
return np.vstack(vertices), np.vstack(faces)
|