ECON / lib /common /libmesh /triangle_hash.pyx
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# distutils: language=c++
import numpy as np
cimport cython
cimport numpy as np
from libc.math cimport ceil, floor
from libcpp.vector cimport vector
cdef class TriangleHash:
cdef vector[vector[int]] spatial_hash
cdef int resolution
def __cinit__(self, double[:, :, :] triangles, int resolution):
self.spatial_hash.resize(resolution * resolution)
self.resolution = resolution
self._build_hash(triangles)
@cython.boundscheck(False) # Deactivate bounds checking
@cython.wraparound(False) # Deactivate negative indexing.
cdef int _build_hash(self, double[:, :, :] triangles):
assert(triangles.shape[1] == 3)
assert(triangles.shape[2] == 2)
cdef int n_tri = triangles.shape[0]
cdef int bbox_min[2]
cdef int bbox_max[2]
cdef int i_tri, j, x, y
cdef int spatial_idx
for i_tri in range(n_tri):
# Compute bounding box
for j in range(2):
bbox_min[j] = <int> min(
triangles[i_tri, 0, j], triangles[i_tri, 1, j], triangles[i_tri, 2, j]
)
bbox_max[j] = <int> max(
triangles[i_tri, 0, j], triangles[i_tri, 1, j], triangles[i_tri, 2, j]
)
bbox_min[j] = min(max(bbox_min[j], 0), self.resolution - 1)
bbox_max[j] = min(max(bbox_max[j], 0), self.resolution - 1)
# Find all voxels where bounding box intersects
for x in range(bbox_min[0], bbox_max[0] + 1):
for y in range(bbox_min[1], bbox_max[1] + 1):
spatial_idx = self.resolution * x + y
self.spatial_hash[spatial_idx].push_back(i_tri)
@cython.boundscheck(False) # Deactivate bounds checking
@cython.wraparound(False) # Deactivate negative indexing.
cpdef query(self, double[:, :] points):
assert(points.shape[1] == 2)
cdef int n_points = points.shape[0]
cdef vector[int] points_indices
cdef vector[int] tri_indices
# cdef int[:] points_indices_np
# cdef int[:] tri_indices_np
cdef int i_point, k, x, y
cdef int spatial_idx
for i_point in range(n_points):
x = int(points[i_point, 0])
y = int(points[i_point, 1])
if not (0 <= x < self.resolution and 0 <= y < self.resolution):
continue
spatial_idx = self.resolution * x + y
for i_tri in self.spatial_hash[spatial_idx]:
points_indices.push_back(i_point)
tri_indices.push_back(i_tri)
points_indices_np = np.zeros(points_indices.size(), dtype=np.int32)
tri_indices_np = np.zeros(tri_indices.size(), dtype=np.int32)
cdef int[:] points_indices_view = points_indices_np
cdef int[:] tri_indices_view = tri_indices_np
for k in range(points_indices.size()):
points_indices_view[k] = points_indices[k]
for k in range(tri_indices.size()):
tri_indices_view[k] = tri_indices[k]
return points_indices_np, tri_indices_np