347 lines
11 KiB
Python
347 lines
11 KiB
Python
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"""
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Ray queries using the pyembree package with the
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API wrapped to match our native raytracer.
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"""
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import numpy as np
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from copy import deepcopy
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from pyembree import __version__ as _ver
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from pyembree import rtcore_scene
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from pyembree.mesh_construction import TriangleMesh
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from pkg_resources import parse_version
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from .ray_util import contains_points
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from .. import util
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from .. import caching
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from .. import intersections
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from ..constants import log_time
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# the factor of geometry.scale to offset a ray from a triangle
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# to reliably not hit its origin triangle
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_ray_offset_factor = 1e-4
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# we want to clip our offset to a sane distance
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_ray_offset_floor = 1e-8
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# see if we're using a newer version of the pyembree wrapper
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_embree_new = parse_version(_ver) >= parse_version('0.1.4')
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# both old and new versions require exact but different type
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_embree_dtype = [np.float64, np.float32][int(_embree_new)]
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class RayMeshIntersector(object):
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def __init__(self,
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geometry,
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scale_to_box=True):
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"""
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Do ray- mesh queries.
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Parameters
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-------------
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geometry : Trimesh object
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Mesh to do ray tests on
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scale_to_box : bool
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If true, will scale mesh to approximate
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unit cube to avoid problems with extreme
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large or small meshes.
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"""
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self.mesh = geometry
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self._scale_to_box = scale_to_box
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self._cache = caching.Cache(id_function=self.mesh.crc)
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@property
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def _scale(self):
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"""
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Scaling factor for precision.
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"""
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if self._scale_to_box:
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# scale vertices to approximately a cube to help with
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# numerical issues at very large/small scales
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scale = 100.0 / self.mesh.scale
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else:
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scale = 1.0
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return scale
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@caching.cache_decorator
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def _scene(self):
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"""
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A cached version of the pyembree scene.
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"""
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return _EmbreeWrap(vertices=self.mesh.vertices,
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faces=self.mesh.faces,
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scale=self._scale)
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def intersects_location(self,
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ray_origins,
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ray_directions,
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multiple_hits=True):
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"""
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Return the location of where a ray hits a surface.
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Parameters
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----------
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ray_origins : (n, 3) float
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Origins of rays
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ray_directions : (n, 3) float
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Direction (vector) of rays
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Returns
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---------
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locations : (m) sequence of (p, 3) float
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Intersection points
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index_ray : (m,) int
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Indexes of ray
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index_tri : (m,) int
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Indexes of mesh.faces
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"""
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(index_tri,
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index_ray,
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locations) = self.intersects_id(
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ray_origins=ray_origins,
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ray_directions=ray_directions,
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multiple_hits=multiple_hits,
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return_locations=True)
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return locations, index_ray, index_tri
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@log_time
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def intersects_id(self,
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ray_origins,
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ray_directions,
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multiple_hits=True,
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max_hits=20,
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return_locations=False):
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"""
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Find the triangles hit by a list of rays, including
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optionally multiple hits along a single ray.
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Parameters
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----------
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ray_origins : (n, 3) float
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Origins of rays
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ray_directions : (n, 3) float
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Direction (vector) of rays
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multiple_hits : bool
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If True will return every hit along the ray
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If False will only return first hit
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max_hits : int
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Maximum number of hits per ray
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return_locations : bool
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Should we return hit locations or not
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Returns
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---------
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index_tri : (m,) int
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Indexes of mesh.faces
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index_ray : (m,) int
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Indexes of ray
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locations : (m) sequence of (p, 3) float
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Intersection points, only returned if return_locations
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"""
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# make sure input is _dtype for embree
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ray_origins = np.asanyarray(
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deepcopy(ray_origins),
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dtype=np.float64)
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ray_directions = np.asanyarray(ray_directions,
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dtype=np.float64)
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ray_directions = util.unitize(ray_directions)
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# since we are constructing all hits, save them to a deque then
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# stack into (depth, len(rays)) at the end
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result_triangle = []
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result_ray_idx = []
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result_locations = []
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# the mask for which rays are still active
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current = np.ones(len(ray_origins), dtype=np.bool)
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if multiple_hits or return_locations:
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# how much to offset ray to transport to the other side of face
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distance = np.clip(_ray_offset_factor * self._scale,
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_ray_offset_floor,
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np.inf)
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ray_offsets = ray_directions * distance
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# grab the planes from triangles
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plane_origins = self.mesh.triangles[:, 0, :]
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plane_normals = self.mesh.face_normals
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# use a for loop rather than a while to ensure this exits
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# if a ray is offset from a triangle and then is reported
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# hitting itself this could get stuck on that one triangle
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for query_depth in range(max_hits):
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# run the pyembree query
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# if you set output=1 it will calculate distance along
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# ray, which is bizzarely slower than our calculation
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query = self._scene.run(
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ray_origins[current],
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ray_directions[current])
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# basically we need to reduce the rays to the ones that hit
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# something
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hit = query != -1
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# which triangle indexes were hit
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hit_triangle = query[hit]
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# eliminate rays that didn't hit anything from future queries
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current_index = np.nonzero(current)[0]
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current_index_no_hit = current_index[np.logical_not(hit)]
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current_index_hit = current_index[hit]
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current[current_index_no_hit] = False
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# append the triangle and ray index to the results
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result_triangle.append(hit_triangle)
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result_ray_idx.append(current_index_hit)
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# if we don't need all of the hits, return the first one
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if ((not multiple_hits and
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not return_locations) or
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not hit.any()):
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break
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# find the location of where the ray hit the triangle plane
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new_origins, valid = intersections.planes_lines(
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plane_origins=plane_origins[hit_triangle],
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plane_normals=plane_normals[hit_triangle],
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line_origins=ray_origins[current],
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line_directions=ray_directions[current])
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if not valid.all():
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# since a plane intersection was invalid we have to go back and
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# fix some stuff, we pop the ray index and triangle index,
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# apply the valid mask then append it right back to keep our
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# indexes intact
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result_ray_idx.append(result_ray_idx.pop()[valid])
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result_triangle.append(result_triangle.pop()[valid])
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# update the current rays to reflect that we couldn't find a
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# new origin
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current[current_index_hit[np.logical_not(valid)]] = False
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# since we had to find the intersection point anyway we save it
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# even if we're not going to return it
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result_locations.extend(new_origins)
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if multiple_hits:
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# move the ray origin to the other side of the triangle
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ray_origins[current] = new_origins + ray_offsets[current]
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else:
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break
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# stack the deques into nice 1D numpy arrays
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index_tri = np.hstack(result_triangle)
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index_ray = np.hstack(result_ray_idx)
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if return_locations:
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locations = (
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np.zeros((0, 3), float) if len(result_locations) == 0
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else np.array(result_locations))
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return index_tri, index_ray, locations
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return index_tri, index_ray
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@log_time
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def intersects_first(self,
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ray_origins,
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ray_directions):
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"""
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Find the index of the first triangle a ray hits.
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Parameters
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----------
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ray_origins : (n, 3) float
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Origins of rays
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ray_directions : (n, 3) float
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Direction (vector) of rays
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Returns
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----------
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triangle_index : (n,) int
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Index of triangle ray hit, or -1 if not hit
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"""
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ray_origins = np.asanyarray(deepcopy(ray_origins))
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ray_directions = np.asanyarray(ray_directions)
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triangle_index = self._scene.run(ray_origins,
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ray_directions)
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return triangle_index
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def intersects_any(self,
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ray_origins,
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ray_directions):
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"""
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Check if a list of rays hits the surface.
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Parameters
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-----------
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ray_origins : (n, 3) float
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Origins of rays
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ray_directions : (n, 3) float
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Direction (vector) of rays
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Returns
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----------
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hit : (n,) bool
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Did each ray hit the surface
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"""
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first = self.intersects_first(ray_origins=ray_origins,
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ray_directions=ray_directions)
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hit = first != -1
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return hit
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def contains_points(self, points):
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"""
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Check if a mesh contains a list of points, using ray tests.
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If the point is on the surface of the mesh, behavior is undefined.
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Parameters
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---------
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points: (n, 3) points in space
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Returns
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---------
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contains: (n,) bool
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Whether point is inside mesh or not
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"""
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return contains_points(self, points)
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class _EmbreeWrap(object):
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"""
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A light wrapper for PyEmbree scene objects which
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allows queries to be scaled to help with precision
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issues, as well as selecting the correct dtypes.
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"""
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def __init__(self, vertices, faces, scale):
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scaled = np.array(vertices,
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dtype=np.float64)
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self.origin = scaled.min(axis=0)
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self.scale = float(scale)
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scaled = (scaled - self.origin) * self.scale
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self.scene = rtcore_scene.EmbreeScene()
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# assign the geometry to the scene
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TriangleMesh(
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scene=self.scene,
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vertices=scaled.astype(_embree_dtype),
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indices=faces.view(np.ndarray).astype(np.int32))
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def run(self, origins, normals, **kwargs):
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scaled = (np.array(origins,
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dtype=np.float64) - self.origin) * self.scale
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return self.scene.run(scaled.astype(_embree_dtype),
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normals.astype(_embree_dtype),
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**kwargs)
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