# coding: utf-8
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"""This module provides conversion functions between OpenGL and numpy types.
"""
__authors__ = ["T. Vincent"]
__license__ = "MIT"
__date__ = "10/01/2017"
import numpy
from OpenGL.constants import BYTE_SIZES as _BYTE_SIZES
from OpenGL.constants import ARRAY_TO_GL_TYPE_MAPPING as _ARRAY_TO_GL_TYPE_MAPPING
[docs]def sizeofGLType(type_):
"""Returns the size in bytes of an element of type `type_`"""
return _BYTE_SIZES[type_]
[docs]def isSupportedGLType(type_):
"""Test if a numpy type or dtype can be converted to a GL type."""
return numpy.dtype(type_).char in _ARRAY_TO_GL_TYPE_MAPPING
[docs]def numpyToGLType(type_):
"""Returns the GL type corresponding the provided numpy type or dtype."""
return _ARRAY_TO_GL_TYPE_MAPPING[numpy.dtype(type_).char]
def segmentTrianglesIntersection(segment, triangles):
"""Check for segment/triangles intersection.
This is based on signed tetrahedron volume comparison.
See A. Kensler, A., Shirley, P.
Optimizing Ray-Triangle Intersection via Automated Search.
Symposium on Interactive Ray Tracing, vol. 0, p33-38 (2006)
:param numpy.ndarray segment:
Segment end points as a 2x3 array of coordinates
:param numpy.ndarray triangles:
Nx3x3 array of triangles
:return: (triangle indices, segment parameter, barycentric coord)
Indices of intersected triangles, "depth" along the segment
of the intersection point and barycentric coordinates of intersection
point in the triangle.
:rtype: List[numpy.ndarray]
"""
# TODO triangles from vertices + indices
# TODO early rejection? e.g., check segment bbox vs triangle bbox
segment = numpy.asarray(segment)
assert segment.ndim == 2
assert segment.shape == (2, 3)
triangles = numpy.asarray(triangles)
assert triangles.ndim == 3
assert triangles.shape[1] == 3
# Test line/triangles intersection
d = segment[1] - segment[0]
t0s0 = segment[0] - triangles[:, 0, :]
edge01 = triangles[:, 1, :] - triangles[:, 0, :]
edge02 = triangles[:, 2, :] - triangles[:, 0, :]
dCrossEdge02 = numpy.cross(d, edge02)
t0s0CrossEdge01 = numpy.cross(t0s0, edge01)
volume = numpy.sum(dCrossEdge02 * edge01, axis=1)
del edge01
subVolumes = numpy.empty((len(triangles), 3), dtype=triangles.dtype)
subVolumes[:, 1] = numpy.sum(dCrossEdge02 * t0s0, axis=1)
del dCrossEdge02
subVolumes[:, 2] = numpy.sum(t0s0CrossEdge01 * d, axis=1)
subVolumes[:, 0] = volume - subVolumes[:, 1] - subVolumes[:, 2]
intersect = numpy.logical_or(
numpy.all(subVolumes >= 0., axis=1), # All positive
numpy.all(subVolumes <= 0., axis=1)) # All negative
intersect = numpy.where(intersect)[0] # Indices of intersected triangles
# Get barycentric coordinates
barycentric = subVolumes[intersect] / volume[intersect].reshape(-1, 1)
del subVolumes
# Test segment/triangles intersection
volAlpha = numpy.sum(t0s0CrossEdge01[intersect] * edge02[intersect], axis=1)
t = volAlpha / volume[intersect] # segment parameter of intersected triangles
del t0s0CrossEdge01
del edge02
del volAlpha
del volume
inSegmentMask = numpy.logical_and(t >= 0., t <= 1.)
intersect = intersect[inSegmentMask]
t = t[inSegmentMask]
barycentric = barycentric[inSegmentMask]
# Sort intersecting triangles by t
indices = numpy.argsort(t)
return intersect[indices], t[indices], barycentric[indices]
