def intersection(axis, coord, triangle):
"""
Returns the intersection (if one exists) between a *triangle*
and the plane based on the *axis* and *coord*.
Also returns a boolean indicating whether or not an
intersection was found.
"""
#create an array for the coordinates
triangle_verts=np.array([], ndmin=3)
triangle_verts.shape =(0, 3, 3)
verts = mesh.getEntAdj(triangle, iBase.Type.vertex)
vert1 = mesh.getVtxCoords(verts[0])
vert2 = mesh.getVtxCoords(verts[1])
vert3 = mesh.getVtxCoords(verts[2])
temp = np.vstack( (vert1, vert2, vert3) )
#insert the coordinates into the array
triangle_verts = np.append(triangle_verts, [temp], axis = 0)
#check for an intersection
line = triangle_plane_intersect(axis, coord, triangle_verts)
#if a line is returned, indicate that we have an intersection
intersect = True if line.size is not 0 else False
return intersect, line
def test_perfect_element_intersection():
# This test tests mesh line annotation where a z=0 slice
# perfectly intersects the top of a hexahedral element with node
# z-coordinates containing both -0 and +0. Before
# https://github.com/yt-project/yt/pull/1437 this test falsely
# yielded three annotation lines, whereas the correct result is four
# corresponding to the four edges of the top hex face.
ds = small_fake_hexahedral_ds()
indices = ds.index.meshes[0].connectivity_indices
coords = ds.index.meshes[0].connectivity_coords
tri_indices = triangulate_indices(indices)
tri_coords = coords[tri_indices]
lines = triangle_plane_intersect(2, 0, tri_coords)
non_zero_lines = 0
for i in range(lines.shape[0]):
norm = np.linalg.norm(lines[i][0] - lines[i][1])
if norm > 1e-8:
non_zero_lines += 1
np.testing.assert_equal(non_zero_lines, 4)
def __call__(self, plot):
plot._axes.hold(True)
ax = plot.data.axis
xax = plot.data.ds.coordinates.x_axis[ax]
yax = plot.data.ds.coordinates.y_axis[ax]
if not hasattr(self.vertices, "in_units"):
vertices = plot.data.pf.arr(self.vertices, "code_length")
else:
vertices = self.vertices
l_cy = triangle_plane_intersect(plot.data.axis, plot.data.coord,
vertices)[:, :, (xax, yax)]
# reformat for conversion to plot coordinates
l_cy = np.rollaxis(l_cy, 0, 3)
# convert all line starting points
l_cy[0] = self.convert_to_plot(plot, l_cy[0])
l_cy[1] = self.convert_to_plot(plot, l_cy[1])
# convert all line ending points
l_cy = np.rollaxis(l_cy, 2, 0)
# create line collection and add it to the plot
lc = matplotlib.collections.LineCollection(l_cy, **self.plot_args)
plot._axes.add_collection(lc)
plot._axes.hold(False)