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Fix triangulation issue for polygons with many holes

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This commit is contained in:
Grant Sanderson
2021-02-02 15:35:03 -08:00
parent dcffbe21d5
commit 729dae1376
2 changed files with 28 additions and 130 deletions
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30
manimlib/mobject/svg/svg_mobject.py
View File

@ -23,35 +23,6 @@ from manimlib.utils.directories import get_mobject_data_dir
from manimlib.utils.images import get_full_vector_image_path
def check_and_fix_percent_bug(sym):
# This is an ugly patch addressing something which should be
# addressed at a deeper level.
# The svg path for percent symbols have a known bug, so this
# checks if the symbol is (probably) a percentage sign, and
# splits it so that it's displayed properly.
if len(sym.get_points()) not in [315, 324, 372, 468, 483] or len(sym.get_subpaths()) != 4:
return
sym = sym.family_members_with_points()[0]
new_sym = VMobject()
path_lengths = [len(path) for path in sym.get_subpaths()]
sym_points = sym.get_points()
if len(sym_points) in [315, 324, 372]:
n = sum(path_lengths[:2])
p1 = sym_points[:n]
p2 = sym_points[n:]
elif len(sym_points) in [468, 483]:
p1 = np.vstack([
sym_points[:path_lengths[0]],
sym_points[-path_lengths[3]:]
])
p2 = sym_points[path_lengths[0]:sum(path_lengths[:3])]
sym.set_points(p1)
new_sym.set_points(p2)
sym.add(new_sym)
sym.refresh_triangulation()
def string_to_numbers(num_string):
num_string = num_string.replace("-", ",-")
num_string = num_string.replace("e,-", "e-")
@ -379,7 +350,6 @@ class VMobjectFromSVGPathstring(VMobject):
self.stretch(-1, 1, about_point=ORIGIN)
# Save to a file for future use
np.save(points_filepath, self.get_points())
check_and_fix_percent_bug(self)
def get_commands_and_coord_strings(self):
all_commands = list(self.get_command_to_function_map().keys())

128
manimlib/utils/space_ops.py
View File

@ -349,29 +349,41 @@ def norm_squared(v):
# TODO, fails for polygons drawn over themselves
def earclip_triangulation(verts, rings):
"""
Returns a list of indices giving a triangulation
of a polygon, potentially with holes
- verts is an NxM numpy array of points with M > 2
- rings is a list of indices indicating where
the ends of new paths are
"""
n = len(verts)
# Establish where loop indices should be connected
loop_connections = dict()
for e0, e1 in zip(rings, rings[1:]):
temp_i = e0
# Find closet point in the first ring (j) to
# the first index of this ring (i)
norms = np.array([
[j, norm_squared(verts[temp_i] - verts[j])]
for j in range(0, rings[0])
if j not in loop_connections
])
j = int(norms[norms[:, 1].argmin()][0])
# Find i closest to this j
norms = np.array([
[i, norm_squared(verts[i] - verts[j])]
for i in range(e0, e1)
# for e0, e1 in zip(rings, rings[1:]):
e0 = rings[0]
for e1 in rings[1:]:
# Find closet pair of points with the first
# coming from the current ring, and the second
# coming from the next ring
index_pairs = [
(i, j)
for i in range(0, e0)
for j in range(e0, e1)
if i not in loop_connections
])
i = int(norms[norms[:, 1].argmin()][0])
if j not in loop_connections
]
i, j = index_pairs[np.argmin([
norm_squared(verts[i] - verts[j])
for i, j in index_pairs
])]
# Connect the polygon at these points so that
# it's treated as a single highly-convex ring
loop_connections[i] = j
loop_connections[j] = i
e0 = e1
# Setup linked list
after = []
@ -397,87 +409,3 @@ def earclip_triangulation(verts, rings):
meta_indices = earcut(verts[indices, :2], [len(indices)])
return [indices[mi] for mi in meta_indices]
def old_earclip_triangulation(verts, rings, orientation):
n = len(verts)
assert(n in rings)
result = []
# Establish where loop indices should be connected
loop_connections = dict()
e0 = 0
for e1 in rings:
norms = np.array([
[i, j, get_norm(verts[i] - verts[j])]
for i in range(e0, e1)
for j in it.chain(range(0, e0), range(e1, n))
])
if len(norms) == 0:
continue
i, j = norms[np.argmin(norms[:, 2])][:2].astype(int)
loop_connections[i] = j
loop_connections[j] = i
e0 = e1
# Setup bidirectional linked list
before = []
after = []
e0 = 0
for e1 in rings:
after += [*range(e0 + 1, e1), e0]
before += [e1 - 1, *range(e0, e1 - 1)]
e0 = e1
# Initialize edge triangles
edge_tris = []
i = 0
starting = True
while (i != 0 or starting):
starting = False
if i in loop_connections:
j = loop_connections[i]
edge_tris.append([before[i], i, j])
edge_tris.append([i, j, after[j]])
i = after[j]
else:
edge_tris.append([before[i], i, after[i]])
i = after[i]
# Set up a test for whether or not three indices
# form an ear of the polygon, meaning a convex corner
# which doesn't contain any other vertices
indices = list(range(n))
def is_ear(*tri_indices):
tri = [verts[i] for i in tri_indices]
v1 = tri[1] - tri[0]
v2 = tri[2] - tri[1]
cross = v1[0] * v2[1] - v2[0] * v1[1]
if orientation * cross < 0:
return False
for j in indices:
if j in tri_indices:
continue
elif is_inside_triangle(verts[j], *tri):
return False
return True
# Loop through and clip off all the ears
n_failures = 0
i = 0
while n_failures < len(edge_tris):
n = len(edge_tris)
edge_tri = edge_tris[i % n]
if is_ear(*edge_tri):
result.extend(edge_tri)
edge_tris[(i - 1) % n][2] = edge_tri[2]
edge_tris[(i + 1) % n][0] = edge_tri[0]
if edge_tri[1] in indices:
indices.remove(edge_tri[1])
edge_tris.remove(edge_tri)
n_failures = 0
else:
n_failures += 1
i += 1
return result