Iterators and Circulators¶

This section demonstrates how to use mesh iterators and circulators. The example outputs on this page are based on the mesh from the previous section, which looks like this:

#  0 ==== 2
#  |\  0 /|
#  | \  / |
#  |2  1 3|
#  | /  \ |
#  |/  1 \|
#  3 ==== 4

Iterators¶

Iterators make it possible to enumerate the items of a mesh. For example, the code below iterates over all vertices of a mesh:

for vh in mesh.vertices():
    print(vh.idx())

Using the mesh from the previous section, this will produce the following output:

Note

Iterators and circulators return handles to mesh items instead of the items themself. For example, the vertex iterator returns vertex handles instead of actual vertices/points. You can access the vertex coordinates by calling point() with the appropriate vertex handle.

We can also iterate over all halfedges, edges and faces by calling halfedges(), edges() and faces() respectively:

# iterate over all halfedges
for heh in mesh.halfedges():
    print(heh.idx())

# iterate over all edges
for eh in mesh.edges():
    print(eh.idx())

# iterate over all faces
for fh in mesh.faces():
    print(fh.idx())

Circulators¶

Circulators provide the means to iterate over items adjacent to another item. For example, to iterate over the 1-ring of a vertex we can call vv(), which is short for vertex-vertex circulator, and pass the handle of the center vertex:

for vh in mesh.vv(vh1):
    print(vh.idx())

Using the mesh from the previous section, this will produce the following output:

We can also iterate over the adjacent halfedges, edges and faces of a vertex:

# iterate over all incoming halfedges
for heh in mesh.vih(vh1):
    print(heh.idx())

# iterate over all outgoing halfedges
for heh in mesh.voh(vh1):
    print(heh.idx())

# iterate over all adjacent edges
for eh in mesh.ve(vh1):
    print(eh.idx())

# iterate over all adjacent faces
for fh in mesh.vf(vh1):
    print(fh.idx())

To iterate over the items adjacent to a face we can use the following functions:

# iterate over the face's vertices
for vh in mesh.fv(fh0):
    print(vh.idx())

# iterate over the face's halfedges
for heh in mesh.fh(fh0):
    print(heh.idx())

# iterate over the face's edges
for eh in mesh.fe(fh0):
    print(eh.idx())

# iterate over all edge-neighboring faces
for fh in mesh.ff(fh0):
    print(fh.idx())