Mesh Subdivision
Due to the connectivity data attached to the meshes data structures, subdividing meshes by hand is unsafe and can lead to faulty results. To correctly apply subdivisions, one needs to first convert back the mesh to a RawMeshData, apply the combinatorial functions, and rebuild a correct mesh. This is handled by the SurfaceSubdivision and the VolumeSubdivision classes, which are designed to be used in a with block:
import mouette as M
surface = M.mesh.load("/path/to/my/mesh.obj")
# At the start of the with block, the mesh is transformed into a RawMeshData and its connectivity is disabled
with M.mesh.SurfaceSubdivision(surface) as editor:
# Call here the subdivision functions
editor.subdivide_triangles_3quads()
editor.triangulate()
# When exiting the 'with' block, the mesh is transformed back into a SurfaceMesh
# and its connectivity is regenerated
M.mesh.save(surface, "path/to/my/new/mesh.obj")
SurfaceSubdivision(mesh, verbose=False)
Bases: Logger
loop_subdivision(n=1)
Subdivides triangles of a mesh in 4 triangles by splitting along middle of edges. If the mesh is not triangulated, will triangulate the mesh first.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
n
|
int
|
Number of times the subdivision is applied. Defaults to 1. |
1
|
split_face_as_fan(face_id)
Adds a vertex at the barycenter of face 'face_id' and create a fan of triangles that replaces the face
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
face_id
|
int
|
the face to split |
required |
subdivide_triangles_3quads()
Subdivides triangles of a mesh in 3 quads by adding a point at the barycenter and three middles of edges. If the mesh is not triangulated, will triangulate the mesh first.
subdivide_triangles_6(repeat=1)
Subdivides triangles of a mesh in 6 triangles by adding a point at the barycenter and three middles of edges. If the mesh is not triangulated, will triangulate the mesh first.
Same operation as subdividing into 3 quads and then splitting the quads along the corner-barycenter diagonal.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
repeat
|
int
|
number of successive subdivisions. Eventual first triangulation does not count. Defaults to 1. |
1
|
triangulate()
Triangulates all faces of a mesh. Calls triangulate_face on every faces.
triangulate_face(face_id)
Triangulates the face "face_id"
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
face_id
|
int
|
the face to triangulate |
required |
VolumeSubdivision(mesh, verbose=False)
Bases: Logger
split_cell_as_fan(cell_id)
Adds a vertex at the barycenter of cell 'cell_id' and create a fan of tetrahedra that replaces the cell. If the cell 'cell_id' is not a tetrahedron, does nothing.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
mesh
|
VolumeMesh
|
the input mesh |
required |
cell_id
|
int
|
the (tetrahedral) cell to split |
required |
Returns:
| Type | Description |
|---|---|
VolumeMesh
|
the modified input mesh |
split_tet_from_face_center(face_id)
Split the triangle face_id into three triangles by adding a point at its barycenter,
and split adjacent tetrahedra accordingly.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
face_id
|
int
|
index of the face to split |
required |
split_edge(polyline, edge_ind)
Split an edge of a polyline in half by adding a new vertex
Note
Polylines do not need a specific subdivision class to be used in a with block since their connectivity is simpler.
Connectivity is cleared after processing.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
mesh
|
PolyLine
|
the input polyline |
required |
edge_ind
|
int
|
index of the edge to split |
required |
Returns:
| Name | Type | Description |
|---|---|---|
PolyLine |
PolyLine
|
the processed Polyline |
split_double_boundary_edges_triangles(mesh)
A triangle with double edge on the boundary can occur on the border in a case like :
This function detects every occurrences of such a configuration and split the problematic triangle in three by adding a new vertex in the middle. Uses the SurfaceSubdivision class.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
mesh
|
Mesh
|
the mesh (modified in place) |
required |
Raises:
| Type | Description |
|---|---|
Exception
|
Isolated vertex |
Returns:
| Name | Type | Description |
|---|---|---|
SurfaceMesh |
SurfaceMesh
|
the modified input mesh |