TetraMesh

C++: phynexis::utils::mesh::TetraMesh Python: phynexis.utils.TetraMesh Header: src/utils/mesh/tetra_mesh.hpp

Tetrahedral volume mesh: stores vertices and tetrahedra, with lazily computed boundary-derived data (surface facets, edges, nodes, and facet areas).

Constructors

TetraMesh()

Creates an empty tetrahedral mesh.

TetraMesh(other)

Copy constructor.

TetraMesh(vertices, tetrahedra)

Create from vertex and tetrahedron arrays.

Parameters:

Parameter	Type	Description
vertices	list[Vec3d]	Vertex positions
tetrahedra	list[Vec4i]	Tetrahedron vertex indices (4 per cell)

TetraMesh(surface, mesh_size)

Generate tetrahedral mesh from a triangle surface mesh.

Parameters:

Parameter	Type	Description
surface	TriangleMesh	Surface mesh to tetrahedralize
mesh_size	float	Target cell size

TetraMesh(stl_model, mesh_size)

Generate tetrahedral mesh from an STL model.

Parameters:

Parameter	Type	Description
stl_model	STLModel	STL model to tetrahedralize
mesh_size	float	Target cell size

TetraMesh(vertices, facets, mesh_size)

Generate tetrahedral mesh from raw vertices and surface facets.

Parameters:

Parameter	Type	Description
vertices	list[Vec3d]	Vertex positions
facets	list[Vec3i]	Surface triangle indices
mesh_size	float	Target cell size

Properties

Property	Type	Description
vertices	list[Vec3d]	Vertex positions (read/write)
tetrahedra	list[Vec4i]	Tetrahedron vertex indices (read/write)
surface_facets	list[Vec3i]	Surface triangle facets (lazy-computed)
surface_nodes	list[Vec3d]	Surface vertex positions (lazy-computed)
bound_facets	list[Vec3i]	Boundary facets (lazy-computed)
bound_edges	list[Vec2i]	Boundary edges (lazy-computed)
bound_nodes	list[int]	Boundary node indices (lazy-computed)
bound_facet_areas	list[float]	Area of each boundary facet (lazy-computed)
surface_node_linked_boundaries	list[list[int]]	Boundary groups linked to each surface node (lazy-computed)

Methods

sync_boundary()

Recompute all lazily-cached boundary data (surface facets, edges, nodes, areas). Called automatically when boundary properties are first accessed after a change.

invalidate_boundary_data()

Mark boundary cache as stale. The next access to boundary properties will trigger a recomputation.

get_surface_stl()

Returns: STLModel — surface mesh extracted from the tetrahedral boundary.

save_to(path, file, opt=SaveOptions())

Save mesh to file.

Parameters:

Parameter	Type	Default	Description
path	str	—	Directory path
file	str	—	File name
opt	SaveOptions	SaveOptions()	Save options

Example: Tetrahedralize an STL model

TetGen internally prints timing and statistics to stdout; actual vertex/tetrahedra counts may vary slightly across runs due to floating-point ordering.

import phynexis

# Create an STL sphere model
sphere = phynexis.utils.shape.Sphere(2.0)
stl = sphere.get_stl_model(100)

# Generate tetrahedral mesh with target cell size 0.5
tet = phynexis.utils.TetraMesh(stl, 0.5)

print("vertices:", len(tet.vertices))
print("tetrahedra:", len(tet.tetrahedra))
print("surface facets:", len(tet.surface_facets))
print("surface nodes:", len(tet.surface_nodes))

# Extract surface as STL
surface = tet.get_surface_stl()
print("surface stl vertices:", len(surface.vertices))
print("surface stl facets:", len(surface.facets))

# Save to VTK
opts = phynexis.utils.SaveOptions()
opts.overwrite = True
tet.save_to("/tmp/", "tetra_demo.vtk", opts)

Example: Create from vertices and tetrahedra

import phynexis

# Simple single-tetrahedron mesh
tet = phynexis.utils.TetraMesh()
tet.vertices = [
    phynexis.utils.Vec3d(0.0, 0.0, 0.0),
    phynexis.utils.Vec3d(1.0, 0.0, 0.0),
    phynexis.utils.Vec3d(0.0, 1.0, 0.0),
    phynexis.utils.Vec3d(0.0, 0.0, 1.0),
]
tet.tetrahedra = [phynexis.utils.Vec4i(0, 1, 2, 3)]

print("vertices:", len(tet.vertices))
print("tetrahedra:", len(tet.tetrahedra))

Output:

vertices: 4
tetrahedra: 1