mesh.Mesh.cut_with_plane#

Mesh.cut_with_plane(p, n, side='+', closed=False)#

Cut a triangular Mesh with a plane.

This operation splits a mesh by a plane defined by a point and a normal vector. It returns the portion of the mesh lying on the selected side of the plane. Unlike clip_with_plane(), this function modifies elements that intersect with the plane by slicing them, possibly generating new triangles along the cut.

Parameters#

parray_like of shape (3,)

A point lying on the cutting plane.

narray_like of shape (3,)

The normal vector defining the cutting plane.

side: ‘+’ | ‘-’

Default (‘+’) is to return the elements at the positive side of the plane, as defined by the normal vector.

closedbool

Whether to fill (cap) the open section created by cutting the mesh. If True, a new set of triangles is generated along the cutting plane to close the opening, preserving watertightness if the original mesh was closed.

Returns#

Mesh

A new mesh corresponding to the portion of the original mesh lying on the selected side of the cutting plane.

Notes#

This method is only implemented for meshes with eltype='tri3'.

See Also#

  • clip_with_plane(): Similar operation, but only keeps complete elements on one side of the plane without modifying or generating new ones.

Examples#

>>> cube = Mesh(eltype='hex8').border_mesh().convert('tri3')
>>> half = cube.cut_with_plane([0.5, 0.0, 0.0], [1.0, 0.0, 0.0])
>>> print(half)
Mesh: n_nodes: 12, n_elems: 14, plexitude: 3, level: 2, eltype: tri3
  BBox: [0.5 0.  0. ], [1. 1. 1.]
  Size: [0.5 1.  1. ]
  Length: 4.0  Area: 3.0

>>> half_closed = cube.cut_with_plane([0.5, 0.0, 0.0],
...                                   [1.0, 0.0, 0.0],
...                                   side='-',
...                                   closed=True)
>>> print(half_closed)
Mesh: n_nodes: 12, n_elems: 20, plexitude: 3, level: 2, eltype: tri3
  BBox: [0. 0. 0.], [0.5 1.  1. ]
  Size: [0.5 1.  1. ]
  Length: 0.0  Area: 4.0
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