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MeshTrimmer Class

The MeshTrimmer class provides functionalities for manipulating 3D meshes (typically in STL format) and trimming lattice structures using these meshes. It can be used to load, save, scale, move, and perform geometric checks on meshes. Additionally, it allows for cutting lattice beams that intersect with a mesh surface.

📦 Features

  • Load and save .stl mesh files
  • Automatically reposition mesh to origin
  • Check whether a point or a lattice cell is inside the mesh
  • Trim beams that intersect the mesh surface
  • Use with a lattice generation process for geometrically conforming trimming

🧰 Dependencies

🧱 Class Usage

from src.pyLatticeDesign.plotting_lattice import LatticePlotting
from src.pyLatticeDesign.lattice import Lattice

from data.inputs.mesh_file.mesh_trimmer import MeshTrimmer

name_mesh = "CutedBone"  # get from https://anatomytool.org/content/thunthu-3d-model-bones-lower-limb
mesh_trimmer = MeshTrimmer(name_mesh)
mesh_trimmer.plot_mesh(zoom = 3)

name_lattice = "design/BCC_trimmed_example"
lattice_object = Lattice(name_lattice, mesh_trimmer)
lattice_object.cut_beam_with_mesh_trimmer()

vizualizer = LatticePlotting()
vizualizer.visualize_lattice(lattice_object, beam_color_type="radii")

🧩 Methods

__init__(mesh_name: str = None)

Initializes a MeshTrimmer object. Optionally loads a mesh at initialization.

load_mesh(mesh_name: str)

Loads a mesh from the Mesh/ directory (STL format). Automatically handles extension and path formatting.

save_mesh(output_name: str)

Saves the current mesh to the Mesh/ directory, with automatic .stl extension handling.

scale_mesh(scale: float)

Scales the mesh uniformly and moves its minimum corner to the origin.

move_mesh_to_origin()

Translates the mesh so that its minimum bounding box corner is at the origin.

is_inside_mesh(point: array-like) -> bool

Checks if a given 3D point is located inside the mesh volume.

is_cell_in_mesh(cell: Cell) -> bool

Returns True if at least one corner of the given Cell object is inside the mesh. Used to filter cells during lattice generation.

cut_beams_at_mesh_intersection(cells: list[Cell])

Cuts or removes beams in the provided Cell list depending on their intersection with the mesh surface.

  • Fully outside: removed
  • Partially intersecting: shortened
  • Inside: unchanged

find_intersection_with_mesh(beam: Beam) -> tuple[float, float, float] | None

Uses pyembree acceleration to find the first intersection between a beam and the mesh surface. Returns intersection point or None if no hit.

plot_mesh()

Visualizes the current mesh using matplotlib in a 3D view.

  • The mesh is displayed with translucent cyan faces and black edges.
  • The camera is centered around the mesh centroid, with equal zoom in all directions.
  • The 3D axes and background are hidden for a cleaner visualization.

📁 File Structure Convention

  • Mesh files are expected to be stored under a data/inputs/mesh_file/ folder.
  • STL format is enforced.

🛠️ Limitations

  • Only beams that haven’t already been modified (beam_mod == False) can be trimmed, due to the lack of implementation for simulating trimmed lattice structures.