def _toTriMesh(self, mesh_data: MeshData) -> trimesh.base.Trimesh:
indices = mesh_data.getIndices()
if indices is None:
# some file formats (eg 3mf) don't supply indices, but have unique vertices per face
indices = numpy.arange(mesh_data.getVertexCount()).reshape(-1, 3)
return trimesh.base.Trimesh(vertices=mesh_data.getVertices(),
faces=indices,
vertex_normals=mesh_data.getNormals())
