Outie

Turns every face of a mesh to point out, like an outie, even when the mesh is not closed.

A Python port of libigl's reorient_facets_raycast, the reference code for Takayama, Jacobson, Kavan and Sorkine-Hornung, A Simple Method for Correcting Facet Orientations in Polygon Meshes Based on Ray Casting, 2014.

How

Faces that share edges are gathered into patches first, so a patch is decided as one. Rays are traced by Embree, through trimesh.

Use

import outie

polygons = outie.orient(polygons)              # a list of rings, each n by 3
faces = outie.orient_mesh(vertices, faces)     # triangles: vertices n by 3, faces m by 3

Both return what they were given, with the faces that pointed in turned round. Underneath are libigl's own two functions, with its names, arguments and outputs, for callers who need to know which faces moved or which patch each belongs to:

flip, patch = outie.reorient_facets_raycast(vertices, faces)   # per triangle: turn it? and its patch
faces, patch = outie.bfs_orient(faces)                         # faces wound to agree, and their patches

The paper's settings are keyword arguments with libigl's defaults: rays_total, rays_minimum, facet_wise, use_parity, and seed so a run repeats.

Licence

MPL-2.0, as libigl is: this is a port of its code, taken at libigl commit 7100764. The method is its authors'.