Class _EdgeCollapser

python/pymesh/meshutils/collapse_short_edges.py:10–109

Wrapper class for C++ ShortEdgeRemoval class. Attributes: input_mesh: The input mesh. vertices (2D array): the output vertices. faces (2D array): the output faces. Examples: A common usage:: collapser = _EdgeCollapser.create(mesh) c

from PyMesh import ShortEdgeRemoval, IsolatedVertexRemoval, FinFaceRemoval

class _EdgeCollapser(object):
    """ Wrapper class for C++ ShortEdgeRemoval class.

    Attributes:
        input_mesh: The input mesh.
        vertices (2D array): the output vertices.
        faces (2D array): the output faces.

    Examples:
        A common usage::

            collapser = _EdgeCollapser.create(mesh)
            collapser.keep_features()
            collapser.collapse(0.1, None)
            print(collapser.vertices)
            print(collapser.faces)
    """
    @classmethod
    def create(cls, mesh):
        return _EdgeCollapser(mesh)

    @classmethod
    def create_raw(cls, vertices, faces):
        mesh = form_mesh(vertices, faces)
        return _EdgeCollapser(mesh)

    def __init__(self, mesh):
        self.input_mesh = mesh
        if self.input_mesh.vertex_per_face != 3:
            raise RuntimeError("Only triangle mesh is supported!  "
                    "Input has {} vertices per face".format(
                        self.input_mesh.vertex_per_face))
        self.logger = logging.getLogger(__name__)
        self.importance = None

    @timethis
    def keep_features(self):
        """ Preserve sharp edges and boundaries.
        """
        if not self.input_mesh.has_attribute("vertex_dihedral_angle"):
            self.input_mesh.add_attribute("vertex_dihedral_angle")
        dihedral_angle = self.input_mesh.get_attribute("vertex_dihedral_angle")
        self.importance = np.round(dihedral_angle * 4 / math.pi).astype(int)

        # keep boundary.
        bd_vertices = self.input_mesh.boundary_vertices
        self.importance[bd_vertices] = 10

    @timethis
    def collapse(self, abs_threshold, rel_threshold):
        """ Note this method remove all edges with length less than threshold.
        This could result in a non-manifold mesh.
        """
        min_edge_length = abs_threshold
        if rel_threshold is not None:
            ave_edge_len = self.__get_ave_edge_length()
            min_edge_length = rel_threshold  * ave_edge_len
        self.logger.info("Minimum edge threshold: {:.3}".format(min_edge_length))