TriSoupMesh.py

#!/usr/bin/env python2
# -*- coding: utf-8 -*-
"""
Created on Fri Nov  2 14:27:39 2018

@author: lukemcculloch
"""

import numpy as np

from Utilities import normalize, norm

# A "triangle soup" mesh, with an array of vertices and list of face indices
# Generally, this class exists only for interfacing with external components, such as IO and visualization.
# We encourage all mesh computation to be performed on a halfedge mesh.
class TriSoupMesh(object):

    ### Construct a new mesh froms a vert array and a tri list
    def __init__(self, verts, tris, 
                 faceAttr=dict(), vertAttr=dict()):
        
        # A Nx3 list of vertex positions
        self.verts = np.array(verts)
        self.tris = np.array(tris, dtype=np.uint32)

        # A Mx3 list of tuples, where each gives an (i,j,k) CCW triangular face
        self.nVerts = len(verts)
        self.nTris = len(tris)

        # Dictionaries to hold various data on the faces and vertices
        # (as indexed lists): vertAttr['value'] = [val1, val2, val3...]
        self.faceAttr = faceAttr
        self.vertAttr = vertAttr

        # Numpy-ify all the attr data
        # TODO really need some kind of more general solution here... this
        # will fail on lots of things
        for key in self.faceAttr:
            self.faceAttr[key] = np.array(self.faceAttr[key])
        for key in self.vertAttr:
            self.vertAttr[key] = np.array(self.vertAttr[key])


    # Compute face and vertex normals, 
    #  using numpy operations for efficiency
    # This will generally be much faster 
    #  than computing normals on the halfedge
    # mesh.
    # 'useExisting' will cause this method 
    #   to exit immediately if there is already
    #   a 'normal' attribute defined on the vertices
    def computeNormals(self, useExisting=True):

        if useExisting and 'normal' in self.vertAttr:
            #print("Skipping normal computation, normals are already defined")
            return

        # Not implemented. 
        #  Students SHOULD NOT touch this version of the function,
        #  they should implement it in HalfEdgeMesh.py. 
        # This alternate implementations
        #  exists for efficiency reasons 
        #  in certain IO scenarios.

        self.vertAttr['normal'] = np.zeros( self.verts.shape, dtype=self.verts.dtype)