Aggregate vertex data with pycollada

aggregate_mesh.py

import collada
import sys
import os.path
from itertools import chain
import numpy

def uniqify_multidim_indexes(sourcedata, indices, return_map=False):
    """Just like numpy.unique except that it works with multi-dimensional arrays.
    Given a source array and indexes into the source array, will keep only unique
    indices into the source array, rewriting the indices to point to the new
    compressed source array""" 
    unique_data, index_map = numpy.unique(sourcedata.view([('',sourcedata.dtype)]*sourcedata.shape[1]), return_inverse=True)
    index_map = numpy.cast['int32'](index_map)
    if return_map:
        return unique_data.view(sourcedata.dtype).reshape(-1,sourcedata.shape[1]), index_map[indices], index_map
    return unique_data.view(sourcedata.dtype).reshape(-1,sourcedata.shape[1]), index_map[indices]

def aggregate_dae(mesh):
    all_vertices = []
    all_vert_indices = []
    vertex_offset = 0
    num_prims = 0

    for boundgeom in chain(mesh.scene.objects('geometry'), mesh.scene.objects('controller')):
        if isinstance(boundgeom, collada.controller.BoundController):
            boundgeom = boundgeom.geometry

        for boundprim in boundgeom.primitives():
            if boundprim.vertex_index is None or len(boundprim.vertex_index) == 0:
                continue
            if not isinstance(boundprim, collada.triangleset.BoundTriangleSet):
                continue

            print 'Adding primitive', boundprim
            all_vertices.append(boundprim.vertex)
            all_vert_indices.append(boundprim.vertex_index + vertex_offset)
            vertex_offset += len(boundprim.vertex)
            num_prims += 1

    all_vertices = numpy.concatenate(all_vertices)
    all_vert_indices = numpy.concatenate(all_vert_indices)
    
    print
    print 'Concatenated source data is shape', all_vertices.shape
    print 'Concatenated indices is shape', all_vert_indices.shape
    
    all_vertices, all_vert_indices = uniqify_multidim_indexes(all_vertices, all_vert_indices)

    print
    print 'After compression...'
    print 'Concatenated source data is shape', all_vertices.shape
    print 'Concatenated indices is shape', all_vert_indices.shape

if __name__ == '__main__':
    if len(sys.argv) != 2:
        print >> sys.stderr, 'Usage: python aggregate_mesh.py file.dae'
        sys.exit(1)
    aggregate_dae(collada.Collada(sys.argv[1]))

# $ python ~/test/aggregate_mesh.py TwinBridge.dae 
# Adding primitive <BoundTriangleSet length=310>
# Adding primitive <BoundTriangleSet length=376>
# Adding primitive <BoundTriangleSet length=33>
# Adding primitive <BoundTriangleSet length=77>
# Adding primitive <BoundTriangleSet length=13>
# Adding primitive <BoundTriangleSet length=15>
# Adding primitive <BoundTriangleSet length=4>
# Adding primitive <BoundTriangleSet length=2>
#
# Concatenated source data is shape (1630, 3)
# Concatenated indices is shape (830, 3)
#
# After compression...
# Concatenated source data is shape (415, 3)
# Concatenated indices is shape (830, 3)