filter out nodes and textures from glTF

filter.py

#!/usr/bin/env python3

import json
import re
import sys

infile = 'Bistro_Exterior.gltf'
outfile = 'out.gltf'
name_pattern = 'BISTRO_RESEARCH_EXTERIOR_PARIS_BUILDING.*|BISTRO_RESEARCH_EXTERIOR_PARIS_STREET_.*'

name_matcher = re.compile(name_pattern)

if len(sys.argv) > 1:
    infile = sys.argv[1]

textures = set()
def add_textures(material):
    mr = material['pbrMetallicRoughness']
    for key in mr:
        if key.endswith('Texture'):
            textures.add(mr[key]['index'])
    for key in material:
        if key.endswith('Texture'):
            textures.add(material[key]['index'])

src = json.load(open(infile))
dst = {}
for key in src.keys():
    if key == 'nodes':
        nodes = dst[key] = src[key]
        src_indices = nodes[0]['children']
        dst_indices = []
        for index in src_indices:
            node = nodes[index]
            name = node['name'].upper()
            if name_matcher.match(name):
                dst_indices.append(index)
                mesh = src['meshes'][node['mesh']]
                for prim in mesh['primitives']:
                    material = src['materials'][prim['material']]
                    add_textures(material)
        nodes[0]['children'] = dst_indices
    else:
        dst[key] = src[key]

dst_textures = dst['textures'] = []
src_textures = src['textures']
for index in range(len(src_textures)):
    if index in textures:
        dst_textures.append(src_textures[index])
    else:
        dst_textures.append({})

json.dump(dst, open(outfile, 'w'), indent=2)