gltf-compare.py - mozsearch

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#!/usr/bin/env python3

# Copyright (C) 2026 The Qt Company Ltd.

# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0

"""Runs balsam twice on the same glTF asset, once through the Assimp

importer and once through the native glTF importer, and diffs the generated

QML, keyframe, and mesh output. A bring-up and review aid, not a CI gate.

Usage: gltf-compare.py <path/to/balsam> <asset.gltf> [balsam options...]

"""

import filecmp

import os

import subprocess

import sys

import tempfile

def run_balsam(balsam, asset, outdir, options, native):

    env = os.environ.copy()

    if native:

        env.pop("QT_QUICK3D_DISABLE_NATIVE_GLTF", None)

    else:

        env["QT_QUICK3D_DISABLE_NATIVE_GLTF"] = "1"

    subprocess.run([balsam, *options, "-o", outdir, asset], env=env, check=True,

                   capture_output=True)

def compare_trees(a, b):

    differences = []

    for root, _, files in os.walk(a):

        rel = os.path.relpath(root, a)

        for name in files:

            pa = os.path.join(root, name)

            pb = os.path.join(b, rel, name)

            if not os.path.exists(pb):

                differences.append(f"only in assimp output: {os.path.join(rel, name)}")

            elif not filecmp.cmp(pa, pb, shallow=False):

                differences.append(f"differs: {os.path.join(rel, name)}"

                                   f" ({os.path.getsize(pa)} vs {os.path.getsize(pb)} bytes)")

    for root, _, files in os.walk(b):

        rel = os.path.relpath(root, b)

        for name in files:

            if not os.path.exists(os.path.join(a, rel, name)):

                differences.append(f"only in native output: {os.path.join(rel, name)}")

    return differences

def main():

    if len(sys.argv) < 3:

        print(__doc__)

        return 2

    balsam, asset, options = sys.argv[1], sys.argv[2], sys.argv[3:]

    with tempfile.TemporaryDirectory() as tmp:

        out_assimp = os.path.join(tmp, "assimp")

        out_native = os.path.join(tmp, "native")

        os.makedirs(out_assimp)

        os.makedirs(out_native)

        run_balsam(balsam, asset, out_assimp, options, native=False)

        run_balsam(balsam, asset, out_native, options, native=True)

        differences = compare_trees(out_assimp, out_native)

        if not differences:

            print(f"{asset}: outputs are identical")

            return 0

        print(f"{asset}: {len(differences)} difference(s)")

        for diff in differences:

            print(f"  {diff}")

        return 1

if __name__ == "__main__":

    sys.exit(main())