examples/export_mesh_with_superfit.py

#!/usr/bin/env python3
"""Example: export a reconstructed mesh from a released primitive assembly.

This example requires the SuperFit runtime:

    https://github.com/BardOfCodes/superfit

Run from the dataset repository root after installing SuperFit and its runtime
dependencies:

    python examples/export_mesh_with_superfit.py \
        --source toys4k \
        --method superfrustum \
        --object-id airplane_002 \
        --output airplane_002.obj

The mesh path follows SuperFit's own export flow: load the released stats dict,
recover the saved primitive expression, evaluate it on a 3D grid, then convert
the SDF to a mesh with SuperFit's ``sdf_to_mesh`` helper.
"""

from __future__ import annotations

import argparse
import pickle
import sys
from pathlib import Path
from typing import Any

# Allow `import load_release` when executed as `python examples/export_mesh_with_superfit.py`
_REPO_ROOT = Path(__file__).resolve().parent.parent
if str(_REPO_ROOT) not in sys.path:
    sys.path.insert(0, str(_REPO_ROOT))

from load_release import ReleaseIndex  # noqa: E402


def _import_superfit() -> tuple[Any, Any, Any, Any, Any]:
    try:
        from geolipi.torch_compute import Sketcher, recursive_evaluate
        from superfit.symbolic.utils import fetch_singular_expr_eval
        from superfit.utils.io import get_best_expr
        from superfit.utils.mesh_sdf import sdf_to_mesh
    except ImportError as exc:
        raise SystemExit(
            "This example requires SuperFit and its runtime dependencies. "
            "Install or add SuperFit to PYTHONPATH; see "
            "https://github.com/BardOfCodes/superfit"
        ) from exc
    return Sketcher, recursive_evaluate, fetch_singular_expr_eval, get_best_expr, sdf_to_mesh


def load_expression(
    assembly_path: Path,
    *,
    program: str,
    iter_idx: int | None,
    temperature: float,
    device: str,
) -> Any:
    _, _, fetch_singular_expr_eval, get_best_expr, _ = _import_superfit()
    with assembly_path.open("rb") as fh:
        info = pickle.load(fh)

    expr = get_best_expr(info, iter_idx=iter_idx, prog_type=program)
    return fetch_singular_expr_eval(
        expr.tensor(device=device),
        temperature=temperature,
        relaxed_eval=True,
        remove_marker=True,
        device=device,
    )


def export_mesh(expr: Any, output_path: Path, *, resolution: int, device: str) -> None:
    Sketcher, recursive_evaluate, _, _, sdf_to_mesh = _import_superfit()
    sketcher = Sketcher(resolution=resolution, n_dims=3, device=device)
    sdf = recursive_evaluate(expr.tensor(device=device), sketcher)
    mesh = sdf_to_mesh(sdf, sketcher)
    output_path.parent.mkdir(parents=True, exist_ok=True)
    mesh.export(output_path)


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--root", type=Path, default=_REPO_ROOT, help="Dataset repo root.")
    parser.add_argument("--source", default="toys4k", choices=["toys4k", "partobjaverse"])
    parser.add_argument("--method", default="superfrustum")
    parser.add_argument("--object-id", required=True, help="Instance id to export.")
    parser.add_argument(
        "--program",
        default="pruned_program",
        help="Saved program key to export, e.g. pruned_program or best_program.",
    )
    parser.add_argument(
        "--iter-idx",
        type=int,
        default=None,
        help="Optimization iteration to read. Default: final iteration recorded in the artifact.",
    )
    parser.add_argument("--resolution", type=int, default=128, help="SDF grid resolution.")
    parser.add_argument(
        "--temperature",
        type=float,
        default=10000.0,
        help="Temperature used when resolving stochastic primitive expressions.",
    )
    parser.add_argument(
        "--device",
        default="cuda",
        help="Torch device for expression evaluation. SuperFit mesh export typically requires CUDA.",
    )
    parser.add_argument("--output", type=Path, required=True, help="Output mesh path, e.g. out.obj.")
    args = parser.parse_args()

    index = ReleaseIndex(args.root)
    row = index.get(args.source, args.method, args.object_id)
    assembly_path = index.artifact_path(row, "primitive_assembly")

    expr = load_expression(
        assembly_path,
        program=args.program,
        iter_idx=args.iter_idx,
        temperature=args.temperature,
        device=args.device,
    )
    export_mesh(expr, args.output, resolution=args.resolution, device=args.device)
    print(f"Exported {args.output}")


if __name__ == "__main__":
    main()