src/3mf2mmuv3.py

#!/bin/env python3
"""
Convert a standard 3mf generated by OpenSCAD with color information
to a MMU‑painted 3mf that PrusaSlicer expects
"""

import argparse
import logging
import zipfile
from pathlib import Path
from xml.etree import ElementTree as ET

# Mapping from extruder index to paint color code used by PrusaSlicer / BambuStudio
PAINT_COLOR_MAP = [
    None,
    "8",
    "0C",
    "1C",
    "2C",
    "3C",
    "4C",
    "5C",
    "6C",
    "7C",
    "8C",
    "9C",
    "AC",
    "BC",
    "CC",
    "DC",
]


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--loglevel",
        type=str,
        choices=["INFO", "DEBUG", "WARN", "ERROR"],
        default="INFO",
        help="Logging Level",
    )
    parser.add_argument(
        "--force",
        default=False,
        action="store_true",
        help="Force overwriting the output file",
    )
    parser.add_argument("openscad_3mf", help="OpenSCAD 3MF input")
    parser.add_argument("prusaslicer_3mf", help="PrusaSlicer 3MF output")
    args = parser.parse_args()

    logging.basicConfig(
        format="%(asctime)s %(levelname)8s %(message)s", level=args.loglevel
    )

    # register the namespaces we care about
    namespaces = {
        "xml": "http://www.w3.org/XML/1998/namespace",
        "": "http://schemas.microsoft.com/3dmanufacturing/core/2015/02",
        "p": "http://schemas.microsoft.com/3dmanufacturing/production/2015/06",
        "slic3rpe": "http://schemas.slic3r.org/3mf/2017/06",
    }
    for k, v in namespaces.items():
        ET.register_namespace(k, v)

    os3mf = Path(args.openscad_3mf)
    ps3mf = Path(args.prusaslicer_3mf)

    if not os3mf.exists():
        logging.error(f"The input file {os3mf} doesn't exist")
        exit(1)

    if ps3mf.exists() and not args.force:
        logging.error(
            f"The output file {ps3mf} exists and will not be overwritten without --force"
        )
        exit(1)

    with zipfile.ZipFile(
        ps3mf, "w", compression=zipfile.ZIP_DEFLATED, compresslevel=9
    ) as pszip:
        with zipfile.ZipFile(os3mf, "r") as oszip:
            # copy the files from the openscad 3mf to the prusaslicer 3mf
            for file in [
                x for x in oszip.infolist() if x.filename != "3D/3dmodel.model"
            ]:
                logging.info(f"Copying file {file}")
                pszip.writestr(file, oszip.open(file).read())

            model_raw = oszip.read("3D/3dmodel.model")

            logging.info("Updating 3dmodel.model")
            # Parse the XML
            model_root = ET.fromstring(str(model_raw, encoding="utf-8"))

            # Remove any existing Application metadata and set to PrusaSlicer
            for meta in list(model_root.findall("metadata")):
                if meta.get("name") == "Application":
                    model_root.remove(meta)
            # Add Application metadata
            app_meta = ET.Element(
                "metadata", {"name": "Application", "preserve": "1"}
            )
            app_meta.text = "PrusaSlicer"
            model_root.append(app_meta)

            # add slic3rpe metadata
            for k, v in {
                "slic3rpe:Version3mf": "1",
                "slic3rpe:MmPaintingVersion": "1",
                "BambuStudio:3mfVersion": "1",
            }.items():
                e = ET.Element("metadata", {"name": k})
                e.text = v
                model_root.append(e)

            # Set color attributes on triangles
            for t in model_root.findall(
                "resources/object/mesh/triangles/triangle", namespaces
            ):
                p1_value = t.get("p1")
                if not p1_value or p1_value == "0":
                    continue
                try:
                    p1_index = int(p1_value)
                except ValueError:
                    logging.warning(
                        f"Triangle has non‑integer p1 value: {p1_value}"
                    )
                    continue
                if p1_index < len(PAINT_COLOR_MAP):
                    color_code = PAINT_COLOR_MAP[p1_index]
                else:
                    logging.warning(
                        f"Material number {p1_index} is greater than supported extruders"
                    )
                    color_code = None
                if color_code:
                    t.set("slic3rpe:mmu_segmentation", color_code)
                    t.set("paint_color", color_code)

            model_text = str(
                ET.tostring(
                    model_root, encoding="utf-8", xml_declaration=True
                ),
                encoding="utf-8",
            )
            pszip.writestr("3D/3dmodel.model", model_text)


if __name__ == "__main__":
    main()