HartOMat/render-worker/scripts/export_step_to_gltf.py

"""OCC-native STEP → GLB export script.

Reads a STEP file via OCP/XCAF (preserving part names and embedded colors),
tessellates with BRepMesh, optionally applies per-part hex colors, and writes
a binary GLB in meters (Y-up, glTF convention).

No Blender required. Uses the same OCP bindings that cadquery ships with.

Usage:
    python3 export_step_to_gltf.py \
        --step_path /path/to/file.stp \
        --output_path /path/to/output.glb \
        [--linear_deflection 0.1] \
        [--angular_deflection 0.5] \
        [--color_map '{"RingInner": "#4C9BE8", "RingOuter": "#E85B4C"}']

Exit 0 on success, exit 1 on failure.
"""
from __future__ import annotations

import argparse
import json
import sys
import traceback
from pathlib import Path

PALETTE_HEX = [
    "#4C9BE8", "#E85B4C", "#4CBE72", "#E8A84C", "#A04CE8",
    "#4CD4E8", "#E84CA8", "#7EC850", "#E86B30", "#5088C8",
]


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser()
    parser.add_argument("--step_path", required=True)
    parser.add_argument("--output_path", required=True)
    parser.add_argument(
        "--linear_deflection", type=float, default=0.1,
        help="OCC linear deflection for tessellation (mm). Smaller = finer mesh. Default 0.1",
    )
    parser.add_argument(
        "--angular_deflection", type=float, default=0.5,
        help="OCC angular deflection (radians). Default 0.5",
    )
    parser.add_argument(
        "--color_map", default="{}",
        help='JSON dict mapping part name → hex color, e.g. \'{"Ring": "#4C9BE8"}\'',
    )
    return parser.parse_args()


def _hex_to_occ_color(hex_color: str):
    """Convert '#RRGGBB' → Quantity_Color (linear float)."""
    from OCP.Quantity import Quantity_Color, Quantity_TOC_RGB
    h = hex_color.lstrip("#")
    if len(h) < 6:
        return Quantity_Color(0.7, 0.7, 0.7, Quantity_TOC_RGB)
    r = int(h[0:2], 16) / 255.0
    g = int(h[2:4], 16) / 255.0
    b = int(h[4:6], 16) / 255.0
    return Quantity_Color(r, g, b, Quantity_TOC_RGB)


def _apply_color_map(shape_tool, color_tool, free_labels, color_map: dict) -> None:
    """Apply hex colors from color_map to matching shapes by name (case-insensitive substring)."""
    from OCP.TDF import TDF_LabelSequence
    from OCP.TDataStd import TDataStd_Name
    from OCP.XCAFDoc import XCAFDoc_ShapeTool

    # XCAFDoc_ColorType: XCAFDoc_ColorGen=0, XCAFDoc_ColorSurf=1, XCAFDoc_ColorCurv=2
    try:
        from OCP.XCAFDoc import XCAFDoc_ColorSurf as COLOR_SURF
    except ImportError:
        COLOR_SURF = 1  # integer fallback

    def _visit(label) -> None:
        name_attr = TDataStd_Name()
        name = ""
        if label.FindAttribute(TDataStd_Name.GetID_s(), name_attr):
            name = name_attr.Get().ToExtString()

        if name:
            for part_name, hex_color in color_map.items():
                if part_name.lower() in name.lower() or name.lower() in part_name.lower():
                    color_tool.SetColor(label, _hex_to_occ_color(hex_color), COLOR_SURF)
                    break

        components = TDF_LabelSequence()
        XCAFDoc_ShapeTool.GetComponents_s(label, components)
        for i in range(1, components.Length() + 1):
            _visit(components.Value(i))

    for i in range(1, free_labels.Length() + 1):
        _visit(free_labels.Value(i))


def _apply_palette_colors(shape_tool, color_tool, free_labels) -> None:
    """Assign palette colors to leaf shapes when no color_map is provided."""
    from OCP.TDF import TDF_LabelSequence
    from OCP.XCAFDoc import XCAFDoc_ShapeTool

    try:
        from OCP.XCAFDoc import XCAFDoc_ColorSurf as COLOR_SURF
    except ImportError:
        COLOR_SURF = 1

    leaves: list = []

    def _collect(label) -> None:
        components = TDF_LabelSequence()
        XCAFDoc_ShapeTool.GetComponents_s(label, components)
        if components.Length() == 0:
            leaves.append(label)
        else:
            for i in range(1, components.Length() + 1):
                _collect(components.Value(i))

    for i in range(1, free_labels.Length() + 1):
        _collect(free_labels.Value(i))

    for idx, label in enumerate(leaves):
        occ_color = _hex_to_occ_color(PALETTE_HEX[idx % len(PALETTE_HEX)])
        color_tool.SetColor(label, occ_color, COLOR_SURF)


def main() -> None:
    args = parse_args()
    color_map: dict = json.loads(args.color_map)

    from OCP.STEPCAFControl import STEPCAFControl_Reader
    from OCP.TDocStd import TDocStd_Document
    from OCP.XCAFApp import XCAFApp_Application
    from OCP.XCAFDoc import XCAFDoc_DocumentTool
    from OCP.TCollection import TCollection_ExtendedString, TCollection_AsciiString
    from OCP.TDF import TDF_LabelSequence
    from OCP.BRepMesh import BRepMesh_IncrementalMesh
    from OCP.IFSelect import IFSelect_RetDone
    from OCP.Message import Message_ProgressRange

    # --- Init XDE document ---
    app = XCAFApp_Application.GetApplication_s()
    doc = TDocStd_Document(TCollection_ExtendedString("MDTV-CAF"))
    app.InitDocument(doc)

    # --- Read STEP into XDE (preserves part names + embedded colors) ---
    reader = STEPCAFControl_Reader()
    reader.SetNameMode(True)
    reader.SetColorMode(True)
    reader.SetLayerMode(True)
    status = reader.ReadFile(args.step_path)
    if status != IFSelect_RetDone:
        print(f"ERROR: STEPCAFControl_Reader failed (status={status})", file=sys.stderr)
        sys.exit(1)
    reader.Transfer(doc)

    shape_tool = XCAFDoc_DocumentTool.ShapeTool_s(doc.Main())
    color_tool = XCAFDoc_DocumentTool.ColorTool_s(doc.Main())

    # --- Tessellate all free shapes ---
    free_labels = TDF_LabelSequence()
    shape_tool.GetFreeShapes(free_labels)
    print(f"Found {free_labels.Length()} root shape(s), tessellating "
          f"(linear={args.linear_deflection}mm, angular={args.angular_deflection}rad) …")

    for i in range(1, free_labels.Length() + 1):
        shape = shape_tool.GetShape_s(free_labels.Value(i))
        if not shape.IsNull():
            BRepMesh_IncrementalMesh(
                shape,
                args.linear_deflection,
                False,   # isRelative
                args.angular_deflection,
                True,    # isInParallel
            )

    # --- Apply colors ---
    if color_map:
        _apply_color_map(shape_tool, color_tool, free_labels, color_map)
        print(f"Applied color_map ({len(color_map)} entries)")
    else:
        _apply_palette_colors(shape_tool, color_tool, free_labels)
        print("Applied palette colors (no color_map provided)")

    # --- Scale shapes mm → m before GLB export ---
    # RWMesh_CoordinateSystemConverter is not wrapped in OCP Python bindings.
    # Pre-scale each free shape by 0.001 (mm → m) using BRepBuilderAPI_Transform.
    from OCP.gp import gp_Trsf
    from OCP.BRepBuilderAPI import BRepBuilderAPI_Transform

    trsf = gp_Trsf()
    trsf.SetScaleFactor(0.001)

    for i in range(1, free_labels.Length() + 1):
        label = free_labels.Value(i)
        orig_shape = shape_tool.GetShape_s(label)
        if not orig_shape.IsNull():
            scaled = BRepBuilderAPI_Transform(orig_shape, trsf, True).Shape()
            shape_tool.SetShape(label, scaled)

    print("Shapes scaled mm → m")

    # --- Export GLB via RWGltf_CafWriter ---
    from OCP.RWGltf import RWGltf_CafWriter

    writer = RWGltf_CafWriter(TCollection_AsciiString(args.output_path), True)  # True = binary GLB
    # Z-up → Y-up rotation is applied by RWGltf_CafWriter by default (OCC 7.6+).

    # Perform export
    try:
        from OCP.TColStd import TColStd_IndexedDataMapOfStringString
        metadata = TColStd_IndexedDataMapOfStringString()
        ok = writer.Perform(doc, metadata, Message_ProgressRange())
    except TypeError:
        # Older API without metadata dict
        ok = writer.Perform(doc, Message_ProgressRange())

    out = Path(args.output_path)
    if not ok or not out.exists() or out.stat().st_size == 0:
        print(f"ERROR: RWGltf_CafWriter.Perform returned ok={ok}, file exists={out.exists()}",
              file=sys.stderr)
        sys.exit(1)

    print(f"GLB exported: {out.name} ({out.stat().st_size // 1024} KB)")


try:
    main()
except SystemExit:
    raise
except Exception:
    traceback.print_exc()
    sys.exit(1)