python-occで色付きSTEPを出力する方法 / Exporting STEP with colors using python-occ

結果

結果

最小構成 / Minimum Example

from random import random

from OCC.Core.TDocStd import TDocStd_Document
from OCC.Core.XCAFApp import XCAFApp_Application
from OCC.Core.XCAFDoc import (
    XCAFDoc_DocumentTool_ShapeTool,
    XCAFDoc_DocumentTool_ColorTool,
    XCAFDoc_ColorGen,
)
from OCC.Core.TCollection import TCollection_ExtendedString
from OCC.Extend.TopologyUtils import TopologyExplorer
from OCC.Core.BRepPrimAPI import BRepPrimAPI_MakeBox
from OCC.Core.Quantity import Quantity_Color, Quantity_TOC_RGB
from OCC.Core.STEPCAFControl import STEPCAFControl_Writer

# https://techoverflow.net/2019/06/14/how-to-export-colored-step-files-in-opencascade/


def test():
    app = XCAFApp_Application.GetApplication()
    doc = TDocStd_Document(TCollection_ExtendedString(""))
    app.NewDocument(TCollection_ExtendedString("MDTV-XCAF"), doc)

    shape_tool = XCAFDoc_DocumentTool_ShapeTool(doc.Main())
    color_tool = XCAFDoc_DocumentTool_ColorTool(doc.Main())

    # Create a box
    box = BRepPrimAPI_MakeBox(10, 20, 30).Shape()
    for face in TopologyExplorer(box).faces():
        label = shape_tool.AddShape(face)
        color = Quantity_Color(random(), random(), random(), Quantity_TOC_RGB)
        color_tool.SetColor(label, color, XCAFDoc_ColorGen)

    # Export to STEP
    step_writer = STEPCAFControl_Writer()
    step_writer.SetColorMode(True)
    step_writer.Perform(doc, "hogehoge.stp")


if __name__ == "__main__":
    test()

クラス化 / Utility Class

from OCC.Core.TDocStd import TDocStd_Document
from OCC.Core.XCAFApp import XCAFApp_Application
from OCC.Core.XCAFDoc import (
    XCAFDoc_DocumentTool_ShapeTool,
    XCAFDoc_DocumentTool_ColorTool,
    XCAFDoc_ColorGen,
)
from OCC.Core.TCollection import TCollection_ExtendedString
from OCC.Extend.TopologyUtils import TopologyExplorer
from OCC.Core.BRepPrimAPI import BRepPrimAPI_MakeBox
from OCC.Core.Quantity import Quantity_Color, Quantity_TOC_RGB
from OCC.Core.STEPCAFControl import STEPCAFControl_Writer


class ColoredStepExport:
    def __init__(self):
        app = XCAFApp_Application.GetApplication()
        self.doc = TDocStd_Document(TCollection_ExtendedString(""))
        app.NewDocument(TCollection_ExtendedString("MDTV-XCAF"), self.doc)

        self.shape_tool = XCAFDoc_DocumentTool_ShapeTool(self.doc.Main())
        self.color_tool = XCAFDoc_DocumentTool_ColorTool(self.doc.Main())

    def add_shape(self, shape, color=None):
        label = self.shape_tool.AddShape(shape)
        if color:
            if isinstance(color, Quantity_Color):
                self.color_tool.SetColor(label, color, XCAFDoc_ColorGen)
            elif isinstance(color, (list, tuple)) and len(color) == 3:
                color = Quantity_Color(*[c / 255 for c in color], Quantity_TOC_RGB)
                self.color_tool.SetColor(label, color, XCAFDoc_ColorGen)
            else:
                raise ValueError("Invalid color format")

    def export(self, filename):
        step_writer = STEPCAFControl_Writer()
        step_writer.SetColorMode(True)
        step_writer.Perform(self.doc, filename)


if __name__ == "__main__":
    cse = ColoredStepExport()
    box = BRepPrimAPI_MakeBox(10, 20, 30).Shape()
    for i, face in enumerate(TopologyExplorer(box).faces()):
        if i % 3 == 0:
            cse.add_shape(face)
        elif i % 3 == 1:
            color = Quantity_Color(1, 1, 0, Quantity_TOC_RGB)
            cse.add_shape(face, color=color)
        elif i % 3 == 2:
            cse.add_shape(face, color=[0, 128, 255])

    cse.export("hogehoge.stp")

現状の問題点

面分ごとに1つの要素として出力されてしまっている？