Can't get TDF_Label from TopoDS_Shape (version OCC 7.5.0)

HSIEN-SHUN HSU
Mon, 04/25/2022 - 15:31

Forums:

Hi everyone! As for the title, I want to get the TDF_Label from TopoDS_Shape, so I use the XCAFDoc_ShapeTool::FindShape, but it doesn't work, there is my code:

// Get shape
TopoDS_Shape shape = myAISContext()->DetectedShape(); 

// shapeL gets from TDoc_Std_Document::Main()
Handle(XCAFDoc_ShapeTool) myAssembly = XCAFDoc_DocumentTool::ShapeTool(shapeL);

// becasue I know the type of shape I choose is edge, so I transform to TopoDS_Edge
const TopoDS_Edge edge = TopoDS::Edge(shape);

TDF_Label aLabel = myAssembly->FindShape(edge);

if (aLabel.IsNull()) 
{ 
    cout << "No Label" << endl;
} 
else
{ 
    cout << "Get Label" << endl;
}

And the result returns always "No Label".

Could anyone help me? Thanks.

HSIEN-SHUN HSU
Sun, 05/01/2022 - 17:18

Thanks, everyone, I solve it by myself. There is my code:

TCollection_AsciiString findName(const TDF_Label& theLabel,  Handle(XCAFDoc_ShapeTool) aShapeTool, const TopoDS_Shape& shape)
    {
        for (TDF_ChildIterator Father(theLabel, Standard_True); Father.More(); Father.Next())
        {
            TDF_Label Child = Father.Value();
            if (aShapeTool->IsShape(Child))
            {
                TopoDS_Shape aShape = aShapeTool->GetShape(Child);
                if (shape.IsSame(aShape))
                {
                    TCollection_AsciiString node;
                    TDF_Tool::Entry(Child, node);
                    return node;
                }
            }
        }

        return "null";
    }

Mikhail MPV
Wed, 05/04/2022 - 10:09

It is hard to understand the source of the problem in your initial example, because we don't know the content of original file and the shape you have got from AISContext. I may only guess that the problem in the second argument of FindShape method. "findInstance = Standard_False" by default, so, it removes the location of the searched shape. Perhaps, if you set it to True, it will work in the same way as your method, but in some more optimized way.