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Shape Type of Compounds with All Geometry Children

Modeling Data and AlgorithmsSun, 02/16/2025 - 23:532 replies

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QuestionAuthor

As you can see on screenshot and step file in zip archive, Wood Top is a sub-assembly with only solid/geometry based children. If I try to get its type name with TopoDS_Shape::ShapeType(), it says COMPOUND

But using these two return false.

bool bHasChild = TDF_Label::HasChild();

TDF_LabelSequence Children_Counter;
this->Assembly->GetComponents(Referred_Label, Children_Counter, false);
bool bHasChild = Children_Counter.Length() > 0;

I need to differentiate between a sub-assembly with actually zero children and with only geometry based children. Is there any suggestion for that ? Shouldn't ShapeType() return COMPSOLID ?

Discussion

2 archived replies

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01Commenter-1

TopAbs_COMPSOLID means 'Composite Solid', not 'Compound of Solids'. Within composite solid, solids should share common faces where they touch each other. But if we'll take a look at 'Wood Top' within your model, we'll see no shared faces.

pload OCAF XDE VISUALIZATION
ReadStep D test_1.step
XGetShape s D 0:1:1:1:1
whatis s
# s is a shape COMPOUND FORWARD Modified
explode s
# s_1 s_2 s_3 s_4
whatis s_1
# s_1 is a shape SOLID FORWARD Modified
vdisplay s_1 s_2 s_3 s_4 -dispMode 1
vfit
vaspects s_1 s_2 s_3 s_4 -faceBoundaries 1
verase s_2 s_3 s_4

You may see that the main solid doesn't share common faces/wires with other solids in compound.

Archived image: wood_top compound Archived image: wood_top main solid

02Author

So, how can I differentiate wood top like object and a sub-assembly which doesn't have a child with C++ ? I am working on Unreal Engine 5 wrapper and I need to know that when should I create scene component or static mesh component