I draw a big box and a small box by another CAD software.
The big box contained the small box. These two boxes are not intersect each other.
I combined these two boxes into a solid model and saved as step file.
When I import this step file into Rhino I got a block instance ,and I want to know how can I get B-rep data from block instance?
When I get a block instance, I used to explode and join the model then I can use GetObjects() to get CRhinoObject.
CRhinoObject convert to ON_Brep.
but this model will become two boxes after explode, then I can not join them .