Understanding Revolution and Untrimmed Surfaces

Grasshopper
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1

Pretty simple question:

See the attached GH file.
Revolution-UntrimmedSurf.gh (17.0 KB)
When I revolve a closed curve, the resulting geometry is an “untrimmed surface,” but not the expected “closed brep,” as demonstrated by the capped extrusion.

I would think that “Closed Brep” would be the priority definition of a geometry, as it’s better to know whether you’re working with a brep or a surface. Is there something about this revolution geometry that is making it fail the “closed brep” definition, or does it fit the definition but its “untrimmed surface” label takes higher priority?

Baking creates a solid with no naked/non-manifold edges.

2

Haven’t opened the file but a Brep means that the object consists of more than one surface / face.

3

Jeez, thanks Michael, do I feel foolish…my simple mind just assumed that it was the equivalent of a solid.

4

Hi @jasongberger, @Michael_Pryor - both surfaces and polysurfaces, eiher trimmed or untrimmed, are added to the Rhino document as Breps. Your real question might be whether or not the Brep contains a single surface or multiple surfaces.

– Dale

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5

Yeap understood, I believe what he is talking about is what a GH panel outputs as the geometry description. In his case it output a description as “untrimmed surface”. GH outputs a description of Brep if it is not a single surface geometry (trimmed or untrimmed).

6

Unless it’s a box :wink:

7

Depends actually if it is generated as box type or if it is a joined set of surfaces that looks like a box, but yes there are other types of geometry.

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