.obj into brep.

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Permalink Reply by David Rutten on November 8, 2010 at 1:06pm

Hi Thibaut,

you cannot use any of the importer plugins via Grasshopper. You can either import the object manually or script this (not that easy). You could even choose to parse the file directly.

The other bit of bad news is that there's no Mesh->Nurb component in Grasshopper.

Can you tell us what exactly you're trying to accomplish? From the look of things so far it seems this would be easier to accomplish manually or maybe with a RhinoScript...

--
David Rutten
david@mcneel.com
Seattle, WA

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Permalink Reply by Benjamin Golder on November 8, 2010 at 1:21pm

Hi Thibaut,

The Local Code plug in will allow you to import .obj files into Grasshopper, but if it is a mesh, then you'll still have to figure out how to convert it into a brep.

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Permalink Reply by tib ctrl on November 8, 2010 at 3:14pm

Hi thanks for your replies.
David,
I had previously created a precise shape in grasshopper. Unfortunately I don't have the definition any more, but I had baked the object in rhino so I still have a .3dm and obj. file.
Today, I need to achieve boolean operations between this shape and other ones that I'm about to create with grasshopper.
That's why I tried to get this geometry back in grasshopper.

Is brep conversion, the only way to achieve intersection operations?

Benjamin,
The local Code plug in seems to be handy.
I heard about an external component using t-splines to perform a mesh to brep component.
http://www.tsplines.com/forum/viewtopic.php?f=9&t=29673
I do not own the t-splines plug-in at the moment, but before purchasing, I wonder if it's the right tool.

thanks again..

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Permalink Reply by Andrew Heumann on November 8, 2010 at 7:55pm

If you can get the obj file into rhino with the localcode plug in, here's a definition that does the rest of the job - takes a mesh and converts it to a brep with one surface per face, with results equivalent to the MeshtoNURB command.

If your goal is intersections however, you might have better luck simply performing mesh booleans - giant many-faceted polysurfaces like the ones produced by this definition are likely to be unwieldy.

Attachments:

• Mesh_to_BRep.ghx, 810 KB

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Permalink Reply by tib ctrl on November 9, 2010 at 6:36am

A great thank, it works perfectly.. Time for for me to study your definition....

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Permalink Reply by tib ctrl on November 9, 2010 at 7:58am

Sorry, a tiny problem is still remaining. the converted brep does not seem to be closed.
how could I make it closed in order to use the brep volume component or make some intersections?
thanks one more time.

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Permalink Reply by Andrew Heumann on November 9, 2010 at 7:31pm

If the input mesh is closed, the resulting BRep also ought to be. Is this not the case? If you can upload the particular mesh you're using I can take a look.

If the openings remaining on the output BRep are planar, you can use the "cap" component to fill in the faces. Otherwise you are probably going to have to do some mesh editing directly in rhino before converting - FillMeshHoles, etc.

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Permalink Reply by Firat Aydin on July 18, 2012 at 12:35am

I HAVE BEEN DOING SOME SURFACIAL COMPARISONS WITH BREPS.

HOWEVER, IT DIRECTLY CONVERTS THE MESH IN TO BREP WITH ITS SUBSURFACES COMPOSED OF NODES.

THAT PREVENTS ME FROM DETECTING THE CORRECT SURFACE.

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