Closed Breps

Replies to This Discussion

Permalink Reply by ng5 Alex on June 23, 2014 at 6:02pm

Hello

please attach gh file.

Permalink Reply by BC on June 23, 2014 at 6:18pm

Last images + GH file.

Just a headsup, the GH file is a cluster within a larger GH file. I only saved out the cluster, but I'm not sure if it works as a stand-alone. If thats the case let me know and I'll put up the whole thing.

Attachments:

• 4.PNG, 300 KB
• 5.PNG, 307 KB
• Help1.gh, 12 KB

Permalink Reply by ng5 Alex on June 23, 2014 at 6:46pm

it does not work and i can not recreate the geometry or the definition that's missing.

my best guess would be that you are trying to join untrimmed with trimmed surface.

Permalink Reply by BC on June 23, 2014 at 7:06pm

Hi ng,

I think that's probably the case. Is there a way to shrink the extents of the trimmed surface (similar to the ShrinkTrimmedSrf command in Rhino) that would allow these to come together as a solid brep?

-BC

Permalink Reply by BC on June 23, 2014 at 7:10pm

Here's the full GH file attached. Problem cluster is circled in red.

Attachments:

• Help1.gh, 100 KB

Permalink Reply by ng5 Alex on June 23, 2014 at 7:31pm

Hello turns out i was wrong. it is possible to join trimmed and untrimmed surfaces to a closed brep.

i tried what i think you are after in another way and it works. i have not found what was the problem with your cluster, but could have something to do with the boundary surface, which is the component i did not use and used loft instead for the appropriate curves.

hope that helps

cheers

alex

Attachments:

• Help1(2).gh, 99 KB

Permalink Reply by ng5 Alex on June 23, 2014 at 7:45pm

ok i found it.

the cluster uses for the top ellipses to boundary them, but this surface cannot be joined to a closed brep with the rest of the geometry you have, which is a product of lofted arcs, that are dependent to the division of the ellipses. if you bake the ellipse boundary and the geometry you can see the obvious hole.

so to have your cluster doing it right you either do it like i suggested or solve an intersection on the upper part to, like you did with its base, to make sure the curves are part of the geometry.

did my best to explain it. must sleep soon. :-)

cheers

alex

Permalink Reply by BC on June 23, 2014 at 8:20pm

Alex,

Wonderful, thank you very much. I appreciate the explanation as well, as I'm still somewhat new to GH and am trying to process the "why" just as much as the "how". On that note though, Im a little confused by it.... do you mean that with the ellipses, they needed to go (in order) Move > Offset? to ensure proper joining?

Permalink Reply by ng5 Alex on June 23, 2014 at 8:25pm

no it is just that the top ellipses are not part of the loft (that is generated from the arcs, that are generated from the division of the ellipses) so they can not be joined. that is why i extracted the top naked edges of the lofts.

i suggested to bake them, because it is tricky to see the fault through grasshopper preview.

Permalink Reply by BC on June 23, 2014 at 8:27pm

Ok, got you. So even though they originated from the same geometry but went through "x" changes, they need to refer back to the original geometry no matter what (is how I'm reading it)?

Permalink Reply by ng5 Alex on June 23, 2014 at 8:33pm

this happens because you are working with loft that comes from the arcs.

so to get close to the initial ellipses you will have to divide them as much as you can so that you have many arcs trying to describe you ellipses. otherwise loft works its magic  interpolating from arc to the other and making a loft that does not follow the ellipses.