2-Rail Sweep question

I want to make a simple 2-rail sweep from these 3 curves:

The rail curves are the same filleted polygon positioned at 2 different Z heights. The sweep curve is a simple 3 point arc with endpoints on the rail curves.

When I make the sweep I get this:

I did not expect the kinks at the fillets. Is there something I can do to get a smooth sweep with no bumps? Or is that just the way the sweep logic works?

Please see the attached GH file for details.

Attachments:

SweepTest.gh, 11 KB

Replies to This Discussion

Permalink Reply by Ethan Gross on November 23, 2016 at 10:50am

Hi Birk, you need to adjust the curve seams so they align with the profile curve.

Permalink Reply by Ethan Gross on November 23, 2016 at 10:52am

I'm having trouble uploading the file.

Attachments:

SweepTest2.gh, 12 KB

Permalink Reply by Philipp Siedler on November 23, 2016 at 11:18am

Actually, I like Ethan Gross version way better!

Permalink Reply by Philipp Siedler on November 23, 2016 at 10:53am

Hi there, it is because the kink of the curves are at other positions than the curve you use as section for your two-rail sweeping component.

cheers, Phil

Permalink Reply by Philipp Siedler on November 23, 2016 at 11:16am

Well there you go. See if it makes any sense to you.

cheers, Phil

Attachments:

SweepTest_pds.gh, 10 KB

Permalink Reply by Birk Binnard on November 23, 2016 at 12:03pm

Wowee! Many thanks for such great solutions.

I have never been really clear on what the GH Seam object really did, or even what is meant by the concept of the seam of a curve. Maybe there should be some sort of graphical way to do a "show seam".

I can see that Ethan's solution causes the (invisible!) seams to line up, which then makes the Sweep function happy. Now I am happy too!

Thanks again for helping me out. There sure is a lot to learn in the world of Grasshopper.

Permalink Reply by Ethan Gross on November 23, 2016 at 1:17pm

I'm not a great fan of seams myself but I guess you have to have some way of knowing where you are on a closed curve.

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