Brep Edge component gives me the same edges in different order sometimes

Hi all,

i have a question about the order of list generated by BrepEdge component.

it gives me the desired edges, but when i save, close, and open the .gh file again,

sometimes, not always but often, the order of the curves/lines are different.

i want to use specific edges, in this case i want the lens edge curve.

the definition i attached is quite messy :p the components are about in the middle top(grouped).

do i have to use some other components?

or are there any ways to make grasshopper understand how to pick those edges always in the same order?

thanks,

Matsui Minoru

Attachments:

20121221-4.gh, 253 KB
glasses.3dm, 35 KB

Replies to This Discussion

Permalink Reply by Hannes Löschke on December 27, 2012 at 3:51am

I see the curves in the order, you named them in the ListItem components. As long as the way you construct the BRep doesn't change, BRepEdges should give the exact same order of edges. Saving, closing and reopening the file doesn't change that order for me but i tired only a few times.

You might be able to narrow the selection down by exploding the BRep first and getting the edges of the surfaces.

Permalink Reply by Matsui Minoru on December 27, 2012 at 4:32am

hi hannes,

thanks for your reply.

as you mentioned it seems that it doesn't change when i don't change anything that supports that BRep. so i tried changing the parameters (for example t: thickness of lens) then boom the edge extraction starts changing every time i change the parameter.

i tried exploding but it didn't work...it gives me the same result as BRep Edge component.

Permalink Reply by Hannes Löschke on December 27, 2012 at 5:41am

Ok, so you need a defined way to create the outlines.

You have your lens splitting curve and want it to be projected onto the front and back face of your lens, right? Why not do exactly that. Thake your front and back section curve. Create separate RevSrfs for each and project the splitting lines.

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