getting the exterior and interior curves from surfaces

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Permalink Reply by Joseph Oster on May 15, 2017 at 9:03am

Projecting the 3D breps to a plane results in many duplicate lines because the top and bottom surfaces of each brep generate their own curves.

I would examine each brep, isolate the bottom surface of each one and project only that surface to the plane, like this:

This results in one or two curves per original brep.  Easy to determine which one is inner vs. outer...  But there is some overlap?  And if you want a large joined surface with multiple holes, there is more to it.

Attachments:

• Lasercut_2017May15a.gh, 2 MB

Permalink Reply by kaveh dadgar on May 15, 2017 at 1:49pm

it was great help joseph. but only on more thing. still i dont know how to determine which curve is the inner one and which one is the outer one of these cells?

Permalink Reply by kaveh dadgar on May 15, 2017 at 1:54pm

I've just got  my answer. the second item in each branch was the voids and the first one was outer curve for each cell.
thank you so much joseph.

Permalink Reply by David Rutten on May 15, 2017 at 2:37pm

There's quite a lot of topological information in breps that is not accessible directly from GH.

The attached C# script exposes some of this. It focuses only on Trims and Loops. It ignores vertices, edges and faces entirely.

Note that the Loops2 output is hidden even when the component is visible in the preview.

Attachments:

• brepedgeextractor.gh, 47 KB