Offsetting a trimmed surface problem

Hi,

I'm trying to be able to offset the two shapes below, basically just -1 or -2 but it's not working and I'm not quite sure what's going wrong and how the offset is actually working.

The one on the left won't offset at all, while the shape on the right will, to about 5, then it stops working. What is happening that makes it not work? I would guess that it has to do with the shape folding in on itself or clipping itself as it gets smaller or bigger?? Anyone know exactly? And can anyone think of a a way how to be able to offset the shape on on the left?

Thanks!

Attachments:

testoffset.gh, 7 KB
testoffeset.3dm, 468 KB

Replies to This Discussion

Permalink Reply by David Stasiuk on June 6, 2013 at 3:54am

This has all the appearances of a bug to me. There are some workarounds that you can apply, but I think there must be something off with how the surface offset manages trims.

For example, if you offset your surfaces without "retrim offset" set to false, you get clean surfaces. Then, reapplying the trim gives you, for these particular surfaces, two separate outcomes. In the first instance, it returns an unbakable, invalid surface. Yet you can still extract the wireframe from this invalid surface and use it to split the untrimmed surface. It's odd. The second surface lets you simply apply the trim, and it gives you a fully valid trimmed surface.