Offset surface


I’m trying to offset a surface but the component doesn’t work as uual on this ocasion, I guess is due to the curavature of the surface, but I can do it in rhino, so there must be a way to do it.
I tried to flip the surface and to add the expression -x in the offset component, but none of those work fine.

Any suggestions?


offset (32.5 KB)

It works without a problem.

offset (32.6 KB)

You can’t offset with more than -0.5 and try Pufferfish Offset surface

Hi Kim;

It works if you as a regular offset, but don’t if you want to offset on the opposite direction.
I need to offset it on the other way.
Seghier suggested to apply a component of the Pufferfish , but that creates an “odd” surface.

Is there any way to make it possible. I was thinking on create a grid of points on the surface, evaluate them on the surface to get the normal and move them on the opposite direction and make a surface from those points, but have no clue of how can I generate the grid of points on that surface .

Is what I’m thinking even possible ?




it doesn’t work because the retrim option is on true, but your inner offset is too big, so it inverts the surface which results in not holding the trim anymore. If you disable retrim you see why.

Its potentially a bug, because it doesn’t throw an exception, but instead returns null. Which is not good but it is not an error per se, since you can’t create an trimmed offset with this parameter as Seghier pointed out.

Thanks Tom for your replay.
If I offset the untrim surface what I get is a polysurface. I tried to decompose that polysurface in order to choose the right surface and trim it again as the original to get what I want, but th thing is that by decomposing it I get now two “odd” shape surfaces on which I cannot trim to get the surface I need.
Do you know if what I suggested to Kim is possible?offset (75.2 KB)

Seghier suggested to apply a component of the Pufferfish , but that creates an “odd” surface.

It creates the same surface Rhino does. If you build that surface correct in the first place without trims then in should be fine. It has 4 edges so it can be made as untrimmed.

Hi Michael,

I apologize, I did not want to mean that is due to Pufferfish. Yes, you are right, if I try to offset that surface with rhino creates the same result, so the word should be “undesired” surface instead of “odd”, sorry about that, and I’m pretty sure that there is a consistent reason, perhaps the curvature of the surface near the edges, I don’t know.
What I’m trying to get is and offset of 1,50 mm opposite to the normal of the original one, If I offset the original untrimed surface I’m getting a polysurface that I cannot trim to get the same result as the original trimed one at a 1,5 mm distance as you can see on the attached file of my previous message.
Michael, do you know if what I suggested to Kim is possible ?

Thanks, and sorry again for my bad explanation of the issue.

no need to apologize, you did nothing wrong. I am just clarifying that this issue is with offset in general and I think it is to do with trimmed edges in this case.

Try this , you can make it better

offset surface (2).gh (72.2 KB)

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Hi Seghier,

Thanks, that’s what I need.
Now I will try to adapt your definition for another situations, for not such a straight trimmed surfaces.

Thanks so much

offseting, always a joy :skull_and_crossbones:

how come you didn’t show that result?

That’s a good idea but because of the irregularity of your surface and because it’s untrimmed, then you’d run into some bugs…maybe, maybe not, which you can deal with later using a rebuilt untrimmed surface :slight_smile:

Another alternative here is perhaps looking into tween surfaces? Which aren’t offsets, I know, but maybe if you don’t care?

In this example a few twins are created (after creating an untrimmed surface) then you can pick one as long as it’s in the distance/shape you intended.

Check the attached if you want
offset (49.9 KB)


is that tween srf component native? or old Pufferfish? (can’t open it now)


thanks for bringing that up, it was the old component, but I wasn’t trying to use the plugin, so here’s with tween curves (is tween curves native? :joy:):
offset (52.5 KB)

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