# Can this be filleted faster in SubD?

I am fiddling with this organic hinge as an exercise. When done in NURBS, the fillets need to be manually done and it’s fiddly (time consuming). The point is to see if sub-D can produce a smoother version of this shape in less time it would take me to manually add fillets.
NurbsHinge.3dm (190.1 KB)

Doing it in SubD seems almost trivial if the side edge of the ears tacks underneath (See shape on the left)
…But … if we want to the side edge of the ears to be flush with the side edge of the top, then I am having some trouble visualizing the technique to use (shape on the right). I end up with square on top than needs to somehow become inscribed to a circle again.

Is there a better approach ?
SubD Hinge.3dm (155.7 KB)

(PS. In Blender there is a “sphere” command that does this. Blender Secrets - Make selections Circular with To Sphere, Circle and Smooth tool - YouTube )

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Topology-wise, I would probably do something like this:

A similar thing could pretty easily be implemented as a Grasshopper (or scripted) workflow. Find the average or center point of the point selection and use it to draw a circle with the distance between its center and the nearest or farthest selection point as a radius. Alternatively, a circle could also be fitted through the selected points.
Then pull all the selection points to the circular curve.

Thanks for these tips.
Sure the topology you drew looks reasonable. How do you achieve it ? Which sub-D option on the Cylinder command gives you a top face like that ?

(PS. We don’t need creases. That was the whole point of this topic)

None, I’ve started from a 3 by 3 SubD plane and used a circle (red) as a guide to make it circular.

That doesn’t really make sense regarding the geometry that you seem to want to achieve with SubD modelling. Creases are less destructive than for instance introducing edge loops everywhere to achieve a similar result.

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You use “creases” to make fillets ?

Using @diff-arch approach of starting with a flat plane and rounding it seems to be getting somewhere.

Then it becomes a matter of strategic edgeloop placement, but end up with a few Ngons

SubD-FromPlane.3dm (140.9 KB)

No, your reference images didn’t really show any fillets. I may have misunderstood you. Edge Fillets are more of a polysurface thing though!

Here’s a workflow that might work better:

subd-workflow.3dm (2.6 MB)

Yes, exactly.

Got it. Thanks for the detailed layout. ( I thought you meant creases can be relaxed like in Blender )

Yes, the point of this exercise was to see if subD can produce a smooth version of the reference object in less time it would take me to go in and add manual Nurbs fillets to it wherever sharp edges are present.

If kept sharp, then subD is not needed. The reference can be made in Nurbs in mere seconds already. It’s the smoothness I am after.

Hi Thomas,
I moved your “concept” NURBS geometry to the origin and ran _QuadRemesh on it. Usually it finds a nice subd topology to start with…

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Thanks for giving it a go Jess. I see you opted for a hybrid approach.

Unfortunately not, no! I asked about such a feature some time ago, and it doesn’t seem like they are considering it for now.

I guess for me this would still be faster and more precise to do with Nurbs.

Yes, you can use `Bevel` kind of like edge filleting. The bevel distance gives you some control over the smoothing behaviour.

However, it’s as prone to produce undesired geometries, as it is to fail for polysurfaces. You often need to optimize or tidy up the geometry afterwards.

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