Why no Booleans for Subd?

[eg1]

I always thought about the two technologies this way:

Subd: good for quick concepts, visualisations, organic shapes are easy.

Downsides: getting clean topology with radii, intersections/cuts are a pain and can become a surgery. Basicly exactly what NURBS is good at.

NURBS: great for precision, manufacturing, control over curvature etc., radii and boolean cuts/trims.

Downsides: organic shapes require a steeper learning curve and more time than quick subD usually.

Today I applied a radius to a Subd in Fusion 360 and cut a NURBS sketch into it by boolean difference. Isn’t this the best of both worlds? I used to think this was technicly impossible?

“Cuts” are always a thing in Rhino/Blender Subd: Using InsertPoint to define a line for a cut, results in more subd edges, changing the overall shape, which needs to be correted by more polygons, but more polygons mean harder to get smooth subd srf. Here is an example of someone trying to cut a primary shape: Sub D Wirecut If you could do trims/booleans the basic topology could stay unchanged.

Please bring this to Rhino Subd! Would be amazing!

P.S: Do you think proper Subd modelling (with option for bol and radii) could replace NURBS for organic shapes in production parts?

Edit: I know toNurbs exists..

[JimCarruthers]

Fusion is just doing “to NURBS” in the background of the history tree.

The whole point of SubD was an attempt to replace NURBS, it failed precisely because they can’t be trimmed.

[eg1]

Silly me, of course its toNurbs also…
Why does it handle radii on toNurbs parts soo well though?

[davidcockey]

Rhino 9 WIP has Knife, a new SubD command for inserting points into SubD models.

Rhino WIP Feature: Knife

In the Rhino WIP, we’ve added the Knife command to cut through SubD and Mesh objects. What is this Feature? Knife is a tool for quickly adding topology to your SubD or Mesh models by drawing polylines on it. It works like a cutter that allows you to create accurate face layouts in a few simple clicks. You can: Draw straight through the model to create straight cuts, or Draw segmented polylines that will snap to the closest edge. [image] Rhino’s traditional InsertPoint only affects f…

[davidcockey]

@eg1

Why does it handle radii on toNurbs parts soo well though?

Not sure what you mean by “it” - Fusion?

[JimCarruthers]

I mean booleans and fillets are all “Solid modeling” does, they need to work well or it’s unusable.

[Lagom]

Two SubD surfaces, after toNurbs and Trim with each other, respond to FilletSrf as expected.

[Gijs (Gijs de Zwart)]

@eg1
Also note that in the current Rhino WIP, FilletSrf has been significantly improved and will give you a filleting experience much closer to what you see in other packages, thanks to the Join and Continue across faces options

[Gijs (Gijs de Zwart)]

One other note: when performing booleans, split or trim on a SubD, the SubD gets converted to a Nurbs object without face packing. As you can see in the screenshot I made, there are more faces than necessary because of this.

Currently it is better to first convert your SubD to Nurbs. You can then keep facepacking on, and opt for better G1 continuity at star points.

The result will then look like this: