topic Re: Spline modeling donut in 3ds Max Modeling Forum

Spline modeling donut

Danmitch1 — Mon, 09 Mar 2020 21:07:56 GMT

Hi, Its possible that im searching for the impossible but can you apply a surface modifier to a donut (converted to an editable spline) without it filling the inner circle?

Im trying to build a tube

Re: Spline modeling donut

10DSpace — Tue, 10 Mar 2020 02:00:35 GMT

@Danmitch1

Is there a reason you don't you start with the tube primitive and convert to an editable poly?

You can also convert the donut shape to an editable poly and extrude the donut poly.

Either way you get to a similar place depending on the number of segments you select for the tube.

Re: Spline modeling donut

Danmitch1 — Tue, 10 Mar 2020 14:30:17 GMT

My goal (perhaps impossible) was to create a model 100% using splines with surface modifiers.

I realize I could finished the model and use a Boolean subtraction to cut the hole but like I said, I wanted to complete the model 100% out of splines and surface mods. Maybe not possible?

Thanks for your reply!

Dan.

Re: Spline modeling donut

10DSpace — Tue, 10 Mar 2020 15:20:03 GMT

@Danmitch1

Sorry, but if you are insisting on the constraint of no other tools in max other than spline and surface, then I do not know a way to do specifically what you want to do. The surface modifier seems oriented to completely covering external surfaces of spline cross sections and I do not know a way of specifying selective coverage (and in your case, selectively changing/flipping normal direction across individual segments) to guide the surface modifier away from complete coverage with a single surface normal orientation for the entire surface. That is where I would reach for editable poly modeling tools, personally. Maybe someone else here knows a way with spline and surface tools alone.

Re: Spline modeling donut

Danmitch1 — Tue, 10 Mar 2020 16:51:38 GMT

Yeah thats what I was afraid of. I was thinking it was a threshold thing but if I increase the threshold of the surface, parts I want a surface on start to disappear..

There must be a way of creating holes in the surface other than converting to editable poly.

Thanks for your input!

Dan.

Re: Spline modeling donut

10DSpace — Tue, 10 Mar 2020 19:17:49 GMT

@Danmitch1

There must be a way of creating holes in the surface other than converting to editable poly.

Well in thinking further about the issue, if you separate the donut into left and right and inner and outer halves,

then the surface modifier will leave the hole you want.

You could then use a copy of the individual donut sections with cross sections created from outer to inner to cap the top. This gets around the surface modifier's behavior of closing the entire surface, because essentially you are surfacing cross sections based on arcs which are not closed shapes. Hope this helps.

Re: Spline modeling donut

Danmitch1 — Thu, 12 Mar 2020 19:00:11 GMT

Thanks for your efforts, as this is a good solution i failed to mention this is to be 3d printed. It will need to be one mesh.

Re: Spline modeling donut

leeminardi — Thu, 12 Mar 2020 19:45:55 GMT

Convert the outer spline profile to a NURBS then attach the inner profile. YOu can then add the Extrude modifier and the shape will be capped.

Note, an editable poly can be saved as an STL file for 3D printing.

Re: Spline modeling donut

Danmitch1 — Thu, 12 Mar 2020 20:40:23 GMT

Oh ok, that would work then. I was wanting to stay out of editable poly mode and use only splines for super high poly modling while not choking the pc with millions of polys on display. Plus curves are much nicer and easy to create using splines.

I was watching this Youtube video and couldn't figure out why my version kept capping the top and not his until rewinding and really following step by step.

Turns out I started with a circle spline while he started with an Ngon. That was all that I needed to do..

My question now is why?? Because of the extra vertices?