I should add, there is a built-in command from XSI 1.0 called "PolyMeshPNet"
that never officially saw the light of day as it was unfinished, but is still
accessible in the SDK to convert polygons to NURBS Surfaces. Each polygon of
the source mesh is converted into a 2x2 NURBS Cubic surface and assembled into
a SurfaceMesh with continuity control. It can be feasible for simple
conversions like strips, but not recommended for anything more than that.
If you want to try PolyMeshPNet, select a (simple) polygon mesh and run the
following command from the script editor:
ApplyOp( "PolyMeshPNet", Selection(0), siUnspecified,
siPersistentOperation );
I would advise selecting and extracting edges from the polygon mesh, then loft
them into a surface. When the curves are extracted, do a 'fit' operation to
convert to Cubic, but make sure to activate 'maintain continuity', then set
subdivisions to 1. This will tell the fit tool to use the same number of
points as the input curve. Once the fitted curves are generated, loft them
into a surface. Just keep in mind the surface won't exactly fit the shape of
the polygon mesh because the loft tool will try to use control point positions
and/or adaptive fitting which may cause some points to shift.
To do a true polygon to NURBS Conversion while retaining the shape and point
positioning, you'll need to write custom tools which use knot positions instead
of control point positions to loft the curves into a surface.
Matt
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Matt Lind
Sent: Friday, August 22, 2014 10:50 AM
To: [email protected]
Subject: RE: Polys to Nurbes
King of NURBS?
I started in the industry during an era where NURBS were the norm and polygons
feigned because, to answer a question from another thread, if you need
interactive performance on high resolution rigs, NURBS will update
significantly faster than polygons (assuming no trims/blends/filets/etc...).
That's largely why they were used back in the day. With the introduction of
subdivision surfaces in the late 1990's (or subdivision smoothing), artists
started shifting away from NURBS to polygons. But I digress.
I do have many self-written tools for NURBS going to/from polygon mesh, lofting
based on knot positions instead of control point positions, and so on, but I am
not sure if I can share them as they may be considered my employer's property.
There is a little known tool in the SDK which will convert polygons to a NURBS
Net.
Matt
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Eric Thivierge
Sent: Friday, August 22, 2014 9:59 AM
To: [email protected]
Subject: Re: Polys to Nurbes
Surely Matt Lind (King of Nurbs) has to have something... :)
Eric T.
On Friday, August 22, 2014 12:31:11 PM, Sebastien Sterling wrote:
>
>
> Hello everyone, i was wondering if there is a method or more likely a
> tool out there that could convert polygon strips into nurb /surface
> strips. surely something like this exists.
>
> All the best
>
> - Seb
