Hi Fredrik, I've added that to the wishlist. That would be a kind of "vertex" based filleting for surfaces (and I suppose corner points of solids as well).

One big problem is that the most basic kind of fillet is a circular arc fillet, and it generally isn't possible to fit a circular arc to be simultaneously tangent to 2 non-planar curves.

So what would you expect to have happen in there if you had the Fillet shape set to Shape: Circular, which is the default?


> -since the surface has its own coordinates (u and v)

The problem is that distances in the UV parameter space do not correspond directly to distances in 3D space. When working in UV space you tend to have to do things like adaptive fitting processes to match 3D space distances, it is not just a simple matter of drawing in 2D/UV and then you're done. That tends to make this kind of stuff far more difficult than what it would initially seem.

- Michael

Hi Manz - one thing to notice is that if you fillet the corner of a shell like that, you don't actually get an arc on the bottom final piece, the fillet will end up being trimmed there.

So for example this edge shelled and filleted:



If you shrink the fillet surface down and show control points, you can see the fillet is trimmed along the bottom, the resulting curve on the bottom piece is not an isoparm of the fillet (the isoparms are arcs):



It's a curve that is the result of an intersection between the fillet and the bottom surface.

I guess that may be a reasonable thing to put in there for a surface corner vertex fillet with shape=circular, but I'm not really sure if I have an easy way to calculate that particular thing shy of doing the actual shell + fillet...

- Michael

One thing that I will probably be able to do sooner than this is to have a "distance based" fillet option instead of rolling-ball radius based.

- Michael

number of points is given by the meshing parameters options or it's absolute number calculate by the nurbs itself with the curve object used?

Hi Pilou - I'm not sure if I understand the question - which number of points are you asking about, is it in my screenshot above?

That is showing the control points that define the fillet surface, that is not a mesh calculation showing there.

Fillet calculations add as many points as necessary when creating the fillet surface to make it follow the intersection curve and within the distance tolerance, so that the fillet should not deviate more than 0.001 units from the adjacent surfaces.

- Michael

yes this one ;)

Why they are not equal spaced as it's along a straight line?

Hi Pilou,

> Why they are not equal spaced as it's along a straight line?

I'm not sure of the precise reason in this case. In general filleting involves intersection between offset surfaces which is often a tolerance and adaptive based computation itself.

During that offset process, certain areas happened to get fit closer to the ideal result than others, resulting in fewer points in some areas.

It is not always easy for the algorithms to understand that a simple result can be possible especially when the surfaces involved are general curved surfaces and not primitives like cylinders or spheres.


If you need to get the most simple fillet construction possible, you may be able to get better results with a solid modeler like SolidWorks or something like that. They have generally spent more time making special case handling for more types of situations.

- Michael

< If you need to get the most simple fillet
oh no, it was just by curiosity :)

Hi Michael'

Thank you for adding it to the wishlist.


>and I suppose corner points of solids as well

Yes good idea!

>One big problem is that the most basic kind of fillet is a circular arc fillet, and it generally isn't possible to fit a circular arc to be simultaneously tangent to 2 non-planar curves.
>So what would you expect to have happen in there if you had the Fillet shape set to Shape: Circular, which is the default?

Ok, in this case the circular option might have to e grayed out and not possible to click.
Or maby another option can be added in the fillet tool that does the "point fillet".

-Fredrik