Are there any G2 continuity limitations at special points?


Just curious to know if there are some kind of “Star points” like in T Splines, as those had only G1 continuity.

Stay safe


I believe G1 will be what you’ll get with ToNURBS if that is what you’ll ultimately convert the SubD to. is the open item regarding some additional refinements for exceptional points. I’ve nudged it… thanks.

Hi Brian,

Thanks. My question was if modelling with the Sub tools in Rhino 7 will have to deal ( to avoid ) with some kind of singular points, like the star points in T Splines . One of the recommendations in T Splines was to avoid Star Points as they only allowed G1 continuity.

I bet the same logic will be true for Rhino 7 SubD to a certain degree when converted to NURBS. As SubD these points don’t appear to have any wobble at all though.

We recently finished a product with SubD surfacing, with star point, and we released for tooling and looks really good. We could see super tiny reflection changes in emap mode in Rhino but I think the polishing + texturing of the tool took care of it.

I do not recall if the final versions were Rhino SubD or Tsplines (we are using both) . @jsantocono can tell you more.

We started also testing Xnurbs, which I think will be great for some hard surfacing problems. And if we end up buying it, I’ll ask them to see if they can consider making a start-points repatch tool, for those cases where things are visibly not right.

Hi All.
I think we used T-Splines for the final versions, but Rhino SubD should work too.
As far as I know StarPoints are G1 continuity, but just in a very tinny area near the point (Rhino SubDs and T-Splines). As Gustavo said, Is not big deal. In most cases unnoticeable on the tooling.
My recommendation would be to use StarPoints only when are topologically necessary. And always try to place them on the flatter areas. More flat = less noticiable

Thank you for the explanations gents !
Stay safe

RH-55492 is fixed in the latest WIP