Hi,

A conner appeared when I converted a square to NURBS.
I can't see any different attributes value on points, vertex or prims.
Why?
Any hidden data that not displayed in spreadsheet?
Thanks!

that's the joy of working with NURBS

jerry7
I can't see any different attributes value on points, vertex or prims.

look at "knots" prim intrinsic

one way to get continuity is appending Ends SOP (Open) + Ends SOP (Close Rounded)

jerry7
I can't see any different attributes value on points, vertex or prims.
Why?

Because you haven't changed the values/positions of the points.
What you have done is 'ask' to create a nurbs curve using those point positions you haven't changed.

A nurbs curve is based on a function whose input positions define how the curve will get shaped.
It's not a polyline/polygon where the point/vertexes define the segments start/end positions.

In your example the corner is both the start and end of the line so it will always be a 'corner'(with one exception of being able to make a tangency,e.g. move point 1 and 3 to have their axis run through point 0) because there is no 'space' or
continuation of the line between the start and the end; Hence no controlling point inbetween to define the shape of the curve like the rest of the curve is constructed.

Point 1 defines the most strongly how the curve will shape coming from point 0 and going to point 2, point 2 defines the most strongly how it will curve from point 1 and to point 3....with point 3 defining the most strongly how the curve goes into the end of the curve at point 0.

Try this: Always keeping pt1/pt3 axis going through pt0, move pt1/pt3 to different positions and distances from each other, you will always get a smooth continuous curve with no corner. That's because you are keeping the same tangency for both the start and end of the nurbs curve.

Thanks for replies!
Could one set knots vector explicitly?

jerry7
Could one set knots vector explicitly?

You can potentially use Basis SOP that allows manually setting knots, even though I'm not really sure what knot sequence represents as sometimes it looks like indices and sometimes more like weights between 0 and 1