Wish - Insert control point ~ single span


(Rob McPherson) #1

Wish - I’d like to have the option of inserting a control point to a single span surface and retaining its single span status. Currently it makes it multispan only.

This can of course be achieved by changing the degree using changeDegree command, but this automatically re-shuffles the control points for you. I’d like the existing structure to remain while the only things that change are the degree and my new chosen control point location.

Regards,

Rob.


(David Cockey) #2

The shape of the surface will change unless the other control points move. That’s how the math works.


(David Cockey) #3

Procedure to increase degree of a single span surface while retaining as single span and not changing the shape:

  1. InsertKnot to insert number of “knots” equal to desired increase in degree in each direction (1 inserted knot for each increment of degree increase). Important: InsertKnot will add control points but not change the shape of the surface. InsertControlPoint will change the shape of the surface.

  2. ChangeDegree to change the degree as to one greater than the number of control points in each direction. Use Deformable=Yes Control point location will change and additional control points may be added. They will be removed in the next step.

  3. RemoveKnot to remove interior knots on the increased degree surface.:


(Rob McPherson) #4

Of course the shape changes, retaining the shape is not what I’ve asked for. Retaining the control point structure is however what I’m requesting.

Regards,

Rob.


(Rob McPherson) #5

Interesting, so making it multispan first by adding the knot and then removing after. I’ll give that a try.

(edit) Had a go at that but it too shuffles the control points around and with the extra steps it’s more work than just running the changeDegree command and then moveUVN after. Bearing in mind the control point structure and single span-ness of the surface is what I’m trying to achieve not keeping the original shape of the surface itself - perhaps my original post wasn’t explicit enough in that regard!

Regards,

Rob.