Change a point to a curve or corner point as in Macromedia Freehand years ago

In the '90s I did lots of design work using Macromedia Freehand. It was a beautiful and very functional program. Adobe bought it’s competition and shelved it. I can rant about this at another time. There were a few drawing tools in Freehand that I wish Rhino employed. Maybe the commands exist, but I have not found them.

One of the commands that would be very handy in Rhino is to change a point from a corner point to a curve point and vice versa. That is, a curve point cannot be bent at an angle. It always keeps linear integrity at the point. The curve controls on either side of the point could influence the curve after passing through the point but there would never be a sharp bend at the point. It appears there are related tools in the SubD commands but I need them with simple line drawings. Any ideas?

Hello - no- Rhino uses Nurbs for freeform curves, these are more generally useful in 3d modeling, illustration tools typically string together Bezier curves - the ‘corners’ are between Beziers. You can ‘get there’ in Rhino, but it is not a super clean process:

InsertKink can be used on a Nurbs curve to introduce a ‘corner’ anyplace - snap to knots to locate the illustrator-like locations, and RemoveKnot at corners to smooth them out.


Thanks Pascal. InsertKink and RemoveKnot work just fine. Not exactly the same but close enough. Are a kink and knot the same thing? What is the correct name for a non-kinky curve point? Pardon my ignorance but when is a knot created on a curve vs. a curve point? A simple circle, for instance, has knots at the 90 degree points but the other points are not knots, but continuous curve points as in Freehand. Is there a way to insert a curve point instead of inserting a kink?

Hi Walter - knots and kinks are related but not the same - kinks are located at ‘fully multiple’ knots - where there are degree number of knots piled up. (The quadrants on the circle for example ) The control point at a kink is always on the curve, not off of it.

You can think of knots as ‘tying together’ Bezier spans - if you ConvertToBeziers a Nurbs curve, it will divide at the knot locations.

Control points are not the same as knots… However, you can use InsertKnot to add complexity - a knot is added at the specified location and a control point is added ‘where ever’ such that the curve shape does not change) without changing the curve shape, or InsertControlPoint to insert a control point at a the specified location and a knot is added ‘where ever’ such that the control point can go where you said… the shape of the curve will likely change.