Closest Spline & control points loop in both directions

[_Aka_]

but I am using "output" only to draw nearestPoint. NextControlPoint and PreviousControlPoint is based on a "nearestSegment".

Hi again

Sorry my previous message didn't make sense. I wrote it in a hurry knowing that I could not write a long one until now. Now that I am free again, here is the right answer:

It all boils down to the concept of a segment. A segment is the curve between two CPs. In Curvy Splines the choice was made to represent a segment in the code with its first CP. So the curve between CP1 and CP2 will be represented by CP1.
So when you call GetNearestPointTF:

• on any point between CP1 and CP2, the returned segment is CP1
  
• on CP1, the returned segment is CP1
  
• on CP2, the returned segment depends on whether there is a CP3:
       - if CP3 exists, that means that CP2 is a valid segment (the curve between CP2 and CP3). In this case the returned segment is CP2
       - if CP3 does not exist, that means that CP2 is not a segment, so the returned segment is CP1
  

Try visualizing your gizmos on an open spline, I think that my explanation will make sense. If you do so, handle the fact that NextControlPoint or PreviousControlPoint can be null if you are on the edge of the open spline.

I hope this helped.

Have a nice day