MaxScript: Can't Undo Scripted Spline Operations?

Sword of Apollo

I'm working on a script that moves vertices/knots of an editable spline, and I want to allow the user to undo the operation. I have used theHold successfully for a script that moves vertices on editable mesh/poly objects, but when I attempt to use it for splines using setKnotPoint, setInVec and setOutVec, it doesn't work.

The actual script I'm working on is a bit complex, so I tested theHold on the simple spline flattening script in the MaxScript help:

theHold.Begin()
new_z = $.pos.z
  for s = 1 to (numSplines $) do
  (
    for k = 1 to (numKnots $ s) do
    (
      knt = getKnotPoint $ s k
      in_vec = getInVec $ s k
      out_vec = getOutVec $ s k
      knt.z = in_vec.z = out_vec.z = new_z
      setInVec $ s k in_vec
      setOutVec $ s k out_vec
      setKnotPoint $ s k knt
    )--end k loop
  )--end s loop
  updateshape $
  theHold.Accept "flatten spline"

The "flatten spline" doesn't appear in the undo space in the Edit menu. Does that mean that these operations can't be undone, even though manual moving of spline vertices can? Is there an alternative way to move the points that allows for undo?

Thank you for any help.

LoTekK

This is from 2009, so I guess they still haven't sorted it out:

http://forums.cgsociety.org/showpost.php?p=5720688&postcount=4

This is a long standing issue with maxscript, spline operations do not generate undo entries..
A way around this limitation is to create a copy of the spline, modify the copy, replace the original spline with the copy, and then delete the copy. All within a single undo context obviously.

Mark Dygert

Wow... they still haven't fixed that... sigh.

Sword of Apollo

Thanks. I did a google search for this problem before I posted, but couldn't find anything. It seems a little ridiculous that this has been a problem for over 3 years and they still haven't fixed it. I know there's generally more involved to a fix than an outsider would imagine, but it's still hard to believe. I guess I'll have to use the work-around, annoying and unsatisfying as that is.

Max 2013 is supposed to fix a lot of minor, annoying issues. I would hope this would be one of them.