Convert Ploy to spline

And this is the same but here you have the possibility to change each option separately.
I think this is actually what you're looking for.

fn polyToSpline obj splName: thickness: sides: visInRender: visInView: wireclr: =
(
if selection.count == 1 and classof obj == Editable_Poly do
(
max create mode
with redraw off
(
edgesCount = obj.edges.count
polyOp.createShape obj #{1..edgesCount} smooth:false name:splName
ps = $PolySpline ; ps.wirecolor = wireclr ; ps.thickness = thickness ; ps.sides = sides
ps.render_displayRenderMesh = visInView ; ps.render_renderable = visInRender
updateshape ps ; ps.name = uniquename ps.name ; select ps
)
)
)
polyToSpline $ splName:"PolySpline" thickness:0.3 sides:12 visInRender:on visInView:on wireclr:orange

thanks for reply, actually i looking for script like miauu show, just it cant work normal(first and last vertex hvnt move to middle), btw, ur this script not bad too, thanks for sharing!

http://www.scriptspot.com/3ds-max/scripts/turboreverse
this script for turbosmooth reverse to previous poly

i looking for script reverse poly to previous spline, attachment got show(No1 already become No2, can reverse back to No1?), is it possible?

It is possible, try the attached script.
It will only work if your editable poly was first a renderable spline.
It doesn't work with editable mesh or edit_poly modifier.

Select your editable poly and execute the script. (I just tested it on max 2013)

hi LittleLordPotala,
are you have mail, i want to send you another solution for testing this kind of problem.

great, this script really work, but got some limitation like what u say, cant work with editable mesh or edit poly modifier, and if got more than one spline, it cant get the right result~

This is your function
You can set manually thickness and sides

fn polyToSpline obj thickness: sides: =
(
if selection.count == 1 and classof obj == Editable_Poly do
(
max create mode
with redraw off
(
edgesCount = obj.edges.count
polyOp.createShape obj #{1..edgesCount} smooth:false name:"PolySpline"
ps = $PolySpline ; ps.wirecolor = orange ; ps.thickness = thickness ; ps.sides = sides
ps.render_displayRenderMesh = ps.render_renderable = true ; updateshape ps ; ps.name = uniquename ps.name ; select ps
)
)
)
polyToSpline $ thickness:0.3 sides:12

thanks for reply, have try, but got some problem, first and last vertex wont at center..
attachment in 2010 format

Use this script:Spline in middle