FFD Control Point to World Space and Back Again

[Anonymous]

I'm trying to convert FFD points from their custom space to world space and back again, but There is some error in the converting back portion. For some reason 0.83333 gets added to the coordinates. e.g. On control_point_1 it goes from ->

"Orig: "
"Point 1: "
"Final: "

The actual position of my object in world space doesn't matter, it always adds 0.83333 to the coordinate. Can anyone see what I'm doing wrong?

 fn GetRealWorldCoords obj ffd ffdPoint =
 (
 print ("Orig: " + ffdPoint as string)
 objTM = obj.objectTransform
 modTM = (getModContextTM obj ffd) * ffd.lattice_transform.value
 modBBMin = getModContextBBoxMin obj ffd
 modBBMax = getModContextBBoxMax obj ffd
 point1PosWorld = modBBMin + (ffdPoint * (modBBMax - modBBMin)) * (inverse modTM) * objTM
 return point1PosWorld
 )
 
 fn GetFFDCoords obj ffd worldPoint =
 (
 objTM = obj.objectTransform
 modTM = (getModContextTM obj ffd) * ffd.lattice_transform.value
 modBBMin = getModContextBBoxMin obj ffd
 modBBMax = getModContextBBoxMax obj ffd
 controlPointPos = (worldPoint - modBBMin) * (inverse objTM) / (modBBMax - modBBMin)
 print ("Final: " + controlPointPos as string)
 )

[Anonymous]

Persistence pays off I guess.

(
 -- This script converts from FFD space to world space and back again.
 -- Neil Marshall neil@eightlines.com 12/31/2011
 -- If you use this code please credit me.

 fn FFDSpaceToWorldSpace obj ffd controlPoint =
 (
 if classOf controlPoint != Point3 then
 (
 print "Error: You need to pass in a point 3 to properly convert a FFD to world space"
 return undefined
 )
 
 objTM = obj.objecttransform
 modTM = (getModContextTM obj ffd) * ffd.lattice_transform.value
 modBBMin = getModContextBBoxMin obj ffd
 modBBMax = getModContextBBoxMax obj ffd
 size = modBBMax - modBBMin
 thePoint = modBBMin * inverse ffd.lattice_transform.rotation + (controlPoint * size) * modTM * objTM
 return thePoint
 )
 
 fn WorldSpaceToFFDSpace obj ffd worldSpace =
 (
 objTM = obj.objecttransform
 modTM = (getModContextTM obj ffd) * ffd.lattice_transform.value
 modBBMin = getModContextBBoxMin obj ffd
 modBBMax = getModContextBBoxMax obj ffd
 size = modBBMax - modBBMin
 thePoint = (worldSpace * (inverse objTM) * (inverse modTM) - modBBMin) / size
 return thePoint
 )
 
 while $tester != undefined do
 (
 delete $tester
 )
 
 obj = $Box01
 animateAll obj.modifiers
 
 print ("Before FFD Space: " + obj.modifiers.control_point_3 as string)
 thePoint = FFDSpaceToWorldSpace obj obj.modifiers obj.modifiers.control_point_3
 
 if thePoint != undefined then
 (
 print ("WorldSpace: " + thePoint as string)
 point name:"tester" pos:thePoint
 obj.modifiers.control_point_3 = WorldSpaceToFFDSpace obj obj.modifiers thePoint
 print ("After FFD Space: " + obj.modifiers.control_point_3 as string)
 )
 
 ""
)