maya PythonのOpenMaya の Vector で任意の座標からもっとも近い線分上の点を求める

# -*- coding: utf-8 -*-
import maya.cmds as cmds
from maya import OpenMaya
#任意の1点と線分の両端の座標から線分上のもっとも近い点を返す
def xGetClosestPoint(myPoint, begin, end):
    myVector3D = OpenMaya.MVector(myPoint[0] - begin[0], myPoint[1] - begin[1], myPoint[2] - begin[2])
    baseVector3D = OpenMaya.MVector(end[0] - begin[0], end[1] - begin[1], end[2] - begin[2])
    nDotProduct = myVector3D * baseVector3D
    print("nDotProduct= "+str(nDotProduct))
    if (nDotProduct > 0):
        print("Big if")
        nBaseLength = baseVector3D.length()
        print("nBaseLength= "+str(nBaseLength))
        nProjection = nDotProduct / nBaseLength
        
        if (nProjection < nBaseLength):
            print("small if")
            scaleValue = nProjection / nBaseLength
            print("scaleValue= "+str(scaleValue))
            baseVector3D = baseVector3D * scaleValue
            
            return [begin[0] + baseVector3D[0], begin[1] + baseVector3D[1], begin[2] + baseVector3D[2]]
        else:
            print("small else")
            return end

    else:
        print("Big else")
        return begin;
    

sel = cmds.ls(sl =True)

# get Translate
start = cmds.xform(sel[0],q=1 ,ws =True,t=True)
mid = cmds.xform(sel[1],q=1 ,ws =True,t=True)
end = cmds.xform(sel[2],q=1 ,ws =True,t=True)

# Vector for Translate
#startV = OpenMaya.MVector(start[0] ,start[1],start[2])
#midV = OpenMaya.MVector(mid[0] ,mid[1],mid[2])
#midV = OpenMaya.MVector(end[0] ,end[1],end[2])

c_vPos = xGetClosestPoint(mid, start, end)
cmds.xform("pSphere1",ws =True,translation=(c_vPos[0], c_vPos[1], c_vPos[2]) )