Brute force method to adjust the poleVector of one ik chain to line up the elbow joint of a similar arm chain

adjust_pv_to_elbow.py

'''
Brute force method to adjust the poleVector of one ik chain
to line up the elbow joint of a similar arm chain
'''

import pymel.core as pymel
import maya.OpenMaya as OpenMaya

def adjust_pv_to_elbow(poleVector, ik_elbow, elbow):
    """
    Move the poleVector of an ik chain until the elbow joint of that
    ik chain, lines up in worldspace to the target elbow worldspace position

    *Arguments:*
    	* ``poleVector`` 
        * ``ik_elbow`` elbow joint driven by the poleVector
        * ``elbow``    elbow joint we are trying to get the ik_elbow positioned at
        

    *Keyword Arguments:*
    	* ``None``

    *Returns:*
    	* ``None``

    *Author:*
    * randall.hess
    """    
    
    pymel.select(poleVector, r=True)
    
    # this is the base elbow joint target
    elbow_pos = pymel.xform(elbow, ws=1, q=1, t=1)    
    elbow_vec = OpenMaya.MVector(elbow_pos[0], elbow_pos[1], elbow_pos[2])
    
    # if we get this close we are probably good
    tolerance = 0.00001
    
    # iterate the poleVector moving to decrease the distance between the two elbow joints
    for index in range(0, 100):
        
          # this is the elbow joint that will move when the pv is adjusted
        ik_elbow_pos = pymel.xform(ik_elbow, ws=1, q=1, t=1)
        ik_elbow_vec = OpenMaya.MVector(ik_elbow_pos[0], ik_elbow_pos[1], ik_elbow_pos[2])
        length = OpenMaya.MVector(ik_elbow_vec - elbow_vec).length()
    
        # go through each component and subtract		
        diff_x = ik_elbow_pos[0] - elbow_pos[0]
        diff_y = ik_elbow_pos[1] - elbow_pos[1]
        diff_z = ik_elbow_pos[2] - elbow_pos[2]
    
        # move the poleVector		
        if length == 0:
            break
        elif length < tolerance:
            print 'length is under the tolerance!'
            break
        
        if length > 0:			
            pymel.move(-diff_x, -diff_y, -diff_z, ws=True, wd=True, r=True)			
        else:
            pymel.move(diff_x, diff_y, diff_z, ws=True, wd=True,r=True)