IKFK Snapping

ikfk.py

import maya.cmds as mc
import maya.OpenMaya as om

ik_control = 'IK_ctl'
pv_control = 'PV_ctl'
ik_joints = ['001_ik', '002_ik', '003_ik']
fk_controls = ['001_ctl', '002_ctl', '003_ctl']
ik_attr = 'Settings_locShape.IkFk'

def get_rotation(transform):
    return mc.getAttr('{}.rotate'.format(transform))[0]

def set_rotation(transform, rotation):
    mc.setAttr('{}.rotate'.format(transform), *rotation)


def get_token():
    name = mc.ls(sl=True)[0]
    return name[0:6]
    
def ik2fk():
    token = get_token()
    for i, j in enumerate(fk_controls):
        rot = get_rotation(token + ik_joints[i])
        set_rotation(token + j, rot)
    mc.setAttr(token + ik_attr, 1)

def fk2ik():
    token = get_token()
    # Get the fk controls as points in space & convert to Vec
    p1 = mc.xform(token + fk_controls[0], ws=True, q=True, t=True)
    v1 = om.MVector(*p1)
    p2 = mc.xform(token + fk_controls[1], ws=True, q=True, t=True)
    v2 = om.MVector(*p2)
    p3 = mc.xform(token + fk_controls[2], ws=True, q=True, t=True)
    v3 = om.MVector(*p3)
    # Position the IK control on the FK wrist and rotate it
    ik_rot = mc.xform(token + fk_controls[2], ws=True, q=True, ro=True)
    mc.xform(token + ik_control, ws=True, t=p3, ro=ik_rot)
    
    # find an average between p1 and p3
    midpoint = (v3 + v1) / 2
    
    # get a direction vector
    pv_dir = v2 - midpoint
    
    # calculate the exact position
    pv_pos = (pv_dir * 3) + midpoint

    
    # position the Pole Vector on that extended point
    mc.xform(token + pv_control, ws=True, t=pv_pos)
    mc.setAttr(token + ik_attr, 0)


ik2fk()
fk2ik()