# Demon Project - Compensate Null Script
# By Peter Agg
# peter.agg@googlemail.com / peteragg.co.uk
"""
This script is designed to compliment with my Enveloping Nulls Script.

The user is prompted to select a null which has already been Pose constrained to a bone.
It will then compensate the constraint by the length of the bone that it has been constrained to.
This is useful for _env nulls on IK chains, where the bone might be facing the opposite way. 

Note: As this is designed to go with the Enveloping Nulls Script it presumes that the null will only
have a single Pose constraint on it
"""

from win32com.client import constants as c

def Picknull():
	global Picked
	# Pick the model to work with
	Picked = Application.PickElement(c.siNullFilter, "Pick model", "Pick model" )
	# Right-Click bomb out
	if Picked[0] == 0:
		Application.logmessage("ERROR: Right button clicked, returning")
		return
	else:
		GetNullRef()
		
def GetNullRef():
	global PickedRef
	# get the  Bone which the _env null is constrained to
	constraints = Picked(2).Kinematics.Constraints			
	for k in constraints:
		# Make sure that the constraint is a Pose
		if str(k.Type) == "posecns":
			for l in k.constraining:		
				PickedRef = l
				Ref = PickedRef
			#"# Application.logmessage(str(Picked(2)) + " is constrained by a " + k.Type + " to: " + str(PickedRef))
			CompNull()


def CompNull():
	Application.logmessage(PickedRef)
	# Get it's length
	RefLength = Application.GetValue(str(PickedRef) + ".bone.length")
	#"# Application.logmessage("RefLength = " + str(RefLength))

	# Compensate the constraint by the bone length
	Application.SetValue(str(Picked(2)) + ".kine.posecns.posx", RefLength, "")
	
	
Picknull()