Updating a Postprocessing effect

[MissingAFew]

I'd like to be able to modify and update a postprocessing effect in a loop for a particular effect. Specifically, I'm wanting to modify BulgeAmount such that it loops and interpolates between -0.5 and 0.5:

effect = BulgeEffect(BulgeAmount)
vizfx.postprocess.addEffect(effect)

I tried using the director function to create a new thread and have it loop separately from the main thread but it crashed. This is the code I tried:

import viz
import viztask

import vizfx.postprocess
from vizfx.postprocess.distort import PincushionEffect

def UpdateDrunkEffect():
	DrunkValue = 0
	Modulate = True
	
	Length = 60
	
	while True:
		if DrunkValue <= 0:
			Modulate = True
				
		if DrunkValue >= 1:
			Modulate = False
			Length -= 1
				
		if Modulate:
			DrunkValue += .01
		else:
			DrunkValue -= .01
	
		effect = PincushionEffect(DrunkValue)
		vizfx.postprocess.addEffect(effect)
		
		if Length == 0:
			effect = PincushionEffect(0)
			vizfx.postprocess.addEffect(effect)
			break
		
viz.director( UpdateDrunkEffect )

Is there a better way to do this that I'm just not thinking of? How can I go about changing the postprocessing effect in a loop without it freezing the application?

[Jeff]

Here's an example that uses the viztask.waitCall command to call effect.setBulge and waits until the vizact.mix parameters are complete.

import viz
import vizact
import viztask

viz.go()
viz.addChild('gallery.osgb')

import vizfx.postprocess
from vizfx.postprocess.distort import BulgeEffect
effect = BulgeEffect(0,radius=1)
vizfx.postprocess.addEffect(effect)

def BulgeTask():
	
	increase = vizact.mix(-0.5,0.5,time=2)
	decrease = vizact.mix(0.5,-0.5,time=2)

	while True:

		yield viztask.waitCall(effect.setBulge,increase)
		yield viztask.waitCall(effect.setBulge,decrease)

viztask.schedule( BulgeTask() )

[MissingAFew]

Thank you Jeff! This is exactly what I was trying to do. You make my life easy.