op dpad psuedocode

control.py

# magic numbers
scalePad = 1.5
dragAfterDistance = 60
recenterDelay = 1.2
velocityMultiplier = 9
cornerBuffer = 50

# scheduled method
def step(deltaTime):
	timeSinceRecenter = timeSinceRecenter + deltaTime

def onTouchBegan:
	if touch in lower left quadrant:
		# leave the dpad in place when the finger comes off briefly
		if timeSinceRecenter > recenterDelay:
			centerPoint = keepAwayFromEdges(touchLocation)
			timeSinceRecenter = 0

def onTouchMoved:
	if touch in lower left quadrant:
		timeSinceRecenter = 0
		delta = location - centerPoint
		if iPad:
			delta = delta * scalePad
		player.velocity = delta * velocityMultiplier
		# if the touch drifts, move the dpad
		distance_from_center = distance(location, centerPoint)
		if distance_from_center > dragAfterDistance:
			centerPoint = location + ((centerPoint-location) * (dragAfterDistance/distance_from_center))

# don't start with the dpad in the corner
def keepAwayFromEdges(touchLocation):
	return {x:MAX(cornerBuffer, touchLocation.x), y:MAX(cornerBuffer, touchLocation.y)}