def __init__(self, target = Vector(), radius, strength):
'''
Constructor
'''
self.delta = Vector()
self.target = target
self.strength = strength
self.setRadius(radius)
class Attraction(Behaviour):
'''
classdocs
'''
delta = Vector()
target = Vector()
radius = 0
radiusSq = 0
strength = 0
def __init__(self, target = Vector(), radius, strength):
'''
Constructor
'''
self.delta = Vector()
self.target = target
self.strength = strength
self.setRadius(radius)
def setRadius(self, radius):
self.radius = radius
self.radiusSq = radius * radius
def apply(self, p, dt, index):
#call base(s)
super(Attraction, self).apply(*args, **kw)
# Vector pointing from particle to target.
self.delta.copy(self.target).sub(p.pos)
# Squared distance to target.
distSq = self.delta.magSq()
# Limit force to behaviour radius.
if ( distSq < self.radiusSq and distSq > 0.000001):
# Calculate force vector.
self.delta.norm().scale(1.0 - distSq / self.radiusSq)
#Apply force.
p.acc.add (self.delta.scale(strength))
