def generate(self, width, height, density, seed=None):
"""
Setup this galaxy with the correct width, height and generate the new planets.
"""
self.width = width
self.height = height
maxPlanets = (self.width-2) * (self.height-2) * density
prng = random.Random(seed)
while len(self.planets) < maxPlanets:
x = prng.randint(1, self.width-1)
y = prng.randint(1, self.height-1)
if (x,y) not in self.planets:
newPlanet = Planet(x,y)
newPlanet.generate(prng)
self.planets[(x,y)] = newPlanet
return
