def do_step():
# Buffer all the move_by calls and do at once.
# Note that this does not buffer other state changes made in objects,
# such as a teleport - we really should have that facility for a proper
# simulation of a time step
# we should also enforce the restriction on the move limit for each
# type of object. At the moment, you can get around this limit by calling
# move_by in the compute_next_move method!
moves = [ ]
# give the defenders a chance to tell the normals what to do
# and try to teleport any zombies
for p in Defender.get_all_present_instances():
moves.append( (p,) + p.compute_next_move() )
# then give the normals a chance
for p in Normal.get_all_present_instances():
moves.append( (p,) + p.compute_next_move() )
# and finally the zombies, which may have been teleported to new positions
for p in Zombie.get_all_present_instances():
moves.append( (p,) + p.compute_next_move() )
# then execute the moves, even though other state may have been changed
# earlier
for (p, delta_x, delta_y) in moves:
p.move_by(delta_x, delta_y)
# then convert normals into zombies if the zombies are close enough
# Warning: z - number of zombies, n - number of normals, then the
# time complexity of this is O( z n )
for z in Zombie.get_all_present_instances():
for n in Normal.get_all_present_instances():
d_e_e = z.distances_to(n)[3]
d_touch = z.get_touching_threshold()
# print(z.get_name(), n.get_name(), d_e_e, d_touch)
if d_e_e <= d_touch:
x = n.get_xpos()
y = n.get_ypos()
new_z = Zombie(size=n.get_size(), haircolor='green',
xpos = x, ypos = y, move_limit=person_move_limit)
new_z.arrive()
n.leave()
Person.del_instance(n)
