Simulating Physics - Developing Games With Ruby - page 99

distance = Utils . distance_between(
obj . x, obj . y, object . x, object . y)
obj != object && distance < max_distance
end
end
end
Back to TankPhysics :
class TankPhysics < Component
# ...
def can_move_to? (x, y)
old_x, old_y = object . x, object . y
object . x = x
object . y = y
return false unless @map . can_move_to?(x, y)
@object_pool . nearby(object, 100 ) . each do | obj |
if collides_with_poly?(obj . box)
# Allow to get unstuck
old_distance = Utils . distance_between(
obj . x, obj . y, old_x, old_y)
new_distance = Utils . distance_between(
obj . x, obj . y, x, y)
return false if new_distance < old_distance
end
end
true
ensure
object . x = old_x
object . y = old_y
end
# ...
private
def collides_with_poly? (poly)
if poly
poly . each_slice( 2 ) do | x, y |
return true if Utils . point_in_poly(x, y, * box)
end
box . each_slice( 2 ) do | x, y |
return true if Utils . point_in_poly(x, y, * poly)
end
end
false
end