def physicsStep(self, entity):
force = Vector()
if not isinstance(self.root, Sprite):
stack = [self.root]
while len(stack) > 0:
curr = stack.pop()
d = curr.size/Vector.Distance(curr.center_of_mass, entity.pos)
if d < THETA:
force += QuadTree.calc_force(curr.center_of_mass,
entity.pos,
curr.total_mass,
entity.mass)
else:
for c in curr.children.values():
if c is None or c is entity:
continue
elif isinstance(c, Sprite):
force += QuadTree.calc_force(c.pos, entity.pos,
c.mass, entity.mass)
else:
stack.append(c)
entity.pos = entity.pos + entity.vel * DT
entity.vel = entity.vel + (force / entity.mass) * DT
if Vector.Length(entity.vel) > SPEED_LIMIT:
entity.vel *= OVERSPEED_DAMP
else:
entity.vel *= NORMAL_DAMP
def calc_force(pos1, pos2, mass1, mass2):
force = (pos1 - pos2) / Vector.Distance(pos1, pos2)**3
force *= mass1*mass2 * G
return force
def BruteForceCircles(self, group):
for a, b in combinations(group, 2):
collided = Vector.Distance(a.pos, b.pos) < (a.rad + b.rad)
if collided:
physics.collide(a, b)