Pymunk change color of the shape on collision

Question

I am using pymunk for my pinball game. I am using four circle shapes, three as a bumper and one as a ball.

I need to change color of the shape that has collided with the ball.

bumper code :

for p in [(230, 100), (370, 100),(300,140)]:
    body = pymunk.Body(body_type=pymunk.Body.KINEMATIC)
    body.position = p
    shape2 = pymunk.Circle(body, 20)
    shape2.elasticity = 1.5
    shape2.collision_type = 3
    shape2.color = (31, 163, 5, 255)
    space.add(body, shape2)

ball code :

    global ballbody,shape1
    mass = 1
    radius = 14
    inertia = pymunk.moment_for_circle(mass, 0, radius, (0, 0))
    ballbody = pymunk.Body(mass, inertia)
    ballbody.position = 500,460
    shape1 = pymunk.Circle(ballbody, radius, (0, 0))
    shape1.elasticity = 0.96
    shape1.collision_type = 0
    space.add(ballbody, shape1)
    balls.append(shape1)

What I have tried is to change color of the shape on collision by adding a collision handler.

def bounceOnBumpers(space, arbiter,dummy):
    shape2.color = (0, 255, 0, 255)

h = space.add_collision_handler(COLLTYPE_BALL, COLLTYPE_GOAL)
h.begin = bounceOnBumpers

But it doesn't work, Only one bumper's color is changed.

And is there anyway to get names of the shapes that are collided ?

Answer 1

The second argument in the collision handler callback is the arbiter. The pymunk.Arbiter object encapsulates a pair of colliding shapes. With shapes property you can get the shapes in the order that they were defined in the collision handler:

def bounceOnBumpers(space, arbiter, dummy):
    shapes = arbiter.shapes
    shapes[0].color = (0, 255, 0, 255)
    shapes[1].color = (0, 255, 0, 255)