Physics messages

Physics messages are sent between Physics or Physics2D bodies when their colliders interact.

Test whether messages are sent to your objects

Test that you receive a physics message by using a breakpoint or log.

Don't put breakpoints or logs after or inside other code when testing a method runs.

I am not receiving a message

I am receiving a message but no logic runs

You likely have an error in your logic. Common mistakes include:

Comparing tags using equality; use CompareTag to get proper warnings.
Destroying components instead of their gameObject, leading to the appearance that nothing happens.
Ignoring errors that throw exceptions, these cause the code after to not run (fix the exceptions to resolve the issue).

I am receiving a message twice

Both objects involved in a collision receive events. If you only want one to run, compare the instance IDs of the objects involved in the collision using GetInstanceID:

// Exit early if this instance ID is less than the other object involved in the collision. 
if (GetInstanceId() < collider.GetInstanceID())
    return;

Unity, huh, how?

Physics messages#

Test whether messages are sent to your objects#

I am not receiving a message#