Collision
Collision callback payload for body-level listeners.
The engine reports a collision between two registered bodies. Bodies are identified by their registration keys from Modifier.physicsBody(key = ...).
Impulse and normal
impulse is a scalar magnitude representing the strength of the contact resolution for this event (engine-specific; typically proportional to momentum exchange).
(normalX, normalY) is the contact normal in world/container space as reported by the engine. In the current backend the normal points from this body toward the other body; conventions may differ across physics engines.
All numeric values are intended for UI feedback / effects (sound volume, haptics, particles) and should not be treated as strictly physically accurate across different engines or solver settings.
Parameters
Key of the body that owns the listener (the “this” body).
Key of the other body involved in the collision.
Contact impulse magnitude (engine-defined units).
X component of the reported collision normal.
Y component of the reported collision normal.