Instantaneous Input functions (GetKeyDown, GetMouseButtonDown, and others) will trigger inconsistently when used in FixedUpdate or any physics message function like OnCollisionEnter.
Physics is run at a fixed rate, with physics sometimes updating multiple times a frame or not at all. If input occurs on a frame where FixedUpdate isn't run, it won't be processed by your code.
See FixedUpdate for more information.
Cache values in Update, and consume them in FixedUpdate.
Unity, huh, how?
private bool _jump;
void Update()
{
// If jump wasn't consumed we stay true, even when jump wasn't pressed this frame.
_jump |= Input.GetKeyDown(KeyCode.Space);
}
void FixedUpdate()
{
if (_jump)
{
rigidbody.AddForce(_jumpForce, ForceMode.Impulse);
// Consume the jump input:
_jump = false;
}
}When using physics callbacks and not calling physics functions, you may be able to move your logic to Update.
private bool _triggerIsOccupied;
void Update()
{
if (!_triggerIsOccupied)
{
// Exit early, trigger is not occupied.
return;
}
// Handle input in Update:
if (Input.GetKeyDown(KeyCode.Space))
{
Example();
}
}
/* Keep track of whether the trigger is occupied: */
void OnTriggerEnter(Collider other)
{
_triggerIsOccupied = true;
}
void OnTriggerExit(Collider other)
{
_triggerIsOccupied = false;
}If you expect overlapping triggers, you can use a counter instead of a boolean.