OnTriggerEnter before FixedUpdate

This is a rather simple question but I just want to make absolutely sure. According to the docs, FixedUpdate is called immediately before the physics calculations. Does this include OnTriggerEnter?

So if I want to check the results of triggered collision, I can enable my collider, wait one frame in the FixedUpdate method, and then by the second time FixedUpdate is fired, I can safely assume that OnTriggerEnter would have already been called if a collision was registered, correct?

It seems to be working. After some testing I have yet to experience a time where OnTriggerEnter did not have the opportunity to fire before the second FixedUpdate, but I just want to be sure this is a reliable approach. Thank you!

 

I don't really know, but this is easy to check. Print Time.fixedTime in both FixedUpdate and OnTriggerEnter. Time.fixedTime is the current time of the physics engine, and is the same throughout the entire fixed frame.

So you'll get the same fixedTime in a FixedUpdate and a OnTriggerEnter. If you get that time first in FixedUpdate, that happens first. If you get the same in OnTriggerEnter, that happens first.

 

Thanks for the reply! I've already tested it and the order is exactly as I was expecting. My question is can I assume the order will always remain this way? Or is there some sort of multithreaded process in the background that can behave differently in different circumstances?

 

No, all of the engine code is single-threaded, and the order of the messages should be constant.

so, yes, you should be able to rely on the order.

 

Great! Thank you!