AddForce in Update

Questions & Answers
1

I want to add force during an animation clip (using OnStateUpdate which is the same as Update).

So, the question is: how to AddForce in the Update method properly as if it was the FixedUpdate?

2

If you want to ensure that you’re reliably applying your physics forces during FixedUpdate() while simultaneously basing it on an animation that plays during Update(), you could use a Queue<> (or List<>, on the same general basis).

In short, you add forces to be applied during the animation, then “play them back” during the next FixedUpdate().

Queue<Vector3> qForces = new Queue<Vector3>();

// Simplified example call
void OnStateUpdate(/*etc.*/)
{
	// etc.
	qForces.Enqueue([FORCE_TO_APPLY]);
	// etc.
}

void FixedUpdate()
{
	if(qForces.Count > 0) // Only worry about this when the queue isn't empty
	{
		Vector3 combinedForce = Vector3.zero;
		while(qForces.Count > 0)
		{
			combinedForce += qForces.Dequeue();
		}
		// Make only a single Rigidbody.AddForce() call using the
		// sum of all forces gathered between physics passes
		rb.AddForce(combinedForce, ForceMode.[Impulse/VelocityChange/etc.]);
	}
}

Edit: Efficiency improvement