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fix recursive chain activations 'soft deadlock'

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This commit is contained in:
mischa 2024-04-04 00:52:23 +08:00
parent e2ab34a55e
commit 96af64f436
1 changed files with 37 additions and 3 deletions
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40
Assets/Mirror/Components/ForecastRigidbody/ForecastRigidbody.cs
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@ -48,6 +48,9 @@ public class ForecastRigidbody : NetworkBehaviour
[Header("Collision Chaining")]
[Tooltip("Enable to have actively predicted Rigidbodies activate other Rigidbodies they collide with.")]
public bool collisionChaining = true;
[Tooltip("If a player interacts with an object, it can recursively activate other objects it collides with.\nDepth is the chain link from A->B->C->etc., it doesn't mean the amount of A->B, A->C, etc.\nNeeds to be finite to avoid chain activations going on forever like A->B->C->A (easy to notice in the stacked prediction example.")]
public int maxCollisionChainingDepth = 2; // A->B->C is enough!
int remainingCollisionChainDepth;
// motion smoothing happen on-demand, because it requires moving physics components to another GameObject.
// this only starts at a given velocity and ends when stopped moving.
@ -102,8 +105,7 @@ public override void OnStartClient()
predictedRigidbody.isKinematic = true;
}
// client prediction API
public void AddPredictedForce(Vector3 force, ForceMode mode)
void AddPredictedForceInternal(Vector3 force, ForceMode mode)
{
// apply local force dampening.
// client applies a bit less force than the server, so that
@ -116,6 +118,26 @@ public void AddPredictedForce(Vector3 force, ForceMode mode)
predictedRigidbody.AddForce(force, mode);
}
// client prediction API
public void AddPredictedForce(Vector3 force, ForceMode mode)
{
// player interacted with this object explicitly.
// restart the collision chain at max.
remainingCollisionChainDepth = maxCollisionChainingDepth;
// add the predicted force
AddPredictedForceInternal(force, mode);
}
void AddPredictedForceChain(Vector3 force, ForceMode mode, int newChainDepth)
{
// apply the collision chain depth
remainingCollisionChainDepth = newChainDepth;
// add the predicted force
AddPredictedForceInternal(force, mode);
}
protected void BeginPredicting()
{
predictedRigidbody.isKinematic = false; // full physics sync
@ -144,6 +166,8 @@ protected void BeginFollowing()
predictedRigidbody.isKinematic = true; // full transform sync
state = ForecastState.FOLLOWING;
if (debugColors) rend.material.color = originalColor;
// reset the collision chain depth so it starts at 0 again next time
remainingCollisionChainDepth = 0;
OnBeginFollow();
// Debug.Log($"{name} BEGIN FOLLOW");
}
@ -317,6 +341,14 @@ void OnCollisionEnter(Collision collision)
// is the other object already predicting? then don't call events again.
if (other.state != ForecastState.FOLLOWING) return;
// collided with an object that has not yet been activate.
// should this object still activate other objects?
// for example, chain depth = 3 means: A->B->C.
// so C->D would not activate anymore.
// (we always need to check this only for inactivate objects,
// otherwise A->B->A->B etc. would reduce the chain depth forever).
if (remainingCollisionChainDepth <= 0) return;
// the other object is in FOLLOWING mode (kinematic).
// PhysX will register the collision, but not add the collision force while kinematic.
// we need to add the force manually, which will also begin predicting it.
@ -324,7 +356,9 @@ void OnCollisionEnter(Collision collision)
// => we need to calculate the direction manually to always be A->B.
Vector3 direction = other.transform.position - transform.position;
Vector3 impulse = direction.normalized * collision.impulse.magnitude;
other.AddPredictedForce(impulse, ForceMode.Impulse);
other.AddPredictedForceChain(impulse, ForceMode.Impulse, remainingCollisionChainDepth - 1);
}
// optional user callbacks, in case people need to know about events.