AActor::SetFakeNetPhysicsState

function Engine Since 5.1

#include "GameFramework/Actor.h"

Access: public

Description

Forces the physics body of this actor into a fake network-replicated sleep or wake state, used exclusively with EPhysicsReplicationMode::PredictiveInterpolation. Allows the replication system to hint the solver about the expected rest state.

Caveats & Gotchas

• The header comments explicitly state: "Limited for use with actors using EPhysicsReplicationMode::PredictiveInterpolation only." Calling this on actors using other replication modes has undefined behavior.
• This does not immediately update ReplicatedMovement.bRepPhysics — it operates at the physics body level. Changes here do not automatically propagate to clients via replication.
• If the physics body has constraints or joints, forcing a sleep state may not fully succeed if connected bodies are still active. Check the physics body's actual sleep state after calling this.

Signature

void SetFakeNetPhysicsState(bool bShouldSleep);

Parameters

Name	Type	Description	Default
bShouldSleep	bool	If true, force the physics body to sleep; if false, wake it.	—

Return Type

void

Example

Hinting the physics solver to sleep during interpolation C++

// Called by the physics replication system when predicting a rest state
void AMyPhysicsActor::ForceNetworkRestHint()
{
	// Only valid when using PredictiveInterpolation mode
	SetFakeNetPhysicsState(true); // Hint: we expect this body to be sleeping
}

Version History

Introduced in: 5.1

Version	Status	Notes
5.6	stable	—

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