Is "SetAllBodiesSimulatePhysics()" broken in UE5.5.1?

Development Programming & Scripting C++
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1

For a few days I have been experiencing an inexplicable teleportation in my skeletal mesh.

I find out this function is responsible.
SetAllBodiesSimulatePhysics(true);

When this function is executed my skeletal mesh is teleported to the place where the pawn was spawned (The PlayerStart Location).

This did not happen to me in any of the previous versions to UE5.5.1

I really don’t know if it’s the version that’s to blame for this.
I’ve really been trying to do some skeletal mesh optimization these past few days…

	bEnableUpdateRateOptimizations = true; 
	bComponentUseFixedSkelBounds = true; 
	bDisplayDebugUpdateRateOptimizations = false; 


	bUseScreenRenderStateForUpdate = true; 
	bReplicatePhysicsToAutonomousProxy = true;
	bRenderStatic = false; 
	bUseAttachParentBound = true;
	bSkipBoundsUpdateWhenInterpolating = true;
	bSkipKinematicUpdateWhenInterpolating = true;
	bNoSkeletonUpdate = false;
	bPauseAnims = false;
	//bDisableRigidBodyAnimNode=true;
	KinematicBonesUpdateType = EKinematicBonesUpdateToPhysics::Type::SkipAllBones;	
	//MeshComponentUpdate::OnlyUpdateWhenRendered;


	AnimUpdateRateParams->bShouldUseLodMap = true;
	AnimUpdateRateParams->BaseNonRenderedUpdateRate = 4;
	AnimUpdateRateParams->LODToFrameSkipMap.Add(0,0); //[LOD, FPS]
	AnimUpdateRateParams->LODToFrameSkipMap.Add(1,1);
	AnimUpdateRateParams->LODToFrameSkipMap.Add(2,2);
	AnimUpdateRateParams->LODToFrameSkipMap.Add(3,3);
	AnimUpdateRateParams->LODToFrameSkipMap.Add(4,4);
	AnimUpdateRateParams->MaxEvalRateForInterpolation = 10;
	AnimUpdateRateParams->BaseNonRenderedUpdateRate = 6;

	VisibilityBasedAnimTickOption = EVisibilityBasedAnimTickOption::AlwaysTickPoseAndRefreshBones;

But I have /* commented */ them and I am still experiencing the problem.

My ragdoll code is the same since UE4.27 version

void UCharacterSkeletalMehs::RagDoll() 
{	
	SetGenerateOverlapEvents(false);
	CanCharacterStepUpOn = ECanBeCharacterBase::ECB_Yes;
	SetCollisionEnabled( ECollisionEnabled::PhysicsOnly );	
	SetCollisionObjectType( ECollisionChannel::ECC_Pawn );
	SetCollisionResponseToAllChannels(ECollisionResponse::ECR_Ignore);
	SetCollisionResponseToChannel( ECollisionChannel::ECC_WorldStatic, ECollisionResponse::ECR_Block);

	// Enable ragdoll physics
	SetAllBodiesSimulatePhysics(true);
	SetSimulatePhysics(true);
	WakeAllRigidBodies();
	bBlendPhysics = true;	
}

Does this happen to anyone else?

Because if I know it’s a problem with the UE5.5.1 version then I stop looking for bugs in my code and wait for the U5.5.2 version.

Otherwise I’ll keep looking for bugs in my code.

Thank you very much for the help!!

2

Ok… I tried the new code on UE4.4 version and I have the same problem.

And with the old code in UE4.4 version there is not problem.

So the problem must be something in the configuration I’ve done this last month
(I created a bug in my new code… Trying to optimize I broke everything…).

Does anyone know what configuration option could be causing this problem?

Thank you so much!!

3

I finally found the problem:

This was causing the problem:
KinematicBonesUpdateType = EKinematicBonesUpdateToPhysics::Type::SkipAllBones;

This solved the problem:
KinematicBonesUpdateType = EKinematicBonesUpdateToPhysics::Type::SkipSimulatingBones;

I don’t understand how commenting these options in the constructor didn’t work.
I had to test all the options one by one from the blueprint.

It’s the price you pay for optimization.
On one hand you gain FPS and on the other you lose super cool things.

Well, I need the skeletal mesh ragdoll in the same place where the pawn dies.
This optimization is not useful for me then. Bad luck.