UnrealEngineUWP/Engine/Source/Runtime/AnimGraphRuntime/Private/BoneControllers/AnimNode_AnimDynamics.cpp

// Copyright 1998-2016 Epic Games, Inc. All Rights Reserved.

#include "AnimGraphRuntimePrivatePCH.h"
#include "AnimNode_AnimDynamics.h"
#include "Animation/AnimInstanceProxy.h"

DEFINE_STAT(STAT_AnimDynamicsOverall);
DEFINE_STAT(STAT_AnimDynamicsWindData);
DEFINE_STAT(STAT_AnimDynamicsBoneEval);
DEFINE_STAT(STAT_AnimDynamicsSubSteps);

TAutoConsoleVariable<int32> CVarRestrictLod(TEXT("p.AnimDynamicsRestrictLOD"), -1, TEXT("Forces anim dynamics to be enabled for only a specified LOD, -1 to enable on all LODs."));
TAutoConsoleVariable<int32> CVarEnableDynamics(TEXT("p.AnimDynamics"), 1, TEXT("Enables/Disables anim dynamics node updates."));
TAutoConsoleVariable<int32> CVarEnableAdaptiveSubstep(TEXT("p.AnimDynamicsAdaptiveSubstep"), 0, TEXT("Enables/disables adaptive substepping. Adaptive substepping will substep the simulation when it is necessary and maintain a debt buffer for time, always trying to utilise as much time as possible."));
TAutoConsoleVariable<int32> CVarAdaptiveSubstepNumDebtFrames(TEXT("p.AnimDynamicsNumDebtFrames"), 5, TEXT("Number of frames to maintain as time debt when using adaptive substepping, this should be at least 1 or the time debt will never be cleared."));
TAutoConsoleVariable<int32> CVarEnableWind(TEXT("p.AnimDynamicsWind"), 1, TEXT("Enables/Disables anim dynamics wind forces globally."));

const float FAnimNode_AnimDynamics::MaxTimeDebt = (1.0f / 60.0f) * 5.0f; // 5 frames max debt

FAnimNode_AnimDynamics::FAnimNode_AnimDynamics()
: BoxExtents(0.0f)
, LocalJointOffset(0.0f)
, GravityScale(1.0f)
, bLinearSpring(false)
, bAngularSpring(false)
, LinearSpringConstant(0.0f)
, AngularSpringConstant(0.0f)
, bEnableWind(true)
, WindScale(1.0f)
, bOverrideLinearDamping(false)
, LinearDampingOverride(0.0f)
, bOverrideAngularDamping(false)
, AngularDampingOverride(0.0f)
, bDoUpdate(true)
, bDoEval(true)
, NumSolverIterationsPreUpdate(4)
, NumSolverIterationsPostUpdate(1)
, bUsePlanarLimit(true)
{

}

void FAnimNode_AnimDynamics::Initialize(const FAnimationInitializeContext& Context)
{
	FAnimNode_SkeletalControlBase::Initialize(Context);

	FBoneContainer& RequiredBones = Context.AnimInstanceProxy->GetRequiredBones();

	BoundBone.Initialize(RequiredBones);

	if (bChain)
	{
		ChainEnd.Initialize(RequiredBones);
	}

	for(FAnimPhysPlanarLimit& PlanarLimit : PlanarLimits)
	{
		PlanarLimit.DrivingBone.Initialize(RequiredBones);
	}

	if(BoundBone.IsValid(RequiredBones))
	{
		RequestInitialise();
	}

	NextTimeStep = 0.0f;
	TimeDebt = 0.0f;
}

void FAnimNode_AnimDynamics::UpdateInternal(const FAnimationUpdateContext& Context)
{
	FAnimNode_SkeletalControlBase::UpdateInternal(Context);

	NextTimeStep = Context.GetDeltaTime();
}

void FAnimNode_AnimDynamics::EvaluateBoneTransforms(USkeletalMeshComponent* SkelComp, FCSPose<FCompactPose>& MeshBases, TArray<FBoneTransform>& OutBoneTransforms)
{
	SCOPE_CYCLE_COUNTER(STAT_AnimDynamicsOverall);

	int32 RestrictToLOD = CVarRestrictLod.GetValueOnAnyThread();
	bool bEnabledForLod = RestrictToLOD >= 0 ? SkelComp->PredictedLODLevel == RestrictToLOD : true;

	if (CVarEnableDynamics.GetValueOnAnyThread() == 1 && bEnabledForLod)
	{
		// Pretty nasty - but there isn't really a good way to get clean bone transforms (without the modification from
		// previous runs) so we have to initialize here, checking often so we can restart a simulation in the editor.
		if (bRequiresInit)
		{
			InitPhysics(SkelComp, MeshBases);
			bRequiresInit = false;
		}

		if (bDoUpdate && NextTimeStep > 0.0f)
		{
			// Wind / Force update
			if(CVarEnableWind.GetValueOnAnyThread() == 1 && bEnableWind)
			{
				SCOPE_CYCLE_COUNTER(STAT_AnimDynamicsWindData);

				for(FAnimPhysRigidBody* Body : BaseBodyPtrs)
				{
					if(SkelComp && SkelComp->GetWorld())
					{
						Body->bWindEnabled = bEnableWind;

						if(Body->bWindEnabled)
						{
							UWorld* World = SkelComp->GetWorld();
							FSceneInterface* Scene = World->Scene;

							// Unused by our simulation but needed for the call to GetWindParameters below
							float WindMinGust;
							float WindMaxGust;

							// Setup wind data
							Body->bWindEnabled = true;
							Scene->GetWindParameters(SkelComp->ComponentToWorld.TransformPosition(Body->Pose.Position), Body->WindData.WindDirection, Body->WindData.WindSpeed, WindMinGust, WindMaxGust);

							Body->WindData.WindDirection = SkelComp->ComponentToWorld.Inverse().TransformVector(Body->WindData.WindDirection);
							Body->WindData.WindAdaption = FMath::FRandRange(0.0f, 2.0f);
							Body->WindData.BodyWindScale = WindScale;
						}
					}
				}
			}
			else
			{
				SCOPE_CYCLE_COUNTER(STAT_AnimDynamicsWindData);
				// Disable wind.
				for(FAnimPhysRigidBody* Body : BaseBodyPtrs)
				{
					Body->bWindEnabled = false;
				}
			}

			if (CVarEnableAdaptiveSubstep.GetValueOnAnyThread() == 1)
			{
				float FixedTimeStep = MaxSubstepDeltaTime * CurrentTimeDilation;

				// Clamp the fixed timestep down to max physics tick time.
				// at high speeds the simulation will not converge as the delta time is too high, this will
				// help to keep constraints together at a cost of physical accuracy
				FixedTimeStep = FMath::Clamp(FixedTimeStep, 0.0f, MaxPhysicsDeltaTime);

				// Calculate number of substeps we should do.
				int32 NumIters = FMath::TruncToInt((NextTimeStep + (TimeDebt * CurrentTimeDilation)) / FixedTimeStep);
				NumIters = FMath::Clamp(NumIters, 0, MaxSubsteps);

				SET_DWORD_STAT(STAT_AnimDynamicsSubSteps, NumIters);

				// Store the remaining time as debt for later frames
				TimeDebt = (NextTimeStep + TimeDebt) - (NumIters * FixedTimeStep);
				TimeDebt = FMath::Clamp(TimeDebt, 0.0f, MaxTimeDebt);

				NextTimeStep = FixedTimeStep;

				for (int32 Iter = 0; Iter < NumIters; ++Iter)
				{
					UpdateLimits(SkelComp, MeshBases);
					FAnimPhys::PhysicsUpdate(FixedTimeStep, BaseBodyPtrs, LinearLimits, AngularLimits, Springs, NumSolverIterationsPreUpdate, NumSolverIterationsPostUpdate);
				}
			}
			else
			{
				// Do variable frame-time update
				const float MaxDeltaTime = MaxPhysicsDeltaTime;

				NextTimeStep = FMath::Min(NextTimeStep, MaxDeltaTime);

				UpdateLimits(SkelComp, MeshBases);
				FAnimPhys::PhysicsUpdate(NextTimeStep, BaseBodyPtrs, LinearLimits, AngularLimits, Springs, NumSolverIterationsPreUpdate, NumSolverIterationsPostUpdate);
			}
		}

		if (bDoEval)
		{
			SCOPE_CYCLE_COUNTER(STAT_AnimDynamicsBoneEval);

			const FBoneContainer& BoneContainer = MeshBases.GetPose().GetBoneContainer();

			for (int32 Idx = 0; Idx < BoundBoneReferences.Num(); ++Idx)
			{
				FBoneReference& CurrentChainBone = BoundBoneReferences[Idx];
				FAnimPhysRigidBody& CurrentBody = Bodies[Idx].RigidBody.PhysBody;

				// Skip invalid bones
				if(!CurrentChainBone.IsValid(BoneContainer))
				{
					continue;
				}

				FCompactPoseBoneIndex BoneIndex = CurrentChainBone.GetCompactPoseIndex(BoneContainer);

				FTransform NewBoneTransform(CurrentBody.Pose.Orientation, CurrentBody.Pose.Position + CurrentBody.Pose.Orientation.RotateVector(JointOffsets[Idx]));
				OutBoneTransforms.Add(FBoneTransform(BoneIndex, NewBoneTransform));
			}
		}
	}
}

void FAnimNode_AnimDynamics::InitializeBoneReferences(const FBoneContainer& RequiredBones)
{
	BoundBone.Initialize(RequiredBones);

	if(bChain)
	{
		ChainEnd.Initialize(RequiredBones);
	}
	
	for(FBoneReference& BoneRef : BoundBoneReferences)
	{
		BoneRef.Initialize(RequiredBones);
	}
}

void FAnimNode_AnimDynamics::GatherDebugData(FNodeDebugData& DebugData)
{
	const float ActualAlpha = AlphaScaleBias.ApplyTo(Alpha);

	FString DebugLine = DebugData.GetNodeName(this);
	DebugLine += FString::Printf(TEXT("(Alpha: %.1f%%)"), ActualAlpha*100.f);

	DebugData.AddDebugItem(DebugLine);
	ComponentPose.GatherDebugData(DebugData.BranchFlow(1.f));
}

bool FAnimNode_AnimDynamics::IsValidToEvaluate(const USkeleton* Skeleton, const FBoneContainer& RequiredBones)
{
	bool bValid = BoundBone.IsValid(RequiredBones);

	if (bChain)
	{
		bValid = bValid && ChainEnd.IsValid(RequiredBones);
	}

	return bValid;
}

int32 FAnimNode_AnimDynamics::GetNumBodies() const
{
	return Bodies.Num();
}

const FAnimPhysRigidBody& FAnimNode_AnimDynamics::GetPhysBody(int32 BodyIndex) const
{
	return Bodies[BodyIndex].RigidBody.PhysBody;
}

#if WITH_EDITOR
FVector FAnimNode_AnimDynamics::GetBodyLocalJointOffset(int32 BodyIndex) const
{
	if (JointOffsets.IsValidIndex(BodyIndex))
	{
		return JointOffsets[BodyIndex];
	}
	return FVector::ZeroVector;
}

int32 FAnimNode_AnimDynamics::GetNumBoundBones() const
{
	return BoundBoneReferences.Num();
}

const FBoneReference* FAnimNode_AnimDynamics::GetBoundBoneReference(int32 Index) const
{
	if(BoundBoneReferences.IsValidIndex(Index))
	{
		return &BoundBoneReferences[Index];
	}
	return nullptr;
}

#endif

void FAnimNode_AnimDynamics::InitPhysics(USkeletalMeshComponent* Component, FCSPose<FCompactPose>& MeshBases)
{
	// Clear up any existing physics data
	TermPhysics();

	const FBoneContainer& BoneContainer = MeshBases.GetPose().GetBoneContainer();

	
	// List of bone indices in the chain.
	TArray<int32> ChainBoneIndices;
	TArray<FName> ChainBoneNames;

	if(ChainEnd.IsValid(BoneContainer))
	{
		// Add the end of the chain. We have to walk from the bottom upwards to find a chain
		// as walking downwards doesn't guarantee a single end point.

		ChainBoneIndices.Add(ChainEnd.BoneIndex);
		ChainBoneNames.Add(ChainEnd.BoneName);

		int32 ParentBoneIndex = BoneContainer.GetParentBoneIndex(ChainEnd.BoneIndex);

		// Walk up the chain until we either find the top or hit the root bone
		while(ParentBoneIndex != 0)
		{
			ChainBoneIndices.Add(ParentBoneIndex);
			ChainBoneNames.Add(Component->GetBoneName(ParentBoneIndex));

			if(ParentBoneIndex == BoundBone.BoneIndex)
			{
				// Found the top of the chain
				break;
			}

			ParentBoneIndex = BoneContainer.GetParentBoneIndex(ParentBoneIndex);
		}

		// Bail if we can't find a chain, and let the user know
		if(ParentBoneIndex != BoundBone.BoneIndex)
		{
			UE_LOG(LogAnimation, Error, TEXT("AnimDynamics: Attempted to find bone chain starting at %s and ending at %s but failed."), *BoundBone.BoneName.ToString(), *ChainEnd.BoneName.ToString());
			return;
		}
	}
	else
	{
		// No chain specified, just use the bound bone
		ChainBoneIndices.Add(BoundBone.BoneIndex);
		ChainBoneNames.Add(BoundBone.BoneName);
	}

	Bodies.Reserve(ChainBoneIndices.Num());
	// Walk backwards here as the chain was discovered in reverse order
	for (int32 Idx = ChainBoneIndices.Num() - 1; Idx >= 0; --Idx)
	{
		TArray<FAnimPhysShape> BodyShapes;
		BodyShapes.Add(FAnimPhysShape::MakeBox(BoxExtents));

		FBoneReference LinkBoneRef;
		LinkBoneRef.BoneName = ChainBoneNames[Idx];
		LinkBoneRef.Initialize(BoneContainer);

		// Calculate joint offsets by looking at the length of the bones and extending the provided offset
		if (BoundBoneReferences.Num() > 0)
		{
			FTransform CurrentBoneTransform = MeshBases.GetComponentSpaceTransform(LinkBoneRef.GetCompactPoseIndex(BoneContainer));
			FTransform PreviousBoneTransform = MeshBases.GetComponentSpaceTransform(BoundBoneReferences.Last().GetCompactPoseIndex(BoneContainer));

			FVector PreviousAnchor = PreviousBoneTransform.TransformPosition(-LocalJointOffset);
			float DistanceToAnchor = (PreviousBoneTransform.GetTranslation() - CurrentBoneTransform.GetTranslation()).Size() * 0.5f;

			if(LocalJointOffset.SizeSquared() < SMALL_NUMBER)
			{
				// No offset, just use the position between chain links as the offset
				// This is likely to just look horrible, but at least the bodies will
				// be placed correctly and not stack up at the top of the chain.
				JointOffsets.Add(PreviousAnchor - CurrentBoneTransform.GetTranslation());
			}
			else
			{
				// Extend offset along chain.
				JointOffsets.Add(LocalJointOffset.GetSafeNormal() * DistanceToAnchor);
			}
		}
		else
		{
			// No chain to worry about, just use the specified offset.
			JointOffsets.Add(LocalJointOffset);
		}

		BoundBoneReferences.Add(LinkBoneRef);

		FTransform BodyTransform = MeshBases.GetComponentSpaceTransform(LinkBoneRef.GetCompactPoseIndex(BoneContainer));
		BodyTransform.SetTranslation(BodyTransform.GetTranslation() + BodyTransform.GetRotation().RotateVector(-LocalJointOffset));

		FAnimPhysLinkedBody NewChainBody(BodyShapes, BodyTransform.GetTranslation(), LinkBoneRef);
		FAnimPhysRigidBody& PhysicsBody = NewChainBody.RigidBody.PhysBody;
		PhysicsBody.Pose.Orientation = BodyTransform.GetRotation();
		PhysicsBody.PreviousOrientation = PhysicsBody.Pose.Orientation;
		PhysicsBody.NextOrientation = PhysicsBody.Pose.Orientation;
		PhysicsBody.CollisionType = CollisionType;

		switch(PhysicsBody.CollisionType)
		{
			case AnimPhysCollisionType::CustomSphere:
				PhysicsBody.SphereCollisionRadius = SphereCollisionRadius;
				break;
			case AnimPhysCollisionType::InnerSphere:
				PhysicsBody.SphereCollisionRadius = BoxExtents.GetAbsMin() / 2.0f;
				break;
			case AnimPhysCollisionType::OuterSphere:
				PhysicsBody.SphereCollisionRadius = BoxExtents.GetAbsMax() / 2.0f;
				break;
			default:
				break;
		}

		if (bOverrideLinearDamping)
		{
			PhysicsBody.bLinearDampingOverriden = true;
			PhysicsBody.LinearDamping = LinearDampingOverride;
		}

		if (bOverrideAngularDamping)
		{
			PhysicsBody.bAngularDampingOverriden = true;
			PhysicsBody.AngularDamping = AngularDampingOverride;
		}

		PhysicsBody.GravityScale = GravityScale;

		// Link to parent
		if (Bodies.Num() > 0)
		{
			NewChainBody.ParentBody = &Bodies.Last().RigidBody;
		}

		Bodies.Add(NewChainBody);
	}
	
	BaseBodyPtrs.Empty();
	for(FAnimPhysLinkedBody& Body : Bodies)
	{
		BaseBodyPtrs.Add(&Body.RigidBody.PhysBody);
	}

	// Set up transient constraint data
	const bool bXAxisLocked = ConstraintSetup.LinearXLimitType != AnimPhysLinearConstraintType::Free && ConstraintSetup.LinearAxesMin.X - ConstraintSetup.LinearAxesMax.X == 0.0f;
	const bool bYAxisLocked = ConstraintSetup.LinearYLimitType != AnimPhysLinearConstraintType::Free && ConstraintSetup.LinearAxesMin.Y - ConstraintSetup.LinearAxesMax.Y == 0.0f;
	const bool bZAxisLocked = ConstraintSetup.LinearZLimitType != AnimPhysLinearConstraintType::Free && ConstraintSetup.LinearAxesMin.Z - ConstraintSetup.LinearAxesMax.Z == 0.0f;

	ConstraintSetup.bLinearFullyLocked = bXAxisLocked && bYAxisLocked && bZAxisLocked;

	// Cache physics settings to avoid accessing UPhysicsSettings continuously
	if(UPhysicsSettings* Settings = UPhysicsSettings::Get())
	{
		MaxPhysicsDeltaTime = Settings->MaxPhysicsDeltaTime;
		MaxSubstepDeltaTime = Settings->MaxSubstepDeltaTime;
		MaxSubsteps = Settings->MaxSubsteps;
	}
	else
	{
		MaxPhysicsDeltaTime = (1.0f/30.0f);
		MaxSubstepDeltaTime = (1.0f/60.0f);
		MaxSubsteps = 4;
	}

	bRequiresInit = false;
}

void FAnimNode_AnimDynamics::TermPhysics()
{
	Bodies.Empty();
	LinearLimits.Empty();
	AngularLimits.Empty();
	Springs.Empty();

	BoundBoneReferences.Empty();

	JointOffsets.Empty();
}

void FAnimNode_AnimDynamics::UpdateLimits(USkeletalMeshComponent* SkelComp, FCSPose<FCompactPose>& MeshBases)
{
	SCOPE_CYCLE_COUNTER(STAT_AnimDynamicsLimitUpdate);

	// We're always going to use the same number so don't realloc
	LinearLimits.Empty(LinearLimits.Num());
	AngularLimits.Empty(AngularLimits.Num());
	Springs.Empty(Springs.Num());

	const FBoneContainer& BoneContainer = MeshBases.GetPose().GetBoneContainer();

	for (int32 Idx = 0; Idx < Bodies.Num(); ++Idx)
	{
		const FBoneReference& CurrentBoneRef = BoundBoneReferences[Idx];

		// If our bone isn't valid, move on
		if(!CurrentBoneRef.IsValid(BoneContainer))
		{
			continue;
		}

		FAnimPhysLinkedBody& ChainBody = Bodies[Idx];
		FAnimPhysRigidBody& RigidBody = Bodies[Idx].RigidBody.PhysBody;
		
		FAnimPhysRigidBody* PrevBody = nullptr;
		if (ChainBody.ParentBody)
		{
			PrevBody = &ChainBody.ParentBody->PhysBody;
		}

		// Get joint transform
		FCompactPoseBoneIndex BoneIndex = CurrentBoneRef.GetCompactPoseIndex(BoneContainer);
		FTransform BoundBoneTransform = MeshBases.GetComponentSpaceTransform(BoneIndex);
		FTransform ShapeTransform = BoundBoneTransform;
		
		// Local offset to joint for Body1
		FVector Body1JointOffset = LocalJointOffset;

		if (PrevBody)
		{
			// Get the correct offset
			Body1JointOffset = JointOffsets[Idx];
			// Modify the shape transform to be correct in Body0 frame
			ShapeTransform = FTransform(FQuat::Identity, -Body1JointOffset);
		}
		
		if (ConstraintSetup.bLinearFullyLocked)
		{
			// Rather than calculate prismatic limits, just lock the transform (1 limit instead of 6)
			FAnimPhys::ConstrainPositionNailed(NextTimeStep, LinearLimits, PrevBody, ShapeTransform.GetTranslation(), &RigidBody, Body1JointOffset);
		}
		else
		{
			if (ConstraintSetup.LinearXLimitType != AnimPhysLinearConstraintType::Free)
			{
				FAnimPhys::ConstrainAlongDirection(NextTimeStep, LinearLimits, PrevBody, ShapeTransform.GetTranslation(), &RigidBody, Body1JointOffset, ShapeTransform.GetRotation().GetAxisX(), FVector2D(ConstraintSetup.LinearAxesMin.X, ConstraintSetup.LinearAxesMax.X));
			}

			if (ConstraintSetup.LinearYLimitType != AnimPhysLinearConstraintType::Free)
			{
				FAnimPhys::ConstrainAlongDirection(NextTimeStep, LinearLimits, PrevBody, ShapeTransform.GetTranslation(), &RigidBody, Body1JointOffset, ShapeTransform.GetRotation().GetAxisY(), FVector2D(ConstraintSetup.LinearAxesMin.Y, ConstraintSetup.LinearAxesMax.Y));
			}

			if (ConstraintSetup.LinearZLimitType != AnimPhysLinearConstraintType::Free)
			{
				FAnimPhys::ConstrainAlongDirection(NextTimeStep, LinearLimits, PrevBody, ShapeTransform.GetTranslation(), &RigidBody, Body1JointOffset, ShapeTransform.GetRotation().GetAxisZ(), FVector2D(ConstraintSetup.LinearAxesMin.Z, ConstraintSetup.LinearAxesMax.Z));
			}
		}

		if (ConstraintSetup.AngularConstraintType == AnimPhysAngularConstraintType::Angular)
		{
#if WITH_EDITOR
			// Check the ranges are valid when running in the editor, log if something is wrong
			if(ConstraintSetup.AngularLimitsMin.X > ConstraintSetup.AngularLimitsMax.X ||
			   ConstraintSetup.AngularLimitsMin.Y > ConstraintSetup.AngularLimitsMax.Y ||
			   ConstraintSetup.AngularLimitsMin.Z > ConstraintSetup.AngularLimitsMax.Z)
			{
				UE_LOG(LogAnimation, Warning, TEXT("AnimDynamics: Min/Max angular limits for bone %s incorrect, at least one min axis value is greater than the corresponding max."), *BoundBone.BoneName.ToString());
			}
#endif

			// Add angular limits. any limit with 360+ degree range is ignored and left free.
			FAnimPhys::ConstrainAngularRange(NextTimeStep, AngularLimits, PrevBody, &RigidBody, ShapeTransform.GetRotation(), ConstraintSetup.TwistAxis, ConstraintSetup.AngularLimitsMin, ConstraintSetup.AngularLimitsMax);
		}
		else
		{
			FAnimPhys::ConstrainConeAngle(NextTimeStep, AngularLimits, PrevBody, BoundBoneTransform.GetRotation().GetAxisX(), &RigidBody, FVector(1.0f, 0.0f, 0.0f), ConstraintSetup.ConeAngle);
		}

		if(PlanarLimits.Num() > 0)
		{
			for(FAnimPhysPlanarLimit& PlanarLimit : PlanarLimits)
			{
				FTransform LimitPlaneTransform = PlanarLimit.PlaneTransform;
				if(PlanarLimit.DrivingBone.IsValid(BoneContainer))
				{
					FCompactPoseBoneIndex DrivingBoneIndex = PlanarLimit.DrivingBone.GetCompactPoseIndex(BoneContainer);
					LimitPlaneTransform *= MeshBases.GetComponentSpaceTransform(DrivingBoneIndex);// * LimitPlaneTransform;
				}
				
				FAnimPhys::ConstrainPlanar(NextTimeStep, LinearLimits, &RigidBody, LimitPlaneTransform);
			}
		}

		// Add spring if we need spring forces
		if (bAngularSpring || bLinearSpring)
		{
			FAnimPhys::CreateSpring(Springs, PrevBody, ShapeTransform.GetTranslation(), &RigidBody, FVector::ZeroVector);
			FAnimPhysSpring& NewSpring = Springs.Last();
			NewSpring.SpringConstantLinear = LinearSpringConstant;
			NewSpring.SpringConstantAngular = AngularSpringConstant;
			NewSpring.AngularTarget = ConstraintSetup.AngularTarget.GetSafeNormal();
			NewSpring.AngularTargetAxis = ConstraintSetup.AngularTargetAxis;
			NewSpring.TargetOrientationOffset = ShapeTransform.GetRotation();
			NewSpring.bApplyAngular = bAngularSpring;
			NewSpring.bApplyLinear = bLinearSpring;
		}
	}
}

void FAnimNode_AnimDynamics::PreUpdate(const UAnimInstance* InAnimInstance)
{
	const USkeletalMeshComponent* SkelComp = InAnimInstance->GetSkelMeshComponent();
	const UWorld* World = SkelComp->GetWorld();
	check(World->GetWorldSettings());
	CurrentTimeDilation = World->GetWorldSettings()->GetEffectiveTimeDilation();
}