void FAnimNode_RotationMultiplier::EvaluateBoneTransforms(USkeletalMeshComponent* SkelComp, const FBoneContainer & RequiredBones, FA2CSPose& MeshBases, TArray<FBoneTransform>& OutBoneTransforms)
{
	check(OutBoneTransforms.Num() == 0);

	if ( Multiplier != 0.f )
	{
		// Reference bone
		const TArray<FTransform> & LocalRefPose = RequiredBones.GetRefPoseArray();
		const FQuat RefQuat = LocalRefPose[TargetBone.BoneIndex].GetRotation();
		FQuat NewQuat;
		MultiplyQuatBasedOnSourceIndex(LocalRefPose, MeshBases, RotationAxisToRefer, SourceBone.BoneIndex, Multiplier, RefQuat, NewQuat);

		FTransform NewLocalTransform = MeshBases.GetLocalSpaceTransform(TargetBone.BoneIndex);
		NewLocalTransform.SetRotation(NewQuat);

		const int32 ParentIndex = RequiredBones.GetParentBoneIndex(TargetBone.BoneIndex);
		if( ParentIndex != INDEX_NONE )
		{
			const FTransform ParentTM = MeshBases.GetComponentSpaceTransform(ParentIndex);
			FTransform NewTransform = NewLocalTransform * ParentTM;
			OutBoneTransforms.Add( FBoneTransform(TargetBone.BoneIndex, NewTransform) );
		}
		else
		{
			OutBoneTransforms.Add( FBoneTransform(TargetBone.BoneIndex, NewLocalTransform) );
		}
	}
}
FQuat FAnimNode_RotationMultiplier::ExtractAngle(const TArray<FTransform> & RefPoseTransforms, FA2CSPose & MeshBases, const EBoneAxis Axis,  int32 SourceBoneIndex)
{
	// local bone transform
	const FTransform & LocalBoneTransform = MeshBases.GetLocalSpaceTransform(SourceBoneIndex);
	// local bone transform with reference rotation
	FTransform ReferenceBoneTransform = RefPoseTransforms[SourceBoneIndex];
	ReferenceBoneTransform.SetTranslation(LocalBoneTransform.GetTranslation());

	// find delta angle between the two quaternions X Axis.
	const FVector RotationAxis = GetAxisVector(Axis);
	const FVector LocalRotationVector = LocalBoneTransform.GetRotation().RotateVector(RotationAxis);
	const FVector ReferenceRotationVector = ReferenceBoneTransform.GetRotation().RotateVector(RotationAxis);

	const FQuat LocalToRefQuat = FQuat::FindBetween(LocalRotationVector, ReferenceRotationVector);
	checkSlow( LocalToRefQuat.IsNormalized() );

	// Rotate parent bone atom from position in local space to reference skeleton
	// Since our rotation rotates both vectors with shortest arc
	// we're essentially left with a quaternion that has angle difference with reference skeleton version
	const FQuat BoneQuatAligned = LocalToRefQuat * LocalBoneTransform.GetRotation();
	checkSlow( BoneQuatAligned.IsNormalized() );

	// Find that delta angle
	const FQuat DeltaQuat = (ReferenceBoneTransform.GetRotation().Inverse()) * BoneQuatAligned;
	checkSlow( DeltaQuat.IsNormalized() );

#if 0 //DEBUG_TWISTBONECONTROLLER
	UE_LOG(LogSkeletalControl, Log, TEXT("\t ExtractAngle, Bone: %s (%d)"), 
		*SourceBone.BoneName.ToString(), SourceBoneIndex);
	UE_LOG(LogSkeletalControl, Log, TEXT("\t\t Bone Quat: %s, Rot: %s, AxisX: %s"), *LocalBoneTransform.GetRotation().ToString(), *LocalBoneTransform.GetRotation().Rotator().ToString(), *LocalRotationVector.ToString() );
	UE_LOG(LogSkeletalControl, Log, TEXT("\t\t BoneRef Quat: %s, Rot: %s, AxisX: %s"), *ReferenceBoneTransform.GetRotation().ToString(), *ReferenceBoneTransform.GetRotation().Rotator().ToString(), *ReferenceRotationVector.ToString() );
	UE_LOG(LogSkeletalControl, Log, TEXT("\t\t LocalToRefQuat Quat: %s, Rot: %s"), *LocalToRefQuat.ToString(), *LocalToRefQuat.Rotator().ToString() );

	const FVector BoneQuatAlignedX = LocalBoneTransform.GetRotation().RotateVector(RotationAxis);
	UE_LOG(LogSkeletalControl, Log, TEXT("\t\t BoneQuatAligned Quat: %s, Rot: %s, AxisX: %s"), *BoneQuatAligned.ToString(), *BoneQuatAligned.Rotator().ToString(), *BoneQuatAlignedX.ToString() );
	UE_LOG(LogSkeletalControl, Log, TEXT("\t\t DeltaQuat Quat: %s, Rot: %s"), *DeltaQuat.ToString(), *DeltaQuat.Rotator().ToString() );

	FTransform BoneAtomAligned(BoneQuatAligned, ReferenceBoneTransform.GetTranslation());
	const FQuat DeltaQuatAligned = FQuat::FindBetween(BoneAtomAligned.GetScaledAxis( EAxis::X ), ReferenceBoneTransform.GetScaledAxis( EAxis::X ));
	UE_LOG(LogSkeletalControl, Log, TEXT("\t\t DeltaQuatAligned Quat: %s, Rot: %s"), *DeltaQuatAligned.ToString(), *DeltaQuatAligned.Rotator().ToString() );
	FVector DeltaAxis;
	float	DeltaAngle;
	DeltaQuat.ToAxisAndAngle(DeltaAxis, DeltaAngle);
	UE_LOG(LogSkeletalControl, Log, TEXT("\t\t DeltaAxis: %s, DeltaAngle: %f"), *DeltaAxis.ToString(), DeltaAngle );
#endif

	return DeltaQuat;
}
void FAnimNode_TwoBoneIK::EvaluateBoneTransforms(USkeletalMeshComponent* SkelComp, const FBoneContainer & RequiredBones, FA2CSPose& MeshBases, TArray<FBoneTransform>& OutBoneTransforms)
{
	check(OutBoneTransforms.Num() == 0);

	// Get indices of the lower and upper limb bones and check validity.
	bool bInvalidLimb = false;

	const int32 EndBoneIndex = IKBone.BoneIndex;
	const int32 LowerLimbIndex = RequiredBones.GetParentBoneIndex(EndBoneIndex);
	if (LowerLimbIndex == INDEX_NONE)
	{
		bInvalidLimb = true;
	}

	const int32 UpperLimbIndex = RequiredBones.GetParentBoneIndex(LowerLimbIndex);
	if (UpperLimbIndex == INDEX_NONE)
	{
		bInvalidLimb = true;
	}

	const bool bInBoneSpace = (EffectorLocationSpace == BCS_ParentBoneSpace) || (EffectorLocationSpace == BCS_BoneSpace);
	const int32 EffectorSpaceBoneIndex = bInBoneSpace ? RequiredBones.GetPoseBoneIndexForBoneName(EffectorSpaceBoneName) : INDEX_NONE;

	if (bInBoneSpace && ((EffectorSpaceBoneIndex == INDEX_NONE) || !RequiredBones.Contains(EffectorSpaceBoneIndex)))
	{
		bInvalidLimb = true;
	}

	// If we walked past the root, this controlled is invalid, so return no affected bones.
	if( bInvalidLimb )
	{
		return;
	}

	// Get Local Space transforms for our bones. We do this first in case they already are local.
	// As right after we get them in component space. (And that does the auto conversion).
	// We might save one transform by doing local first...
	const FTransform EndBoneLocalTransform = MeshBases.GetLocalSpaceTransform(IKBone.BoneIndex);

	// Now get those in component space...
	FTransform UpperLimbCSTransform = MeshBases.GetComponentSpaceTransform(UpperLimbIndex);
	FTransform LowerLimbCSTransform = MeshBases.GetComponentSpaceTransform(LowerLimbIndex);
	FTransform EndBoneCSTransform = MeshBases.GetComponentSpaceTransform(IKBone.BoneIndex);

	// Get current position of root of limb.
	// All position are in Component space.
	const FVector RootPos = UpperLimbCSTransform.GetTranslation();
	const FVector InitialJointPos = LowerLimbCSTransform.GetTranslation();
	const FVector InitialEndPos = EndBoneCSTransform.GetTranslation();

	// Transform EffectorLocation from EffectorLocationSpace to ComponentSpace.
	FTransform EffectorTransform(EffectorLocation);
	FAnimationRuntime::ConvertBoneSpaceTransformToCS(SkelComp, MeshBases, EffectorTransform, EffectorSpaceBoneIndex, EffectorLocationSpace);

	// This is our reach goal.
	FVector DesiredPos = EffectorTransform.GetTranslation();
	FVector DesiredDelta = DesiredPos - RootPos;
	float DesiredLength = DesiredDelta.Size();

	// Check to handle case where DesiredPos is the same as RootPos.
	FVector	DesiredDir;
	if (DesiredLength < (float)KINDA_SMALL_NUMBER)
	{
		DesiredLength = (float)KINDA_SMALL_NUMBER;
		DesiredDir = FVector(1,0,0);
	}
	else
	{
		DesiredDir = DesiredDelta / DesiredLength;
	}

	// Get joint target (used for defining plane that joint should be in).
	FTransform JointTargetTransform(JointTargetLocation);
	const int32 JointTargetSpaceBoneIndex = (JointTargetLocationSpace == BCS_ParentBoneSpace || JointTargetLocationSpace == BCS_BoneSpace) ? RequiredBones.GetPoseBoneIndexForBoneName(JointTargetSpaceBoneName) : INDEX_NONE;
	FAnimationRuntime::ConvertBoneSpaceTransformToCS(SkelComp, MeshBases, JointTargetTransform, JointTargetSpaceBoneIndex, JointTargetLocationSpace);

	FVector	JointTargetPos = JointTargetTransform.GetTranslation();
	FVector JointTargetDelta = JointTargetPos - RootPos;
	float JointTargetLength = JointTargetDelta.Size();

	// Same check as above, to cover case when JointTarget position is the same as RootPos.
	FVector JointPlaneNormal, JointBendDir;
	if (JointTargetLength < (float)KINDA_SMALL_NUMBER)
	{
		JointBendDir = FVector(0,1,0);
		JointPlaneNormal = FVector(0,0,1);
	}
	else
	{
		JointPlaneNormal = DesiredDir ^ JointTargetDelta;

		// If we are trying to point the limb in the same direction that we are supposed to displace the joint in, 
		// we have to just pick 2 random vector perp to DesiredDir and each other.
		if (JointPlaneNormal.Size() < (float)KINDA_SMALL_NUMBER)
		{
			DesiredDir.FindBestAxisVectors(JointPlaneNormal, JointBendDir);
		}
		else
		{
			JointPlaneNormal.Normalize();

			// Find the final member of the reference frame by removing any component of JointTargetDelta along DesiredDir.
			// This should never leave a zero vector, because we've checked DesiredDir and JointTargetDelta are not parallel.
			JointBendDir = JointTargetDelta - ((JointTargetDelta | DesiredDir) * DesiredDir);
			JointBendDir.Normalize();
		}
	}

	// Find lengths of upper and lower limb in the ref skeleton.
	// Use actual sizes instead of ref skeleton, so we take into account translation and scaling from other bone controllers.
	float LowerLimbLength = (InitialEndPos - InitialJointPos).Size();
	float UpperLimbLength = (InitialJointPos - RootPos).Size();
	float MaxLimbLength	= LowerLimbLength + UpperLimbLength;

	if (bAllowStretching)
	{
		const float ScaleRange = StretchLimits.Y - StretchLimits.X;
		if( ScaleRange > KINDA_SMALL_NUMBER && MaxLimbLength > KINDA_SMALL_NUMBER )
		{
			const float ReachRatio = DesiredLength / MaxLimbLength;
			const float ScalingFactor = (StretchLimits.Y - 1.f) * FMath::Clamp<float>((ReachRatio - StretchLimits.X) / ScaleRange, 0.f, 1.f);
			if (ScalingFactor > KINDA_SMALL_NUMBER)
			{
				LowerLimbLength *= (1.f + ScalingFactor);
				UpperLimbLength *= (1.f + ScalingFactor);
				MaxLimbLength	*= (1.f + ScalingFactor);
			}
		}
	}

	FVector OutEndPos = DesiredPos;
	FVector OutJointPos = InitialJointPos;

	// If we are trying to reach a goal beyond the length of the limb, clamp it to something solvable and extend limb fully.
	if (DesiredLength > MaxLimbLength)
	{
		OutEndPos = RootPos + (MaxLimbLength * DesiredDir);
		OutJointPos = RootPos + (UpperLimbLength * DesiredDir);
	}
	else
	{
		// So we have a triangle we know the side lengths of. We can work out the angle between DesiredDir and the direction of the upper limb
		// using the sin rule:
		const float TwoAB = 2.f * UpperLimbLength * DesiredLength;

		const float CosAngle = (TwoAB != 0.f) ? ((UpperLimbLength*UpperLimbLength) + (DesiredLength*DesiredLength) - (LowerLimbLength*LowerLimbLength)) / TwoAB : 0.f;

		// If CosAngle is less than 0, the upper arm actually points the opposite way to DesiredDir, so we handle that.
		const bool bReverseUpperBone = (CosAngle < 0.f);

		// If CosAngle is greater than 1.f, the triangle could not be made - we cannot reach the target.
		// We just have the two limbs double back on themselves, and EndPos will not equal the desired EffectorLocation.
		if ((CosAngle > 1.f) || (CosAngle < -1.f))
		{
			// Because we want the effector to be a positive distance down DesiredDir, we go back by the smaller section.
			if (UpperLimbLength > LowerLimbLength)
			{
				OutJointPos = RootPos + (UpperLimbLength * DesiredDir);
				OutEndPos = OutJointPos - (LowerLimbLength * DesiredDir);
			}
			else
			{
				OutJointPos = RootPos - (UpperLimbLength * DesiredDir);
				OutEndPos = OutJointPos + (LowerLimbLength * DesiredDir);
			}
		}
		else
		{
			// Angle between upper limb and DesiredDir
			const float Angle = FMath::Acos(CosAngle);

			// Now we calculate the distance of the joint from the root -> effector line.
			// This forms a right-angle triangle, with the upper limb as the hypotenuse.
			const float JointLineDist = UpperLimbLength * FMath::Sin(Angle);

			// And the final side of that triangle - distance along DesiredDir of perpendicular.
			// ProjJointDistSqr can't be neg, because JointLineDist must be <= UpperLimbLength because appSin(Angle) is <= 1.
			const float ProjJointDistSqr = (UpperLimbLength*UpperLimbLength) - (JointLineDist*JointLineDist);
			// although this shouldn't be ever negative, sometimes Xbox release produces -0.f, causing ProjJointDist to be NaN
			// so now I branch it. 						
			float ProjJointDist = (ProjJointDistSqr>0.f)? FMath::Sqrt(ProjJointDistSqr) : 0.f;
			if( bReverseUpperBone )
			{
				ProjJointDist *= -1.f;
			}

			// So now we can work out where to put the joint!
			OutJointPos = RootPos + (ProjJointDist * DesiredDir) + (JointLineDist * JointBendDir);
		}
	}

	// Update transform for upper bone.
	{
		// Get difference in direction for old and new joint orientations
		FVector const OldDir = (InitialJointPos - RootPos).SafeNormal();
		FVector const NewDir = (OutJointPos - RootPos).SafeNormal();
		// Find Delta Rotation take takes us from Old to New dir
		FQuat const DeltaRotation = FQuat::FindBetween(OldDir, NewDir);
		// Rotate our Joint quaternion by this delta rotation
		UpperLimbCSTransform.SetRotation( DeltaRotation * UpperLimbCSTransform.GetRotation() );
		// And put joint where it should be.
		UpperLimbCSTransform.SetTranslation( RootPos );

		// Order important. First bone is upper limb.
		OutBoneTransforms.Add( FBoneTransform(UpperLimbIndex, UpperLimbCSTransform) );
	}

	// Update transform for lower bone.
	{
		// Get difference in direction for old and new joint orientations
		FVector const OldDir = (InitialEndPos - InitialJointPos).SafeNormal();
		FVector const NewDir = (OutEndPos - OutJointPos).SafeNormal();

		// Find Delta Rotation take takes us from Old to New dir
		FQuat const DeltaRotation = FQuat::FindBetween(OldDir, NewDir);
		// Rotate our Joint quaternion by this delta rotation
		LowerLimbCSTransform.SetRotation( DeltaRotation * LowerLimbCSTransform.GetRotation() );
		// And put joint where it should be.
		LowerLimbCSTransform.SetTranslation( OutJointPos );

		// Order important. Second bone is lower limb.
		OutBoneTransforms.Add( FBoneTransform(LowerLimbIndex, LowerLimbCSTransform) );
	}

	// Update transform for end bone.
	{
		if( bTakeRotationFromEffectorSpace )
		{
			EndBoneCSTransform.SetRotation( EffectorTransform.GetRotation() );
		}
		else if( bMaintainEffectorRelRot )
		{
			EndBoneCSTransform = EndBoneLocalTransform * LowerLimbCSTransform;
		}

		// Set correct location for end bone.
		EndBoneCSTransform.SetTranslation(OutEndPos);

		// Order important. Third bone is End Bone.
		OutBoneTransforms.Add( FBoneTransform(IKBone.BoneIndex, EndBoneCSTransform) );
	}

	// Make sure we have correct number of bones
	check(OutBoneTransforms.Num() == 3);
}
Esempio n. 4
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void FAnimNode_Fabrik::EvaluateBoneTransforms(USkeletalMeshComponent* SkelComp, const FBoneContainer& RequiredBones, FA2CSPose& MeshBases, TArray<FBoneTransform>& OutBoneTransforms)
{
	// IsValidToEvaluate validated our inputs, we don't need to check pre-requisites again.
	int32 const RootIndex = RootBone.BoneIndex;

	// Update EffectorLocation if it is based off a bone position
	FTransform CSEffectorTransform = FTransform(EffectorTransform);
	FAnimationRuntime::ConvertBoneSpaceTransformToCS(SkelComp, MeshBases, CSEffectorTransform, EffectorTransformBone.BoneIndex, EffectorTransformSpace);
	FVector const CSEffectorLocation = CSEffectorTransform.GetLocation();

	// @fixme - we need better to draw widgets and debug information in editor.
#if !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
	if (bEnableDebugDraw)
	{
		// Show end effector position.
		DrawDebugBox(SkelComp->GetWorld(), CSEffectorLocation, FVector(Precision), FColor::Green, true, 0.1f);
		DrawDebugCoordinateSystem(SkelComp->GetWorld(), CSEffectorLocation, CSEffectorTransform.GetRotation().Rotator(), 5.f, true, 0.1f);
	}
#endif

	// Gather all bone indices between root and tip.
	TArray<int32> BoneIndices;
	{
		int32 BoneIndex = TipBone.BoneIndex;
		do 
		{
			BoneIndices.Insert(BoneIndex, 0);
			BoneIndex = RequiredBones.GetParentBoneIndex(BoneIndex);
		} while (BoneIndex != RootIndex);
		BoneIndices.Insert(BoneIndex, 0);
	}

	// Maximum length of skeleton segment at full extension
	float MaximumReach = 0;

	// Gather transforms
	int32 const NumTransforms = BoneIndices.Num();
	OutBoneTransforms.AddUninitialized(NumTransforms);

	// Gather chain links. These are non zero length bones.
	TArray<FABRIKChainLink> Chain;
	Chain.Reserve(NumTransforms);

	// Start with Root Bone
	{
		int32 const & RootBoneIndex = BoneIndices[0];
		FTransform const BoneCSTransform = MeshBases.GetComponentSpaceTransform(RootBoneIndex);
		OutBoneTransforms[0] = FBoneTransform(RootBoneIndex, BoneCSTransform);

		Chain.Add(FABRIKChainLink(BoneCSTransform.GetLocation(), 0.f, RootBoneIndex, 0));
	}

	// Go through remaining transforms
	for (int32 TransformIndex = 1; TransformIndex < NumTransforms; TransformIndex++)
	{
		int32 const & BoneIndex = BoneIndices[TransformIndex];

		FTransform const BoneCSTransform = MeshBases.GetComponentSpaceTransform(BoneIndex);
		FVector const BoneCSPosition = BoneCSTransform.GetLocation();
		OutBoneTransforms[TransformIndex] = FBoneTransform(BoneIndex, BoneCSTransform);

		// Calculate the combined length of this segment of skeleton
		float const BoneLength = FVector::Dist(BoneCSPosition, OutBoneTransforms[TransformIndex-1].Transform.GetLocation());

		if (!FMath::IsNearlyZero(BoneLength))
		{
			Chain.Add(FABRIKChainLink(BoneCSPosition, BoneLength, BoneIndex, TransformIndex));
			MaximumReach += BoneLength;
		}
		else
		{
			// Mark this transform as a zero length child of the last link.
			// It will inherit position and delta rotation from parent link.
			FABRIKChainLink & ParentLink = Chain[Chain.Num()-1];
			ParentLink.ChildZeroLengthTransformIndices.Add(TransformIndex);
		}
	}

	bool bBoneLocationUpdated = false;
	float const RootToTargetDist = FVector::Dist(Chain[0].Position, CSEffectorLocation);
	int32 const NumChainLinks = Chain.Num();

	// FABRIK algorithm - bone translation calculation
	// If the effector is further away than the distance from root to tip, simply move all bones in a line from root to effector location
	if (RootToTargetDist > MaximumReach)
	{
		for (int32 LinkIndex = 1; LinkIndex < NumChainLinks; LinkIndex++)
		{
			FABRIKChainLink const & ParentLink = Chain[LinkIndex - 1];
			FABRIKChainLink & CurrentLink = Chain[LinkIndex];
			CurrentLink.Position = ParentLink.Position + (CSEffectorLocation - ParentLink.Position).GetUnsafeNormal() * CurrentLink.Length;
		}
		bBoneLocationUpdated = true;
	}
	else // Effector is within reach, calculate bone translations to position tip at effector location
	{
		int32 const TipBoneLinkIndex = NumChainLinks - 1;

		// Check distance between tip location and effector location
		float Slop = FVector::Dist(Chain[TipBoneLinkIndex].Position, CSEffectorLocation);
		if (Slop > Precision)
		{
			// Set tip bone at end effector location.
			Chain[TipBoneLinkIndex].Position = CSEffectorLocation;

			int32 IterationCount = 0;
			while ((Slop > Precision) && (IterationCount++ < MaxIterations))
			{
				// "Forward Reaching" stage - adjust bones from end effector.
				for (int32 LinkIndex = TipBoneLinkIndex - 1; LinkIndex > 0; LinkIndex--)
				{
					FABRIKChainLink & CurrentLink = Chain[LinkIndex];
					FABRIKChainLink const & ChildLink = Chain[LinkIndex + 1];

					CurrentLink.Position = ChildLink.Position + (CurrentLink.Position - ChildLink.Position).GetUnsafeNormal() * ChildLink.Length;
				}

				// "Backward Reaching" stage - adjust bones from root.
				for (int32 LinkIndex = 1; LinkIndex < TipBoneLinkIndex; LinkIndex++)
				{
					FABRIKChainLink const & ParentLink = Chain[LinkIndex - 1];
					FABRIKChainLink & CurrentLink = Chain[LinkIndex];

					CurrentLink.Position = ParentLink.Position + (CurrentLink.Position - ParentLink.Position).GetUnsafeNormal() * CurrentLink.Length;
				}

				// Re-check distance between tip location and effector location
				// Since we're keeping tip on top of effector location, check with its parent bone.
				Slop = FMath::Abs(Chain[TipBoneLinkIndex].Length - FVector::Dist(Chain[TipBoneLinkIndex - 1].Position, CSEffectorLocation));
			}

			// Place tip bone based on how close we got to target.
			{
				FABRIKChainLink const & ParentLink = Chain[TipBoneLinkIndex - 1];
				FABRIKChainLink & CurrentLink = Chain[TipBoneLinkIndex];

				CurrentLink.Position = ParentLink.Position + (CurrentLink.Position - ParentLink.Position).GetUnsafeNormal() * CurrentLink.Length;
			}

			bBoneLocationUpdated = true;
		}
	}

	// If we moved some bones, update bone transforms.
	if (bBoneLocationUpdated)
	{
		// First step: update bone transform positions from chain links.
		for (int32 LinkIndex = 0; LinkIndex < NumChainLinks; LinkIndex++)
		{
			FABRIKChainLink const & ChainLink = Chain[LinkIndex];
			OutBoneTransforms[ChainLink.TransformIndex].Transform.SetTranslation(ChainLink.Position);

			// If there are any zero length children, update position of those
			int32 const NumChildren = ChainLink.ChildZeroLengthTransformIndices.Num();
			for (int32 ChildIndex = 0; ChildIndex < NumChildren; ChildIndex++)
			{
				OutBoneTransforms[ChainLink.ChildZeroLengthTransformIndices[ChildIndex]].Transform.SetTranslation(ChainLink.Position);
			}
		}

		// FABRIK algorithm - re-orientation of bone local axes after translation calculation
		for (int32 LinkIndex = 0; LinkIndex < NumChainLinks - 1; LinkIndex++)
		{
			FABRIKChainLink const & CurrentLink = Chain[LinkIndex];
			FABRIKChainLink const & ChildLink = Chain[LinkIndex + 1];

			// Calculate pre-translation vector between this bone and child
			FVector const OldDir = (GetCurrentLocation(MeshBases, ChildLink.BoneIndex) - GetCurrentLocation(MeshBases, CurrentLink.BoneIndex)).GetUnsafeNormal();

			// Get vector from the post-translation bone to it's child
			FVector const NewDir = (ChildLink.Position - CurrentLink.Position).GetUnsafeNormal();

			// Calculate axis of rotation from pre-translation vector to post-translation vector
			FVector const RotationAxis = FVector::CrossProduct(OldDir, NewDir).GetSafeNormal();
			float const RotationAngle = FMath::Acos(FVector::DotProduct(OldDir, NewDir));
			FQuat const DeltaRotation = FQuat(RotationAxis, RotationAngle);
			// We're going to multiply it, in order to not have to re-normalize the final quaternion, it has to be a unit quaternion.
			checkSlow(DeltaRotation.IsNormalized());

			// Calculate absolute rotation and set it
			FTransform& CurrentBoneTransform = OutBoneTransforms[CurrentLink.TransformIndex].Transform;
			CurrentBoneTransform.SetRotation(DeltaRotation * CurrentBoneTransform.GetRotation());

			// Update zero length children if any
			int32 const NumChildren = CurrentLink.ChildZeroLengthTransformIndices.Num();
			for (int32 ChildIndex = 0; ChildIndex < NumChildren; ChildIndex++)
			{
				FTransform& ChildBoneTransform = OutBoneTransforms[CurrentLink.ChildZeroLengthTransformIndices[ChildIndex]].Transform;
				ChildBoneTransform.SetRotation(DeltaRotation * ChildBoneTransform.GetRotation());
			}
		}
	}

	// Special handling for tip bone's rotation.
	int32 const TipBoneTransformIndex = OutBoneTransforms.Num() - 1;
	switch (EffectorRotationSource)
	{
	case BRS_KeepLocalSpaceRotation:
		OutBoneTransforms[TipBoneTransformIndex].Transform = MeshBases.GetLocalSpaceTransform(BoneIndices[TipBoneTransformIndex]) * OutBoneTransforms[TipBoneTransformIndex - 1].Transform;
		break;
	case BRS_CopyFromTarget:
		OutBoneTransforms[TipBoneTransformIndex].Transform.SetRotation(CSEffectorTransform.GetRotation());
		break;
	case BRS_KeepComponentSpaceRotation:
		// Don't change the orientation at all
		break;
	default:
		break;
	}
}