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);
}
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;
}
}