UnrealEngineUWP/Engine/Plugins/Experimental/MeshModelingToolsetExp/Source/MeshModelingToolsExp/Private/SkinWeightsPaintTool.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

#include "SkinWeightsPaintTool.h"

#include "InteractiveToolManager.h"
#include "ToolBuilderUtil.h"
#include "SkeletalMeshAttributes.h"
#include "SkeletalDebugRendering.h"
#include "Math/UnrealMathUtility.h"
#include "Components/SkeletalMeshComponent.h"

#include "TargetInterfaces/PrimitiveComponentBackedTarget.h"
#include "ModelingToolTargetUtil.h"

#include "MeshDescription.h"


#define LOCTEXT_NAMESPACE "USkinWeightsPaintTool"

// Any weight below this value is ignored, since it won't be representable in a uint8.
const float MinimumWeightThreshold = 1.0f / 255.0f;


void FMeshSkinWeightsChange::Apply(UObject* Object)
{
	USkinWeightsPaintTool* Tool = CastChecked<USkinWeightsPaintTool>(Object);

	Tool->ExternalUpdateValues(BoneName, NewWeights);
}

void FMeshSkinWeightsChange::Revert(UObject* Object)
{
	USkinWeightsPaintTool* Tool = CastChecked<USkinWeightsPaintTool>(Object);

	Tool->ExternalUpdateValues(BoneName, OldWeights);
}

void FMeshSkinWeightsChange::UpdateValues(const TArray<int32>& Indices, const TArray<float>& OldValues, const TArray<float>& NewValues)
{
	const int32 NumIndices = Indices.Num();
	for (int32 i = 0; i < NumIndices; i++)
	{
		NewWeights.Add(Indices[i], NewValues[i]);
		OldWeights.FindOrAdd(Indices[i], OldValues[i]);
	}
}


/*
 * ToolBuilder
 */

UMeshSurfacePointTool* USkinWeightsPaintToolBuilder::CreateNewTool(const FToolBuilderState& SceneState) const
{
	return NewObject<USkinWeightsPaintTool>(SceneState.ToolManager);
}


void USkinWeightsPaintTool::Setup()
{
	UDynamicMeshBrushTool::Setup();

	IPrimitiveComponentBackedTarget* TargetComponent = Cast<IPrimitiveComponentBackedTarget>(Target);
	USkeletalMeshComponent* Component = Cast<USkeletalMeshComponent>(TargetComponent->GetOwnerComponent());

	// hide strength and falloff
	BrushProperties->RestoreProperties(this);

	ToolProps = NewObject<USkinWeightsPaintToolProperties>(this);
	ToolProps->RestoreProperties(this);
	if (Component && Component->GetSkeletalMesh())
	{
		// Get all non-virtual bones
		// TArray<int32> BoneIndices;
		USkeletalMesh& SkeletalMesh = *Component->GetSkeletalMesh();
		// SkeletalMesh.RefSkeleton.GetRawRefBoneInfo();
		

		// Initialize the bone browser
		FCurveEvaluationOption CurveEvalOption(
				Component->GetAllowedAnimCurveEvaluate(),
				&Component->GetDisallowedAnimCurvesEvaluation(),
				0 /* Always use the highest LOD */
				);
		BoneContainer.InitializeTo(Component->RequiredBones, CurveEvalOption, SkeletalMesh);

		ToolProps->SkeletalMesh = Component->GetSkeletalMesh();
		ToolProps->CurrentBone.Initialize(BoneContainer);

		// Pick the first root bone as the initial selection.
		PendingCurrentBone = Component->GetSkeletalMesh()->GetRefSkeleton().GetBoneName(0);
		ToolProps->CurrentBone.BoneName = PendingCurrentBone.GetValue();

		// Update the skeleton drawing information from the original bind pose
		MaxDrawRadius = Component->Bounds.SphereRadius * 0.0025f;
	}
	AddToolPropertySource(ToolProps);

	UpdateBonePositionInfos(MaxDrawRadius);

	// configure preview mesh
	PreviewMesh->SetTangentsMode(EDynamicMeshComponentTangentsMode::AutoCalculated);
	//PreviewMesh->EnableWireframe(SelectionProps->bShowWireframe);
	PreviewMesh->SetShadowsEnabled(false);

	// enable vtx colors on preview mesh
	PreviewMesh->EditMesh([](FDynamicMesh3& Mesh)
	{
		Mesh.EnableAttributes();
		Mesh.Attributes()->DisablePrimaryColors();
		Mesh.Attributes()->EnablePrimaryColors();
		// Create an overlay that has no split elements, init with zero value.
		Mesh.Attributes()->PrimaryColors()->CreateFromPredicate([](int ParentVID, int TriIDA, int TriIDB){return true;}, 0.f);
	});

	// build octree
	VerticesOctree.Initialize(PreviewMesh->GetMesh(), true);

	UMaterialInterface* VtxColorMaterial = GetToolManager()->GetContextQueriesAPI()->GetStandardMaterial(EStandardToolContextMaterials::VertexColorMaterial);
	if (VtxColorMaterial != nullptr)
	{
		PreviewMesh->SetOverrideRenderMaterial(VtxColorMaterial);
	}

	RecalculateBrushRadius();

	GetToolManager()->DisplayMessage(
		LOCTEXT("OnStartSkinWeightsPaint", "Paint per-bone skin weights. [ and ] change brush size, Ctrl to Erase/Subtract, Shift to Smooth"),
		EToolMessageLevel::UserNotification);

	EditedMesh = MakeUnique<FMeshDescription>();
	*EditedMesh = *UE::ToolTarget::GetMeshDescription(Target);

	InitializeSkinWeights();

	CurrentBoneWatcher.Initialize([this]() { return ToolProps->CurrentBone; },
		[this](FBoneReference NewValue) { PendingCurrentBone = NewValue.BoneName; }, ToolProps->CurrentBone);

	bVisibleWeightsValid = false;
}



void USkinWeightsPaintTool::RegisterActions(FInteractiveToolActionSet& ActionSet)
{
	UDynamicMeshBrushTool::RegisterActions(ActionSet);
}




void USkinWeightsPaintTool::OnTick(float DeltaTime)
{
	CurrentBoneWatcher.CheckAndUpdate();

	if (bStampPending)
	{
		ApplyStamp(LastStamp);
		bStampPending = false;
	}

	if (PendingCurrentBone.IsSet())
	{
		UpdateCurrentBone(*PendingCurrentBone);
		PendingCurrentBone.Reset();
	}

	if (bVisibleWeightsValid == false)
	{
		UpdateBoneVisualization();
		bVisibleWeightsValid = true;
	}
}




void USkinWeightsPaintTool::Render(IToolsContextRenderAPI* RenderAPI)
{
	UDynamicMeshBrushTool::Render(RenderAPI);

	// FIXME: Make selective.
	RenderBonePositions(RenderAPI->GetPrimitiveDrawInterface());
}







bool USkinWeightsPaintTool::HitTest(const FRay& Ray, FHitResult& OutHit)
{
	bool bHit = UDynamicMeshBrushTool::HitTest(Ray, OutHit);
	//if (bHit && SelectionProps->bHitBackFaces == false)
	//{
	//	const FDynamicMesh3* SourceMesh = PreviewMesh->GetPreviewDynamicMesh();
	//	FVector3d Normal, Centroid;
	//	double Area;
	//	SourceMesh->GetTriInfo(OutHit.FaceIndex, Normal, Area, Centroid);
	//	FViewCameraState StateOut;
	//	GetToolManager()->GetContextQueriesAPI()->GetCurrentViewState(StateOut);
	//	FVector3d LocalEyePosition(ComponentTarget->GetWorldTransform().InverseTransformPosition(StateOut.Position));

	//	if (Normal.Dot((Centroid - LocalEyePosition)) > 0)
	//	{
	//		bHit = false;
	//	}
	//}
	return bHit;
}


void USkinWeightsPaintTool::OnBeginDrag(const FRay& WorldRay)
{
	UDynamicMeshBrushTool::OnBeginDrag(WorldRay);

	PreviewBrushROI.Reset();
	if (IsInBrushStroke())
	{
		bInRemoveStroke = GetCtrlToggle();
		bInSmoothStroke = GetShiftToggle();
		BeginChange();
		StartStamp = UBaseBrushTool::LastBrushStamp;
		LastStamp = StartStamp;
		bStampPending = true;
	}
}



void USkinWeightsPaintTool::OnUpdateDrag(const FRay& WorldRay)
{
	UDynamicMeshBrushTool::OnUpdateDrag(WorldRay);
	if (IsInBrushStroke())
	{
		LastStamp = UBaseBrushTool::LastBrushStamp;
		bStampPending = true;
	}
}



void USkinWeightsPaintTool::OnEndDrag(const FRay& Ray)
{
	UDynamicMeshBrushTool::OnEndDrag(Ray);

	bInRemoveStroke = false;
	bInSmoothStroke = false;
	bStampPending = false;

	// close change record
	TUniquePtr<FMeshSkinWeightsChange> Change = EndChange();

	GetToolManager()->BeginUndoTransaction(LOCTEXT("BoneWeightValuesChange", "Paint"));

	GetToolManager()->EmitObjectChange(this, MoveTemp(Change), LOCTEXT("BoneWeightValuesChange", "Paint"));

	GetToolManager()->EndUndoTransaction();
}


bool USkinWeightsPaintTool::OnUpdateHover(const FInputDeviceRay& DevicePos)
{
	UDynamicMeshBrushTool::OnUpdateHover(DevicePos);

	// todo get rid of this redundant hit test!
	FHitResult OutHit;
	if (UDynamicMeshBrushTool::HitTest(DevicePos.WorldRay, OutHit))
	{
		PreviewBrushROI.Reset();
		CalculateVertexROI(LastBrushStamp, PreviewBrushROI);
	}

	return true;
}



void USkinWeightsPaintTool::CalculateVertexROI(const FBrushStampData& Stamp, TArray<int>& VertexROI)
{
	using namespace UE::Geometry;
	IPrimitiveComponentBackedTarget* TargetComponent = Cast<IPrimitiveComponentBackedTarget>(Target);
	FTransform3d Transform(TargetComponent->GetWorldTransform());
	FVector3d StampPosLocal = Transform.InverseTransformPosition((FVector3d)Stamp.WorldPosition);

	float RadiusSqr = CurrentBrushRadius * CurrentBrushRadius;
	const FDynamicMesh3* Mesh = PreviewMesh->GetPreviewDynamicMesh();
	FAxisAlignedBox3d QueryBox(StampPosLocal, CurrentBrushRadius);
	VerticesOctree.RangeQuery(QueryBox,
		[&](int32 VertexID) { return FVector3d::DistSquared(Mesh->GetVertex(VertexID), StampPosLocal) < RadiusSqr; },
		VertexROI);
}


FVector4f USkinWeightsPaintTool::WeightToColor(float Value)
{
	Value = FMath::Clamp(Value, 0.0f, 1.0f);

	{
		// A close approximation of the skeletal mesh editor's bone weight ramp. 
		const FLinearColor HSV((1.0f - Value) * 285.0f, 100.0f, 85.0f);
		return UE::Geometry::ToVector4<float>(HSV.HSVToLinearRGB());
	}
}


void USkinWeightsPaintTool::UpdateBoneVisualization()
{
	if (!SkinWeightsMap.Contains(CurrentBone))
		return;

	TArray<float>& SkinWeightsData = *SkinWeightsMap.Find(CurrentBone);

	// update mesh with new value colors
	PreviewMesh->EditMesh([&](FDynamicMesh3& Mesh)
	{
		UE::Geometry::FDynamicMeshColorOverlay* ColorOverlay = Mesh.Attributes()->PrimaryColors();
		for (int32 ElementId : ColorOverlay->ElementIndicesItr())
		{
			const int32 VertexId = ColorOverlay->GetParentVertex(ElementId);
			const float Value = SkinWeightsData[VertexId];
			const FVector4f Color(WeightToColor(Value));
			ColorOverlay->SetElement(ElementId, Color);
		}
	});
}


double USkinWeightsPaintTool::CalculateBrushFalloff(double Distance) const
{
	double f = FMathd::Clamp(1.0 - BrushProperties->BrushFalloffAmount, 0.0, 1.0);
	double d = Distance / CurrentBrushRadius;
	double w = 1;
	if (d > f)
	{
		d = FMathd::Clamp((d - f) / (1.0 - f), 0.0, 1.0);
		w = (1.0 - d * d);
		w = w * w * w;
	}
	return w;
}



void USkinWeightsPaintTool::ApplyStamp(const FBrushStampData& Stamp)
{
	using namespace UE::Geometry;
	
	// FIXME: Move to earlier.
	if (!SkinWeightsMap.Contains(CurrentBone))
		return;

	IPrimitiveComponentBackedTarget* TargetComponent = Cast<IPrimitiveComponentBackedTarget>(Target);
	FTransform3d Transform(TargetComponent->GetWorldTransform());
	FVector3d StampPosLocal = Transform.InverseTransformPosition((FVector3d)Stamp.WorldPosition);

	TArray<int32> ROIVertices;
	CalculateVertexROI(Stamp, ROIVertices);
	const int32 NumROIVertices = ROIVertices.Num();

	TArray<float> ROIBefore, ROIAfter;
	ROIBefore.SetNum(NumROIVertices);
	ROIAfter.SetNum(NumROIVertices);

	TArray<float>& SkinWeightsData = *SkinWeightsMap.Find(CurrentBone);

	const FDynamicMesh3* CurrentMesh = PreviewMesh->GetMesh();
	if (bInSmoothStroke)
	{
		const float SmoothSpeed = 0.25f;

		for (int32 Index = 0; Index < NumROIVertices; ++Index)
		{
			const int32 VertexId = ROIVertices[Index];
			FVector3d Position = CurrentMesh->GetVertex(VertexId);
			float ValueSum = 0, WeightSum = 0;
			for (int32 NeighborVertexId : CurrentMesh->VtxVerticesItr(VertexId))
			{
				FVector3d NbrPos = CurrentMesh->GetVertex(NeighborVertexId);
				const float Weight = FMathf::Clamp(1.0f / FVector3d::DistSquared(NbrPos, Position), 0.0001f, 1000.0f);
				ValueSum += Weight * SkinWeightsData[NeighborVertexId];
				WeightSum += Weight;
			}
			ValueSum /= WeightSum;

			const float Falloff = float(CalculateBrushFalloff(FVector3d::Dist(Position, StampPosLocal)));
			const float NewValue = FMathf::Lerp(SkinWeightsData[VertexId], ValueSum, SmoothSpeed*Falloff);

			ROIBefore[Index] = SkinWeightsData[VertexId];
			ROIAfter[Index] = FMath::Clamp(NewValue, 0.0f, 1.0f);
		}
	}
	else
	{
		const bool bInvert = bInRemoveStroke;
		const float Sign = (bInvert) ? -1.0f : 1.0f;
		const float UseStrength = Sign * BrushProperties->BrushStrength;
		for (int32 Index = 0; Index < NumROIVertices; ++Index)
		{
			const int32 VertexId = ROIVertices[Index];
			const FVector3d Position = CurrentMesh->GetVertex(VertexId);
			const float Falloff = (float)CalculateBrushFalloff(FVector3d::Dist(Position, StampPosLocal));
			ROIBefore[Index] = SkinWeightsData[VertexId];
			ROIAfter[Index] = FMath::Clamp(ROIBefore[Index] + UseStrength * Falloff, 0.0f, 1.0f);
		}
	}

	// track changes
	if (ActiveChange)
	{
		ActiveChange->UpdateValues(ROIVertices, ROIBefore, ROIAfter);
	}

	// update values and colors
	PreviewMesh->DeferredEditMesh([&](FDynamicMesh3& Mesh)
	{
		TArray<int> ElementIds;
		FDynamicMeshColorOverlay* ColorOverlay = Mesh.Attributes()->PrimaryColors();
		for (int32 Index = 0; Index < NumROIVertices; ++Index)
		{
			const int32 VertexId = ROIVertices[Index];
			SkinWeightsData[VertexId] = ROIAfter[Index];
			FVector4f NewColor(WeightToColor(ROIAfter[Index]));
			ColorOverlay->GetVertexElements(VertexId, ElementIds);
			for (int ElementId : ElementIds)
			{
				ColorOverlay->SetElement(ElementId, NewColor);
			}
			ElementIds.Reset();
		}
	}, false);
	PreviewMesh->NotifyDeferredEditCompleted(UPreviewMesh::ERenderUpdateMode::FastUpdate, EMeshRenderAttributeFlags::VertexColors, false);

}


void USkinWeightsPaintTool::UpdateCurrentBone(const FName& BoneName)
{
	CurrentBone = BoneName;

	bVisibleWeightsValid = false;
}


void USkinWeightsPaintTool::OnShutdown(EToolShutdownType ShutdownType)
{
	BrushProperties->SaveProperties(this);

	if (ShutdownType == EToolShutdownType::Accept)
	{
		UpdateEditedSkinWeightsMesh();

		// this block bakes the modified DynamicMeshComponent back into the StaticMeshComponent inside an undo transaction
		GetToolManager()->BeginUndoTransaction(LOCTEXT("SkinWeightsPaintTool", "Paint Skin Weights"));

		UE::ToolTarget::CommitMeshDescriptionUpdate(Target, EditedMesh.Get());

		GetToolManager()->EndUndoTransaction();
	}
}


void USkinWeightsPaintTool::UpdateBonePositionInfos(float MinRadius)
{
	const FReferenceSkeleton& RefSkeleton = BoneContainer.GetReferenceSkeleton();
	const TArray<FMeshBoneInfo>& BoneInfos = RefSkeleton.GetRefBoneInfo();
	const TArray<FTransform>& BonePoses = RefSkeleton.GetRefBonePose();

	BonePositionInfos.Reset();

	// Exclude virtual bones.
	for (int BoneIndex = 0; BoneIndex < RefSkeleton.GetRawBoneNum(); BoneIndex++)
	{
		FTransform Xform = BonePoses[BoneIndex];
		int32 ParentBoneIndex = BoneInfos[BoneIndex].ParentIndex;

		while (ParentBoneIndex != INDEX_NONE)
		{
			Xform = Xform * BonePoses[ParentBoneIndex];
			ParentBoneIndex = BoneInfos[ParentBoneIndex].ParentIndex;
		}

		BonePositionInfos.Add({ BoneInfos[BoneIndex].Name, BoneInfos[BoneIndex].ParentIndex, Xform.GetLocation(), -1.0f });
	}

	// Populate the children.
	for (int BoneIndex = 0; BoneIndex < BonePositionInfos.Num(); BoneIndex++)
	{
		FBonePositionInfo& BoneInfo = BonePositionInfos[BoneIndex];
		if (BoneInfo.ParentBoneIndex != INDEX_NONE)
		{
			BonePositionInfos[BoneInfo.ParentBoneIndex].ChildBones.Add(BoneInfo.BoneName, BoneIndex);
		}
	}

	bool bComputedRadius = true;
	while (bComputedRadius)
	{
		bComputedRadius = false;

		for (int BoneIndex = 0; BoneIndex < BonePositionInfos.Num(); BoneIndex++)
		{
			FBonePositionInfo& BoneInfo = BonePositionInfos[BoneIndex];
			if (BoneInfo.Radius > 0.0f)
			{
				continue;
			}

			if (BoneInfo.ParentBoneIndex == INDEX_NONE)
			{
				if (BoneInfo.ChildBones.Num())
				{
					int32 Count = 0;
					float RadiusSum = 0.0f;
					for (const auto& CB : BoneInfo.ChildBones)
					{
						const FBonePositionInfo& ChildBoneInfo = BonePositionInfos[CB.Value];
						if (ChildBoneInfo.Radius > 0.0f)
						{
							RadiusSum += ChildBoneInfo.Radius;
							Count++;
						}
					}
					if (BoneInfo.ChildBones.Num() == Count)
					{
						BoneInfo.Radius = RadiusSum / float(Count);
						bComputedRadius = true;
					}
				}
				else
				{
					// No children either? Take the whole mesh.
					BoneInfo.Radius = EditedMesh->GetBounds().SphereRadius;
				}
			}
			else 
			{
				BoneInfo.Radius = FVector::Dist(BoneInfo.Position, BonePositionInfos[BoneInfo.ParentBoneIndex].Position) / 2.0f;
				bComputedRadius = true;
			}

			if (bComputedRadius)
			{
				BoneInfo.Radius = FMath::Max(BoneInfo.Radius, MinRadius);
			}
		}
	}
}


void USkinWeightsPaintTool::RenderBonePositions(FPrimitiveDrawInterface* PDI)
{
	static const int32 NumSphereSides = 10;
	static const int32 NumConeSides = 4;

	IPrimitiveComponentBackedTarget* TargetComponent = Cast<IPrimitiveComponentBackedTarget>(Target);
	FTransform WorldTransform = TargetComponent->GetWorldTransform();

	for (const FBonePositionInfo& BoneInfo : BonePositionInfos)
	{
		FLinearColor BoneColor;
		FVector Start, End;

		End = BoneInfo.Position;
		End = WorldTransform.TransformPosition(End);

		if (BoneInfo.ParentBoneIndex != INDEX_NONE)
		{
			Start = BonePositionInfos[BoneInfo.ParentBoneIndex].Position;
			Start = WorldTransform.TransformPosition(Start);
			BoneColor = FLinearColor::White;
		}
		else
		{
			// Root bone.
			BoneColor = FLinearColor::Red;
		}
		BoneColor.A = 0.10f;

		if (BoneInfo.BoneName == CurrentBone)
		{
			BoneColor = FLinearColor(1.0f, 0.34f, 0.0f, 0.75f);
		}

		const float BoneLength = (End - Start).Size();
		// clamp by bound, we don't want too long or big
		const float Radius = FMath::Clamp(BoneLength * 0.05f, 0.1f, MaxDrawRadius);

		// Render Sphere for bone end point and a cone between it and its parent.
		DrawWireSphere(PDI, End, BoneColor, Radius, NumSphereSides, SDPG_Foreground, 0.0f, 1.0f);

		if (BoneInfo.ParentBoneIndex != INDEX_NONE)
		{
			// Calc cone size 
			const FVector EndToStart = (Start - End);
			const float ConeLength = EndToStart.Size();
			const float Angle = FMath::RadiansToDegrees(FMath::Atan(Radius / ConeLength));

			TArray<FVector> Verts;
			DrawWireCone(PDI, Verts, FRotationMatrix::MakeFromX(EndToStart) * FTranslationMatrix(End), ConeLength, Angle, NumConeSides, BoneColor, SDPG_Foreground, 0.0f, 1.0f);
		}

		// SkeletalDebugRendering::DrawWireBone(PDI, Start, End, BoneColor, SDPG_Foreground, Radius);
	}
}


void USkinWeightsPaintTool::BeginChange()
{
	ActiveChange = MakeUnique<FMeshSkinWeightsChange>(CurrentBone);
}


TUniquePtr<FMeshSkinWeightsChange> USkinWeightsPaintTool::EndChange()
{
	return MoveTemp(ActiveChange);
}


void USkinWeightsPaintTool::ExternalUpdateValues(const FName& BoneName, const TMap<int32, float>& NewValues)
{
	TArray<float>* SkinWeightValues = SkinWeightsMap.Find(BoneName);
	if (SkinWeightValues == nullptr)
	{
		return;
	}

	for (const auto& IV : NewValues)
	{
		SkinWeightValues->GetData()[IV.Key] = IV.Value;
	}

	if (BoneName == CurrentBone)
		UpdateBoneVisualization();
}


void USkinWeightsPaintTool::InitializeSkinWeights()
{
	const FReferenceSkeleton& RefSkeleton = BoneContainer.GetReferenceSkeleton();

	const FSkeletalMeshConstAttributes MeshAttribs(*EditedMesh);
	const FSkinWeightsVertexAttributesConstRef VertexSkinWeights = MeshAttribs.GetVertexSkinWeights();
	const int32 NumVertices = EditedMesh->Vertices().Num();

	// Create a map of all bones to their per-vertex weights.
	SkinWeightsMap.Reset();
	for (const FMeshBoneInfo& BoneInfo : RefSkeleton.GetRefBoneInfo())
	{
		SkinWeightsMap.Add(BoneInfo.Name, {}).AddZeroed(NumVertices);
	}

	for (int32 VertexIndex = 0; VertexIndex < NumVertices; VertexIndex++)
	{
		const FVertexID VertexID(VertexIndex);

		for (UE::AnimationCore::FBoneWeight BoneWeight: VertexSkinWeights.Get(VertexID))
		{
			FName BoneName = RefSkeleton.GetBoneName(static_cast<int32>(BoneWeight.GetBoneIndex()));
			const float Weight = BoneWeight.GetWeight();

			if (Weight >= MinimumWeightThreshold)
			{
				// If the source mesh has a bone that we don't recognize, we ignore it. It's
				// weight will get cleared when the new weights are updated back to the 
				// source mesh.
				TArray<float>* PerVertexWeights = SkinWeightsMap.Find(BoneName);

				if (PerVertexWeights)
				{
					PerVertexWeights->GetData()[VertexIndex] = Weight;
				}
			}
		}
	}

	// Pick a root bone.
	CurrentBone = RefSkeleton.GetBoneName(0);
	PendingCurrentBone.Reset();
}


void USkinWeightsPaintTool::UpdateEditedSkinWeightsMesh()
{
	using namespace UE::AnimationCore;
	
	FSkeletalMeshAttributes MeshAttribs(*EditedMesh);
	FSkinWeightsVertexAttributesRef VertexSkinWeights = MeshAttribs.GetVertexSkinWeights();
	
	const FReferenceSkeleton& RefSkeleton = BoneContainer.GetReferenceSkeleton();

	TMap<FBoneIndexType, const TArray<float>*> BoneIndexWeightMap;
	for (const auto& BoneNameAndWeights : SkinWeightsMap)
	{
		const int32 BoneIndex = RefSkeleton.FindBoneIndex(BoneNameAndWeights.Key);
		if (BoneIndex != INDEX_NONE)
		{
			BoneIndexWeightMap.Add(static_cast<FBoneIndexType>(BoneIndex), &BoneNameAndWeights.Value);
		}
	}

	FBoneWeightsSettings Settings;
	Settings.SetNormalizeType(EBoneWeightNormalizeType::AboveOne);

	TArray<FBoneWeight> SourceBoneWeights;
	SourceBoneWeights.Reserve(MaxInlineBoneWeightCount);

	const int32 NumVertices = EditedMesh->Vertices().Num();
	for (int32 VertexIndex = 0; VertexIndex < NumVertices; VertexIndex++)
	{
		SourceBoneWeights.Reset();

		for (const auto& BoneIndexWeight : BoneIndexWeightMap)
		{
			SourceBoneWeights.Add(FBoneWeight(BoneIndexWeight.Key, (*BoneIndexWeight.Value)[VertexIndex]));
		}

		VertexSkinWeights.Set(FVertexID(VertexIndex), FBoneWeights::Create(SourceBoneWeights, Settings));
	}
}


USkeleton* USkinWeightsPaintToolProperties::GetSkeleton(bool& bInvalidSkeletonIsError, const IPropertyHandle* PropertyHandle)
{
	bInvalidSkeletonIsError = false;
	return SkeletalMesh ? SkeletalMesh->GetSkeleton() : nullptr;
}


#undef LOCTEXT_NAMESPACE