SkeletonRemapping.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Animation/AnimTypes.h"
 
class USkeleton;
 
struct FSkeletonRemapping
{
    FSkeletonRemapping() = default;
    ENGINE_API FSkeletonRemapping(const USkeleton* InSourceSkeleton, const USkeleton* InTargetSkeleton);
 
    const TWeakObjectPtr<const USkeleton>& GetSourceSkeleton() const { return SourceSkeleton; }
    const TWeakObjectPtr<const USkeleton>& GetTargetSkeleton() const { return TargetSkeleton; }
 
    ENGINE_API void ComposeWith(const FSkeletonRemapping& OtherSkeletonRemapping);
 
    int32 GetTargetSkeletonBoneIndex(int32 SourceSkeletonBoneIndex) const
    {
        return (SourceToTargetBoneIndexes.IsValidIndex(SourceSkeletonBoneIndex))
                   ? SourceToTargetBoneIndexes[SourceSkeletonBoneIndex]
                   : INDEX_NONE;
    }
 
    int32 GetSourceSkeletonBoneIndex(int32 TargetSkeletonBoneIndex) const
    {
        return (TargetToSourceBoneIndexes.IsValidIndex(TargetSkeletonBoneIndex))
                   ? TargetToSourceBoneIndexes[TargetSkeletonBoneIndex]
                   : INDEX_NONE;
    }
 
    FTransform RetargetBoneTransformToTargetSkeleton(int32 TargetSkeletonBoneIndex, const FTransform& SourceTransform) const
    {
        return FTransform(
            RetargetBoneRotationToTargetSkeleton(TargetSkeletonBoneIndex, SourceTransform.GetRotation()),
            RetargetBoneTranslationToTargetSkeleton(TargetSkeletonBoneIndex, SourceTransform.GetTranslation()),
            SourceTransform.GetScale3D());
    }
 
    FVector RetargetBoneTranslationToTargetSkeleton(int32 TargetSkeletonBoneIndex, const FVector& SourceTranslation) const
    {
        // Compute the translation part of FTransform(Q1) * Source * FTransform(Q0)
        const TTuple<FQuat, FQuat>& QQ = RetargetingTable[TargetSkeletonBoneIndex];
        return QQ.Get<0>().RotateVector(SourceTranslation);
    }
 
    FQuat RetargetBoneRotationToTargetSkeleton(int32 TargetSkeletonBoneIndex, const FQuat& SourceRotation) const
    {
        // Compute the rotation part of FTransform(Q1) * Source * FTransform(Q0)
        const TTuple<FQuat, FQuat>& QQ = RetargetingTable[TargetSkeletonBoneIndex];
        return QQ.Get<0>() * SourceRotation * QQ.Get<1>();
    }
 
    FTransform RetargetAdditiveTransformToTargetSkeleton(int32 TargetSkeletonBoneIndex, const FTransform& SourceTransform) const
    {
        return FTransform(
            RetargetAdditiveRotationToTargetSkeleton(TargetSkeletonBoneIndex, SourceTransform.GetRotation()),
            RetargetAdditiveTranslationToTargetSkeleton(TargetSkeletonBoneIndex, SourceTransform.GetTranslation()),
            SourceTransform.GetScale3D());
    }
 
    FVector RetargetAdditiveTranslationToTargetSkeleton(int32 TargetSkeletonBoneIndex, const FVector& SourceTranslation) const
    {
        // Compute the translation part of FTransform(Q0.Inverse) * Source * FTransform(Q0)
        const TTuple<FQuat, FQuat>& QQ = RetargetingTable[TargetSkeletonBoneIndex];
        return QQ.Get<0>().RotateVector(SourceTranslation);
    }
 
    FQuat RetargetAdditiveRotationToTargetSkeleton(int32 TargetSkeletonBoneIndex, const FQuat& SourceRotation) const
    {
        // Compute the rotation part of FTransform(Q0.Inverse) * Source * FTransform(Q0)
        const TTuple<FQuat, FQuat>& QQ = RetargetingTable[TargetSkeletonBoneIndex];
        return QQ.Get<0>() * SourceRotation * QQ.Get<0>().Inverse();
    }
 
    UE_DEPRECATED(5.3, "This function is no longer used")
    ENGINE_API const TArray<SmartName::UID_Type>& GetSourceToTargetCurveMapping() const;
 
    ENGINE_API void RegenerateMapping();
    
    UE_DEPRECATED(5.3, "This function is no longer used")
    void GenerateCurveMapping() {}
 
    bool RequiresReferencePoseRetarget() const
    {
        return RetargetingTable.Num() > 0;
    }
    
    bool IsValid() const
    {
        return SourceSkeleton.IsValid() && TargetSkeleton.IsValid();
    }
 
private:
    ENGINE_API void GenerateMapping();
    
private:
    TWeakObjectPtr<const USkeleton> SourceSkeleton;
    TWeakObjectPtr<const USkeleton> TargetSkeleton;
 
    // Table of target skeleton bone indexes (indexed by source skeleton bone index)
    TArray<int32> SourceToTargetBoneIndexes;
 
    // Table of source skeleton bone indexes (indexed by target skeleton bone index)
    TArray<int32> TargetToSourceBoneIndexes;
 
    // Table of precalculated constants for retargeting from source to target (indexed by target skeleton bone index)
    TArray<TTuple<FQuat, FQuat>> RetargetingTable;
};