可见，Recoil只影响一根骨骼

如果两个结合就是，Recoil产生的冲击位移作为Limb的控制点，由控制点带动三根骨骼的移动

IMPLEMENT_CLASS(USkelControlLimbRecoil)
...
/*-----------------------------------------------------------------------------
	USkelControlLimbRecoil
-----------------------------------------------------------------------------*/
FVector2D USkelControlLimbRecoil::GetAim(USkeletalMeshComponent* InSkelComponent)
{
	return Aim;
}

/** Is skeleton currently mirrored */
UBOOL USkelControlLimbRecoil::IsMirrored(USkeletalMeshComponent* InSkelComponent)
{
	return FALSE;
}

// USkelControlBase interface
void USkelControlLimbRecoil::TickSkelControl(FLOAT DeltaSeconds, USkeletalMeshComponent* SkelComp)
{
	bApplyControl = FALSE;

	if( ControlStrength > ZERO_ANIMWEIGHT_THRESH )
	{
		// if willing to play recoil, reset its state
		if( bPlayRecoil != bOldPlayRecoil )
		{
			bPlayRecoil = bOldPlayRecoil;

			Recoil.TimeToGo			= Recoil.TimeDuration;

			// ERS_Random == Start at random position along sine wave, 
			// ERS_Zero == Start at 0
			const FLOAT TWO_PI		= 2.f * (FLOAT)PI;
			Recoil.RotSinOffset.X	= Recoil.RotParams.X == ERS_Random ? appFrand() * TWO_PI : 0.f;
			Recoil.RotSinOffset.Y	= Recoil.RotParams.Y == ERS_Random ? appFrand() * TWO_PI : 0.f;
			Recoil.RotSinOffset.Z	= Recoil.RotParams.Z == ERS_Random ? appFrand() * TWO_PI : 0.f;

			Recoil.LocSinOffset.X	= Recoil.LocParams.X == ERS_Random ? appFrand() * TWO_PI : 0.f;
			Recoil.LocSinOffset.Y	= Recoil.LocParams.Y == ERS_Random ? appFrand() * TWO_PI : 0.f;
			Recoil.LocSinOffset.Z	= Recoil.LocParams.Z == ERS_Random ? appFrand() * TWO_PI : 0.f;

			Recoil.RotOffset		= FRotator(0,0,0);
			Recoil.LocOffset		= FVector(0.f);
		}

		if( Recoil.TimeToGo > DeltaSeconds )
		{
			Recoil.TimeToGo -= DeltaSeconds;

			if( Recoil.TimeToGo > 0.f )
			{
				bApplyControl = TRUE;

				// Smooth fade out
				const FLOAT TimePct			= Clamp<FLOAT>(Recoil.TimeToGo / Recoil.TimeDuration, 0.f, 1.f);
				const FLOAT Alpha			= TimePct*TimePct*(3.f - 2.f*TimePct);
				const FLOAT	AlphaTimesDelta	= Alpha * DeltaSeconds;

				// Recoil Bone Rotation, compute sin wave value for each component
				if( !Recoil.RotAmplitude.IsZero() )
				{
					if( Recoil.RotAmplitude.X != 0.f ) 
					{
						Recoil.RotSinOffset.X	+= AlphaTimesDelta * Recoil.RotFrequency.X;
						Recoil.RotOffset.Pitch	= appTrunc(Alpha * Recoil.RotAmplitude.X * appSin(Recoil.RotSinOffset.X));
					}
					if( Recoil.RotAmplitude.Y != 0.f ) 
					{
						Recoil.RotSinOffset.Y	+= AlphaTimesDelta * Recoil.RotFrequency.Y;
						Recoil.RotOffset.Yaw	= appTrunc(Alpha * Recoil.RotAmplitude.Y * appSin(Recoil.RotSinOffset.Y));
					}
					if( Recoil.RotAmplitude.Z != 0.f ) 
					{
						Recoil.RotSinOffset.Z	+= AlphaTimesDelta * Recoil.RotFrequency.Z;
						Recoil.RotOffset.Roll	= appTrunc(Alpha * Recoil.RotAmplitude.Z * appSin(Recoil.RotSinOffset.Z));
					}
				}

				// Recoil Bone Location, compute sin wave value for each component
				if( !Recoil.LocAmplitude.IsZero() )
				{
					if( Recoil.LocAmplitude.X != 0.f ) 
					{
						Recoil.LocSinOffset.X	+= AlphaTimesDelta * Recoil.LocFrequency.X;
						Recoil.LocOffset.X		= Alpha * Recoil.LocAmplitude.X * appSin(Recoil.LocSinOffset.X);
					}
					if( Recoil.LocAmplitude.Y != 0.f ) 
					{
						Recoil.LocSinOffset.Y	+= AlphaTimesDelta * Recoil.LocFrequency.Y;
						Recoil.LocOffset.Y		= Alpha * Recoil.LocAmplitude.Y * appSin(Recoil.LocSinOffset.Y);
					}
					if( Recoil.LocAmplitude.Z != 0.f ) 
					{
						Recoil.LocSinOffset.Z	+= AlphaTimesDelta * Recoil.LocFrequency.Z;
						Recoil.LocOffset.Z		= Alpha * Recoil.LocAmplitude.Z * appSin(Recoil.LocSinOffset.Z);
					}
				}
			}
		}
	}

	Super::TickSkelControl(DeltaSeconds, SkelComp);
}

void USkelControlLimbRecoil::CalculateNewBoneTransforms(INT BoneIndex, USkeletalMeshComponent* SkelComp, TArray<FBoneAtom>& OutBoneTransforms)
{

	Super::CalculateNewBoneTransforms(BoneIndex, SkelComp, OutBoneTransforms);
}