FQuat and vector rotation

Development Programming & Scripting C++
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1

Hi,

I take a look at FQuat source code and I have a question about 2 methods:


FQuat::operator*(const FVector& V) const
FQuat::RotateVector( FVector V ) const

operator* documentation say

but, the source code is not the same but the goal is the same… Does anybody know why?



inline FVector FQuat::operator*( const FVector& V ) const
{
	FQuat VQ(V.X, V.Y, V.Z, 0.f);
	FQuat VT, VR;
	FQuat I = Inverse();
	VectorQuaternionMultiply(&VT, this, &VQ);
	VectorQuaternionMultiply(&VR, &VT, &I);

	return FVector(VR.X, VR.Y, VR.Z);
}

and



FORCEINLINE FVector FQuat::RotateVector( FVector V ) const
{	
	// (q.W*q.W-qv.qv)v + 2(qv.v)qv + 2 q.W (qv x v)

	const FVector qv(X, Y, Z);
	FVector vOut = 2.f * W * (qv ^ V);
	vOut += ((W * W) - (qv | qv)) * V;
	vOut += (2.f * (qv | V)) * qv;

	return vOut;
}

Is it better to used the operator or the method instead? RotateVector is not able to use SSE or other.

Thanks!