public static FbxDouble3 XYZEulerFromQuaternion(Quaternion rotation)
{
// Unity wrappers don't have FbxVector4::SetXYZ(FbxQuaternion) to convert quat -> xyz euler.
// We can abuse FbxAMatrix to do the same thing.
FbxQuaternion fbxQuaternion = new FbxQuaternion(rotation.x, rotation.y, rotation.z, rotation.w);
// We're using the FBX API to do the conversion to XYZ eulers.
var mat = new FbxAMatrix();
mat.SetIdentity();
mat.SetQ(fbxQuaternion);
// "The returned rotation vector is in Euler angle and the rotation order is XYZ."
FbxVector4 v4 = mat.GetR();
return(new FbxDouble3(v4.X, v4.Y, v4.Z));
}