How to face forwards when going backwards

[jh092]

Sorry, one more thing. I thought I had it working but not quite. How do I know which way a spline is facing? I need to know whether to flip a spline or not,  I had this code but turns out it's not right:

Code:

bool IsSplineForwards(CurvySpline spline)
{
    return spline.GetTangent(0.5f).z > 0;
}

thanks

John