public float approximate(Vector3 _in, int near)
{
int n = near;
Vector3 nearest = controlPoints[n];
Vector3 previous = controlPoints[n > 0 ? n - 1 : spanCount - 1];
Vector3 next = controlPoints[(n + 1) % spanCount];
float dstPrev2 = _in.Dst2(previous);
float dstNext2 = _in.Dst2(next);
Vector3 P1, P2, P3;
if (dstNext2 < dstPrev2)
{
P1 = nearest;
P2 = next;
P3 = _in;
}
else
{
P1 = previous;
P2 = nearest;
P3 = _in;
n = n > 0 ? n - 1 : spanCount - 1;
}
float L1Sqr = P1.Dst2(P2);
float L2Sqr = P3.Dst2(P2);
float L3Sqr = P3.Dst2(P1);
var L1 = (float)Math.Sqrt(L1Sqr);
float s = (L2Sqr + L1Sqr - L3Sqr) / (2f * L1);
float u = Mathf.Clamp((L1 - s) / L1, 0f, 1f);
return((n + u) / spanCount);
}
