Vector3 GetBezierPosition(float t)
{
   Vector3 p0 = transformBegin.position;
   Vector3 p1 = p0+transformBegin.forward;
   Vector3 p3 = transformEnd.position;
   Vector3 p2 = p3-transformEnd.back;

   return Mathf.Pow(1f-t,3f)*p0+3f*Mathf.Pow(1f-t,2f)*t*p1+3f*(1f-t)*Mathf.Pow(t,2f)*p2+Mathf.Pow(t,3f)*p3