Real Time Demo:
The actor has an update build function exposed so it is possible to update them mesh on run-time.
However, as it was not in the scope for this initial release to get it running during run-time, the code may not be optimized well enough and may cause performance hits depending on the complexity of the spline (i.e. number of curves) if you are calling it every tick.
You might get away with the performance drop if you script it to update at certain events only.
This is the blueprint script that was running for the demo:
