How do I set particle rotation so it matches their (initial) velocity, i.e. the direction they are emitted or “flying” at?
Here is a PG clarifying:
would like this to be more like “streaks” where each particle points in the direction it’s flying.
You probably need to do this yourself in the update function.
@Joe_Kerr thanks a lot for the example 
It does look like this only take effect after a particle is created, i.e. it spawns with angle = 0.
Also how would this work with GPU particles?