What I was doing, was something like this:
effect(smokeTrailPar, maxv(1, 40 * time_step), my.x, vec_sub(oldPos.x, my.x));
vec_set(oldPos.x, my.x);
It doesn't work with MOVE flag, cause it prevent BEAM from actually being 'smeared' (as the manual said) via 'velocity'.
Some screens to how you what happens:
Without MOVE flag:
With MOVE flag:
So it looks to me, that when I use MOVE flag, BEAM is 'smeared' along the p.vel_x. So it works like initial speed, instead of beam length
vel - Initial speed vector or beam length.
Greets
