Starts a linear raise by rate/sec from zero when trig input crosses from non-positive to positive.
When rate == 1, Sweep may be used to get a continually-updating measurement of the time (in seconds) since the last trigger.
triggers when trig input crosses from non-positive to positive.
rate/sec raise rate
Sweep can be used as a resettable Phasor or Line - one that can start, pause, resume and stop. To get a resettable XLine behavior change the
linexp in the SynthDef below.