Paintstormstudio.com

Over from krita there's a brush control variable (what I mean is like pen pressure, direction, tilt, stroke speed, etc) is distance drawn, for example I want to make a brush that runs out of paint after X distance and starts smudging/blending colors around instead.

You can look at how Krita implemented it as an example of how to do it (krita just has a setting of distance in pixels then a bezier curve graph to determine how it behaves during this distance and after), I also think Corel Painter has something like this since it has a brush with this type of behavior.

In Paintstorm I believe you can create this effect using the transition value. I think, ive not played around with something like that.
Armor

I can confirm, it is set in transition, you can adjust the scale value as well as the curve to modify the effect.

Thanks, that is what I was looking for, guess I found the naming of it confusing.