[Michał Chraper]

So, with little modification, working code looks like that…

spd = effect("speed")("Slider");
x = value[0];
y = value[1];

if (spd == 0) {[x, y]}
else {[x + time*spd, y]}

[Michał Chraper]

Thanks for respond Dan. Reading the article You quoted I understood where is the problem in my expression. I didn’t know that I can’t use “speed” word as variable name. Since I change it to “spd” shortcut expression started to work.

Indeed it’s a bit complicated to control acceleration and deceleration but until you want to control constant speed, e.g. by slider control, it’s easy as my expression 😉