Random Lines
This expression will move a vertical bar back and forth across the screen randomly.
Create a thin, rectangular solid.
Apply the following expression to the position property:
tMin = .5; //minimum segment duration
tMax = 2; //maximum segment duration
end = 0;
j = 0;
while (time >= end){
j++;
seed_random(j,true);
start = end;
end += random(tMin,tMax);
}
endVal = random()*this_comp.width;
seed_random(j-1,true);
x=random(); //this is a throw-away value
startVal = random()*this_comp.width;
x = ease(time,start,end,startVal,endVal);
[x,position[1]]
tMin and tMax are the minimum and maximum time it takes for the line to make one movement. Adjust them to suit your needs.
Duplicate the solid a bunch of times to generate a lot of motion.