Roll - Aftereffects Expression

roll.js

numsegments = Math.max(2, Math.floor(effect("Segments")("Slider")));
totallength = Math.max(0.001, effect("Line Length")("Slider"));
seglength = totallength / numsegments;
sepdist = Math.max(0.001, effect("Seperation Distance")("Slider") * 0.5) / (Math.PI * 2);
roll = clamp(effect("Roll")("Slider"), 0, 1);

pos = [0, 0];
cv = [];

firsttheta = Math.sqrt(numsegments * seglength / sepdist);
f = numsegments;
for(i=0; i<numsegments; i++)
{
	u = (i - 1) / numsegments;
	u = linear(u, roll, 1, 0, numsegments);
	f -= clamp(u, 0, 1);
        
	theta = Math.sqrt(f * seglength / sepdist);
	theta -= firsttheta;
        
	if(i != 0)
	{
		x = Math.cos(theta) * seglength;
       		y = Math.sin(theta) * seglength;
		pos += [x, y];
	}
	cv.push(pos);
}

createPath(cv, [], [], false);