original.js

function setup() {
    background(255);
    createCanvas(windowWidth,windowHeight);  
}  

var PY, PX;
var x = [20];
var y = [20];
var segLength = 5;

for(var i=0; i<60; i++) {
    x[i]=1;
    y[i]=1;
}

function segment( x, y,  a) {
    strokeWeight(1);
    stroke(0, 0, 0,50);
    push();
    translate(x, y);
    rotate(a);
    line(0, 0, segLength, 0);
    pop();
}

function dragSegment( i,  xin,  yin) {
    var dx = xin - x[i];
    var dy = yin - y[i];
    var angle = atan2(dy, dx);  
    x[i] = xin - cos(angle) * segLength;
    y[i] = yin - sin(angle) * segLength;
    segment(x[i], y[i], angle);
}

function draw() {
    PX=mouseX;
    PY=mouseY;
    dragSegment(0, PX, PY);
    for(var i=0; i<x.length-1; i++) {
        dragSegment(i+1, x[i], y[i]);
    }
}

/*
 "Smoke Brush" by Laura Valentini
http://www.openprocessing.org/sketch/583697
Licensed under Creative Commons Attribution ShareAlike
https://creativecommons.org/licenses/by-sa/3.0
https://creativecommons.org/licenses/GPL/2.0/
*/