Snakes on a sphere - OpenProcessing

sketch239510
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final float r = 120;
float colorShade;
int N;
Line[] lines;
Boolean displaySphere = true;
PVector rotation = new PVector(0, 0);
PVector rotationSpeed = new PVector(0, 0);
​
void setup() {
  size(400, 400, P3D);
  colorMode(HSB, 1);
  noFill(); 
  initialize();
}
​
void draw() {
  background(0);
  noFill();
  translate(width/2, height/2);
  PVector dm = new PVector(pmouseY - mouseY, pmouseX - mouseX);
  dm.mult(.001);
  rotationSpeed.add(dm);
  
  rotationSpeed.mult(.94);
  
  rotation.add(rotationSpeed);
  rotateX(rotation.x);
  rotateY(rotation.y);
​
  noFill();
  for(int i = 0; i < N; i ++){
    lines[i].display();
  }
  
  if(displaySphere){
      fill(.015, .2, .2);
      noStroke();
      sphere(.99*r);
  }
}
​
void mousePressed(){
  initialize();
}
​
void keyPressed(){
    displaySphere = !displaySphere;
}
​
void initialize(){
  N = ceil(random(15));
  colorShade = random(.9);
  lines = new Line[N];
  for(int i = 0; i < N; i ++){
    lines[i] = new Line();
  }
}
​
class Line {
  int nb = 200;
  PVector root = new PVector(random(123), random(123));
  final float s = random(.02, .06);//.05
  ArrayList<PVector> angles = new ArrayList<PVector>();
  ArrayList<PVector> shift = new ArrayList<PVector>();
  PVector speed = new PVector(random(-s, s), random(-s, s));
  float a = random(123);
  float b = random(123);
  color col = color(random(colorShade, colorShade + .1), random(.7, 1), random(.7, 1));
  final PVector rot = new PVector(random(123), random(123));
​
​
​
  Line() {
    for (int i = 0; i < nb; i ++) {
      root.add(speed);
      //      a += TWO_PI * (noise(root.x) - .5) / 10;
      //      b += TWO_PI * (noise(root.y) - .5) / 10;
      float prevA = a;
      a += 2 * asin(sqrt(map(noise(root.x), .2, .8, 0, 1))) / 30;
      b += PI * map(noise(root.y), .2, .8, -1, 1) / 30;
      //    if (Float.isNaN(a)) a = prevA;
      if (a == NaN) a = prevA;
      angles.add(new PVector(a, b));
      shift.add(new PVector(0, 0, 0));
    }
  }
​
  void display() {
    rotateX(rot.x);
    rotateY(rot.y);
    stroke(col);
    float x, y, z, u, t;
    beginShape();
    for (int i = 0; i < nb; i ++) {
      u = angles.get(i).x += noise(root.x + i/1)/1500;
      t = angles.get(i).y += noise(root.y + i/1)/1500;
      x = r * sin(u) * cos(t);
      y = r * sin(u) * sin(t);
      z = r * cos(u);
      vertex(x, y, z);
    }
    endShape();
​
​
    root.add(speed);
    //    a += TWO_PI * (noise(root.x) - .5) / 10;
    //    b += TWO_PI * (noise(root.y) - .5) / 10;
    float prevA = a;
    a += 2 * asin(sqrt(map(noise(root.x), .2, .8, 0, 1))) / 30;
    b += PI * map(noise(root.y), .2, .8, -1, 1) / 30;
    angles.remove(0);
    shift.remove(0);
    angles.add(new PVector(a, b));
    shift.add(new PVector(0, 0, 0));
    //    if (Float.isNaN(a)) a = prevA;
    if (a == NaN) a = prevA;
  }
}