Lorenz Attractor

var p, q;

var dt = 0.001;

var zoom = 10;

​

var sig = 10, rho = 28, beta = 8/3;

​

function setup() {

  p = createVector(1,1,1);

  q = createVector(1,1,1);

  createCanvas(windowWidth, windowHeight);

  background(100);

  background(0);

}

​

var pauseAnimation = false;

​

function draw() {

  if (pauseAnimation)

    return;

  fill(0,3);

  noStroke();

  rect(0,0,width,height);

  translate(width/2, height/4);

  // orthogonal rotation

  var v = createVector(mouseX - width/2, mouseY - height/2, 0);

  v.normalize();

  var u = createVector(v.y, -v.x, 1);

  u.normalize();  

  for (let i=0; i<500; i++){

    q.set(p.x, p.y, p.z);

    p.add(sig*(q.y-q.x)*dt, (q.x*(rho-q.z)-q.y)*dt, (q.x*q.y-beta*q.z)*dt);

    var qx = q.dot(v);

    var px = p.dot(v);

    var qy = q.dot(u);

    var py = p.dot(u);

    stroke(255,255,0,50);

    strokeWeight(3);

    line(zoom*qx, zoom*qy, zoom*px, zoom*py);

    stroke(0,255,255);

    strokeWeight(1);

    line(zoom*qx, zoom*qy, zoom*px, zoom*py);

  }

}

​

// ------------------------- interface -------------------------

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function keyPressed(){

  if (key=='s')

    saveCanvas('lorenz','jpg');

  if (key=='c')

    background(0);

  if (key=='p')

    pauseAnimation = !pauseAnimation;

}

​

function mousePressed(){

  background(0);

}

​

function mouseWheel(event){

  zoom *= exp(-event.delta/200);

}