Disk Drawing - OpenProcessing

mySketch
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"use strict"
​
let orbitPoints = [];
let circles;
let startTime;
let p;
​
function setup() {
    createCanvas(600, 600);
    createCircles();
    background(255);  
    startTime = millis();
    colorMode(HSB, 100);
}
​
 
​
function draw() {
    let t = ( millis() - startTime )*0.001;
  
    let theta = 0.1*t;
    //Random Archimedean spiral:
    //let r =  random(0.2) + random(0.3) *theta;
    
    let r = 0.5 + 0.1*theta;
    let p = createVector(r*cos(theta),r*sin(theta)) 
    
    if(r < 1.0) {
        orbitPoints = trackedIterativeInversion(p.x,p.y,circles);
    }
    else{
        startTime = millis();
        //background(255);
        noLoop();
        return;
    }
​
  strokeWeight(1);
    noFill();
    stroke(100*r,100,100,10);
  
    for(let k = 0; k < orbitPoints.length-1; k++) {
      
        let p =  orbitPoints[k];
        let q =  orbitPoints[k+1];
​
        let i = 0.5*(p.x + 1)*width;
        let j = 0.5*(p.y + 1)*height;
      
        let i2 = 0.5*(q.x + 1)*width;
        let j2 = 0.5*(q.y + 1)*height;
​
        line(i,j,i2,j2);
  
    } 
}
​
/*
function mouseClicked() {
  startTime = millis();
}
*/
​
function OrthoganalCircle(theta,dTheta) {
  
    let R = 1.0/cos(dTheta);
    this.r = abs(tan(dTheta));
    this.x = R*cos(theta);
    this.y = R*sin(theta);
    
    this.containsPoint = function(p){
        let c = createVector(this.x,this.y);
        return c.dist(p) < this.r;
    };
  
    this.invert = function(p){ 
        let c = createVector(this.x,this.y);
      
        let op = c.dist(p);
      
        let oq = this.r*this.r/op;
        
        let dq = p5.Vector.sub(p,c).normalize().mult(oq);
        
        return p5.Vector.add(c,dq);
    };
}
​
function createCircles() {
  
    const dTheta = 4.4;
  
    let c1 = new OrthoganalCircle(0,dTheta);
    let c2 = new OrthoganalCircle(TWO_PI/3,dTheta);
    let c3 = new OrthoganalCircle(2*TWO_PI/3,dTheta);
​
    circles =  [c1,c2,c3]; 
  
}
​
function trackedIterativeInversion(x,y,circles) {
  
    let flag = true ;
 
    let points = [createVector(x,y)]; 
    const iterations = 10;
  
    for(let i = 0; i<iterations; i++) {
        var k;
        flag = true;
        for ( k in circles ) {
          
            let circle = circles[k];
            let p = points[points.length-1];
            if (circle.containsPoint(p)){
                points.push(circle.invert(p));
                flag = false;
            }
      }
        if (flag) {
            break;
        }
    }
  
    return points;
  
}
​
​
​
/*----------Some little helpers to convert from pixel indecies to disk coordinates ---------------*/
​
function xx(i){
  return  2*i/width - 1;
}
​
function yy(i){
  return   2*i/height -1;
}
​
function ii(x){
  return  0.5*(x +1)*width;
}
​
function jj(y){
  return   0.5*(y +1)*height;
}
​
function indexx(i,j){
  return   4*(i + j*width);
}