const maxIter = 100;

const minval = -1.5;

const maxval = 1.5;

​

var ca = 0;

var cb = 0;

​

var counter = 0; 

​

​

function setup(){

  createCanvas(400, 400, P2D);

  pixelDensity(1);

​

}

​

function draw(){

  background(255);

  cb = 0.7885 * sin(counter);

  ca = 0.7885 * cos(counter);

  loadPixels();

  for (var x = 0; x < width; x++){

    for(var y = 0; y < height; y++){

      var a = map(x, 0, width, minval, maxval);

      var b = map(y, 0, height, minval, maxval);

      var n = 0;

      for (;n < maxIter; n++){

        var nextA = a * a - b * b;

        var nextB = 2 * a * b;

        if (abs(a + b) > 4){

          break;

        }

        a = nextA + ca;

        b = nextB + cb;

      }

      var bright;

      bright = map(n, 0, maxIter, 0, 1);

      bright = map(sqrt(bright), 0, 1, 0, 255);

      if(maxIter == n){

        bright = 0;

      }

      var pos = (x + y * width) * 4;

      pixels[pos + 0] = min(bright - 70, 255);

      pixels[pos + 1] = min(bright - 40, 255);

      pixels[pos + 2] = min(bright - 20, 255);

      pixels[pos + 3] = 255

    }

  }

  updatePixels();

  //ca = 1- 1.618;

  counter += 0.01;

​

​

}

​

​