createCanvas(900, 900);

  d = pixelDensity();

  cols = ["#001219","#005f73","#0a9396","#94d2bd","#e9d8a6","#ee9b00","#ca6702","#bb3e03","#ae2012","#9b2226"];

  spot = new Spot(random(width), random(height), random(PI), floor(random(cols.length)));

  background(0);

  fill(255);

  noStroke();

}

​

function draw() {

  loadPixels();

  spot.update()

}

​

class Spot{

  constructor(x, y, dir){

    if(x <= 0 || x >= width || y <= 0 || y >= height){

      this.pos = createVector(random(width), random(height));

    } else {

      this.pos = createVector(x, y);

    }

    this.npos = createVector(x, y);

    this.sp = createVector(1, 0);

    this.test = createVector(0, 0);

    this.testp = 0;

    this.testc = 0;

    this.fail = false;

    this.angle = false;

    this.rad = false;

    this.i = 0;

    this.dir = dir;

    this.c = c;

    this.col = color(cols[this.c])

  }

  update(){

    if(this.pos.x <= 0 || this.pos.x >= width || this.pos.y <= 0 || this.pos.y >= height){

      spot = new Spot(random(width), random(height), random(PI));

    }

    for(this.i = 0; this.i < 100; this.i++){

      this.test = p5.Vector.add(this.pos, this.sp);

      if(this.test.x <= 0 || this.test.x >= width || this.test.y <= 0 || this.test.y >= height){

        spot = new Spot(random(width), random(height), random(PI));

      }

      this.testp = 4 * (d * floor(this.test.y)) * (d * width) + 4 * (d * floor(this.test.x));

      this.testc = pixels[this.testp] + pixels[this.testp + 1] + pixels[this.testp + 2];

      if(this.testc == 0 && this.test.x > 0 && this.test.x < width & this.test.y > 0 && this.test.y < height){

        this.sp.setHeading(this.sp.heading() + PI * 0.01);

        this.rad = false

      } else {

        this.rad = true;

        this.i = 100;

      }

    }

    if(this.rad == true){

      this.testp = 4 * (d * floor(this.pos.y)) * (d * width) + 4 * (d * floor(this.pos.x));

      this.testc = pixels[this.testp] + pixels[this.testp + 1] + pixels[this.testp + 2];

      if(this.testc == 0){

        circle(this.pos.x, this.pos.y, this.sp.mag() * 2 - 1);

      } else {

        spot = new Spot(random(width), random(height), random(PI), floor(random(cols.length)));

      }

      if(this.test.x <= 0 || this.test.x >= width || this.test.y <= 0 || this.test.y >= height){

        this.sp.setHeading(this.sp.heading() + PI + random(-QUARTER_PI, QUARTER_PI));

        this.sp.setMag(this.sp.mag() * 2);

        this.npos = p5.Vector.add(this.pos, this.sp);

        if(this.c < cols.length - 1){ this.c++} else {this.c = 0}

        spot = new Spot(this.npos.x, this.npos.y, this.sp.heading(), this.c);

      } else {

        this.sp.setHeading(this.dir + random(-QUARTER_PI, QUARTER_PI));

        this.sp.setMag(this.sp.mag() * 2);

        this.npos = p5.Vector.add(this.pos, this.sp);

        if(this.c < cols.length - 1){ this.c++} else {this.c = 0}

        spot = new Spot(this.npos.x, this.npos.y, this.sp.heading(), this.c);

      }

    } else {

      this.sp.setMag(this.sp.mag() + 1);

    }

  }

}