OL_KanizsaTriangle

function setup() {
  createCanvas(400, 400);//create  the canvas
}
function draw() {
  translate(200,200)
  strokeWeight(3)
  stroke(0);
  noFill();
  push()
  rotate(PI/6)
  polygon(0,0,100,3)
  pop()
  noStroke()
  fill(0)
  circle(100*cos(-5*PI/6),100*sin(-5*PI/6),50)
  circle(100*cos(-PI/6),100*sin(-PI/6),50)
  circle(100*cos(3*PI/6),100*sin(3*PI/6),50)
  fill(255);
  push()
  rotate(-PI/6)
  polygon(0,0,100,3)
  pop()
  noLoop()
}
function polygon(x, y, radius, npoints) {
  let angle = TWO_PI / npoints;
  beginShape();
  for (let a = 0; a < TWO_PI; a += angle) {
    let sx = x + cos(a) * radius;
    let sy = y + sin(a) * radius;
    vertex(sx, sy);
  }
  endShape(CLOSE);
}