​

​

function setup() {

  createCanvas(400, 400);

  stroke(0);

  strokeWeight(2);

  noFill();

}

​

function draw() {

  background(255);

  rect(50, 50, 150, 150)

  check();

}

​

​

function check() {

  let posx = mouseX;

  let posy = mouseY;

  let w = 5; // check area of pix

  let off = floor(w / 2);

  free = true;

  for (let i = 0; i < w; i++) {

    for (let j = 0; j < w; j++) {

      let x = posx - off + i;             // adjust to middle of area

      let y = posy - off + j;

      let cx = get(x, y);

      if (brightness(cx) < 50) free = false;

      //    console.log("mx "+posx+" my "+posy+" x "+x+" y "+y+ " free "+free);

    }

  }

  console.log("mx " + posx + " my " + posy + " free " + free);

}