createCanvas(400, 400);

}

​

function draw() {

  background(220);

​

  // change color of ellipse based on mouse position

  // more solid closer to border

  // middle color yields to 125.5 ish

  let brightness = map(mouseX, 0, width, 0, 255);

  fill(brightness);

  ellipse(mouseX, mouseY, 100, 100); // follows mouse position

  console.log(mouseX, brightness); // shows correlation

}

​