let yc;

​

function setup() {

  createCanvas(600, 600);

  angleMode(RADIANS);

}

​

function draw() {

  noStroke();

  background(220);

  var diam1 = 400;

  var radius1 = 200;

  circle(width/2, height/2, diam1);

  var mx = map(mouseX, 0, width, -300, 300);

  var my = map(mouseY, 0, height, -300, 300);

  push();

  fill("black");

  translate(width/2, height/2);

  var distance = dist(width/2, height/2, mouseX, mouseY);

  if(distance > 100) {

    xc = mx * (200/distance) - (mx * (100/distance));

    yc = my * (200/distance) - (my * (100/distance));

  } else if(distance < -100) {

    xc = mx * (200/distance) + (mx * (100/distance));

    yc = my * (200/distance) + (my * (100/distance));

  } else {

    xc = mx;

    yc = my;

  }

  circle(xc, yc, 200);

  pop();

}