float multx,multy;

void setup() {
  size(300,300);
  ellipseMode(CENTER_DIAMETER);
}

void loop() {
  background(0,0,100);
  multx=mouseX/(float)width+0.1;
  multy=mouseY/(float)height+0.1;
  
  noStroke();
  fill(255);
  ellipse(100,150, 50*multx,50*multx);
  
  fill(100,200,255);
  ellipse(200,150, 50*multy, 50*multy);
  
  stroke(255);
  noFill();
  ellipse(width/2,height/2, 10+190*multx, 10+190*multx);
  ellipse(width/2,height/2, 250*multy,250*multy);
}