int ellipseOne = 255;
int ellipseTwo = 175;
int ellipseThree = 0;
int ellipseFour = 125;


void setup() {
  size(500,500);
}

void draw() {
  background(100);
  stroke(255);
  line(250,0,250,500);
  line(0,250,500,250);
  noStroke();
  //rectMode(CENTER);
 
  if (mouseX < width/2 && mouseY < height/2) {
    fill(ellipseFour);
    rect(0,0,250,250);
    fill(ellipseOne);
    ellipse(mouseX,mouseY,250,250);
    fill(255,0,0);
    rect(mouseX,mouseY,100,100);
  } else if (mouseX > width/2 && mouseY < height/2){
      fill(ellipseThree);
      rect(250,0,250,250);
      fill(ellipseTwo);
      ellipse(mouseX,mouseY,250,250);
      fill(100,100,200);
      rect(mouseX,mouseY,100,100);
  } else if (mouseX < width/2 && mouseY > height/2){
      fill(ellipseTwo);
      rect(0,250,250,250);
      fill (ellipseThree);
      ellipse(mouseX,mouseY,250,250);
      fill(0,0,255);
      rect(mouseX,mouseY,100,100);
  } else if (mouseX > width/2 && mouseY > height/2){
      fill(ellipseOne);
      rect(250,250,250,250);
      fill (ellipseFour);
      ellipse (mouseX,mouseY,250,250);
      fill(0,255,0);
      rect(mouseX,mouseY,100,100);
  }
}