coso di alecs (cdp) completo

void setup() {
     size(400,400);
}
    void draw() {
     background(255);
     stroke(0);
     line(width/2,0,width/2,height);
     line(0,height/2,width,height/2);

// Fill a black color
noStroke();
fill(0);
if (mouseX < width/2 && mouseY < height/2) {
  rect(0,0,width/2, height/2);
} else if (mouseX > width/2 && mouseY < height/2) {
  rect(width/2,0,width,height/2);

} else if (mouseX < width/2 && mouseY > height/2) {
  rect(0,height/2,width/2,height);
} else if (mouseX > width/2 && mouseY > height/2) {
  rect(width/2,height/2,width,height);
}
    }