void draw() {
 background(0);
 smooth();
 // Oculta o cursor
 noCursor();
 // O retângulo é desenhado a partir do centro
 rectMode(CENTER);
 // O retangulo segue o cursor.
 rect(mouseX, mouseY, width/3, height/3);
 ellipse(mouseX+20, mouseY, width/3, height/3);
 triangle(mouseX-20, mouseY,
            mouseX-20, mouseY+10,
            mouseX + 30, mouseY + 5);
}