arc

color bg = #444444;
float b = 0;

void setup() {
}

void draw() {
  background(bg);

  float pos1 = radians(b);
  float pos2 = radians(b+90);

  arc(width/2, width/2, 50, 50, pos1, pos2);

  gif(90);

  b = b +4;
}