phi =0

def setup():
    fullScreen(P2D)
    frameRate(50)
    textAlign(CENTER, CENTER)


def draw():
    stroke(0)

    global phi
    phi += 0.001
    centers = [(width/2, height/2), \
               (width/2 + 250*cos(phi)*(sqrt(2)-1)/(sqrt(2)+1), \
                height/2 + 250*sin(phi)*(sqrt(2)-1)/(sqrt(2)+1))]

    background(100)
    fill(200)
    ellipse(width/2, height/2, 500, 500)
    fill(150)
    arc(width/2 + cos(phi)*250, height/2 + sin(phi)*250, \
        500*sqrt(2), 500*sqrt(2),PI+ phi-QUARTER_PI,PI+ phi+QUARTER_PI, PIE)
    fill(200)
    ellipse(centers[1][0], centers[1][1], \
            500*sqrt(2)/(sqrt(2)+1),500*sqrt(2)/(sqrt(2)+1))
    fill(150)
    arc(centers[1][0] + cos(2*phi)*250*sqrt(2)/(sqrt(2)+1), \
        centers[1][1] + sin(2*phi)*250*sqrt(2)/(sqrt(2)+1), \
        500*sqrt(2)/(sqrt(2)+1)*sqrt(2), 500*sqrt(2)/(sqrt(2)+1)*sqrt(2), \
        PI+2*phi - QUARTER_PI, PI+2*phi+QUARTER_PI, PIE)
    stroke(200, 0, 0)
    line(centers[1][0], centers[1][1], \
         width/2+ cos(phi)*250, height/2 + sin(phi)*250)
    line(centers[1][0] + cos(2*phi)*250*sqrt(2)/(sqrt(2)+1), \
         centers[1][1] + sin(2*phi)*250*sqrt(2)/(sqrt(2)+1), \
         centers[1][0], \
         centers[1][1])
    noFill();
    arc(centers[1][0], centers[1][1], 60, 60, phi, phi+(phi)%(TWO_PI));
    fill(200, 0, 0)
    text("phi", centers[1][0] + 20*cos((phi%TWO_PI)/2+phi),
         centers[1][1] + 20*sin((phi%TWO_PI)/2+phi))
    stroke(0,0,200)
    noFill()
    arc(centers[0][0], centers[0][1], 60, 60, 0, phi%TWO_PI)
    fill(0, 0, 200)
    text("phi", centers[0][0] + 20*cos((phi%TWO_PI)/2),\
         centers[0][1] + 20*sin((phi%TWO_PI)/2))
    line(centers[0][0], centers[0][1], centers[0][0]+250, centers[0][1])
    line(centers[0][0],centers[0][1], \
         width/2 + cos(phi)*250, height/2 + sin(phi)*250)