func update(screen *ebiten.Image) error {
for i := 0; i < 6; i++ {
screen.DrawRect(2*i, 2*i, 100, 100, color.NRGBA{0x80, 0x80, 0xff, 0x80})
}
screen.DrawFilledRect(10, 10, 100, 100, color.NRGBA{0x80, 0x80, 0xff, 0x80})
screen.DrawFilledRect(20, 20, 100, 100, color.NRGBA{0x80, 0x80, 0xff, 0x80})
screen.DrawLine(130, 0, 140, 100, color.NRGBA{0xff, 0x80, 0x80, 0x80})
screen.DrawLine(140, 0, 150, 100, color.NRGBA{0xff, 0x80, 0x80, 0x80})
shape.DrawEllipse(screen, 0, 0, 200, 200, color.NRGBA{0x80, 0xff, 0x80, 0x80})
//shape.DrawArc(screen, 0, 0, 50, 50, 0, math.Pi/2, color.NRGBA{0xff, 0x80, 0x80, 0x80})
return nil
}