https://docs.godotengine.org/en/stable/tutorials/2d/custom_drawing_in_2d.html
draw_line(touch.start, touch.p, _colorB, 2)
func _draw():
if _alt:
for touch in _touch:
if touch.state:
draw_circle(touch.p, 16, _colorC )
draw_circle(touch.start, 16, _colorA)
draw_line(touch.start, touch.p, _colorB, 2)
draw_arc(touch.start, touch.start.distance_to(touch.p), 0, TAU, 32, _colorC, 2)