- optical illusion
A central square can be seen, tinted red, aulthough only the rings are colored.
To
New
# set default screen, pen and turtle values
ResetAll SetScreenSize [400 400] HideTurtle
SetSC Black SetPC Green SetPS 1 PenUp
End
To
Rings
For [Radius 20 60 20] [
SetPC White
rArc
270
:
Radius
SetPC Red
rArc
90
:
Radius
]
End
To
rArc
:
Angle
:
Radius
# clockwise arc drawn relative to turtle heading
Arc
:
Radius
Heading
:
Angle
+Heading Right
:
Angle
End
To
Go
New
SetPW 2
Repeat 4 [
Home Right 45 + RepCount *90
Forward 120 Left 135
Rings
]
End