I used three things to make this: Geometer’s Sketchpad (to make one black and white version; the whole thing is made of semicircles), MS-Paint (to color the six different versions which appear here), and the website http://www.makeagif.com (to assemble the six separate still images into one .gif file, with the illusion of motion). The surprising thing to me was how fast the process was, once I had the idea of my goal for a finished product.
RobertLovesPi.net 
Thanks for the links. I want to make some gif files, too. Cool colors. Very cool effect!
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Hello Robert…
Another point of view :
I prefered to use original “Geometer’s Sketchpad motion and coloring”…
Of course I refer to your post in the video’s description…
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Thanks for the shout-out! Also, very impressive work! =)
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Hello Κώστας Λαμπρινίδης and Robert,
Both of your “spinning wheels” are very nicely done!
Hi Robert! Do you know why your “wheel” appears to spin clockwise only and not counter clockwise?
Do you know what kind of optical illusion this is? I would like to classify it in my special post published at https://soundeagle.wordpress.com/2017/09/28/optical-illusions/
In the post, I have included a List of Optical Illusions in a very large table. In your opinion, what kind of Optical Illusion(s) listed there is likely to be operating in your illusory “spinning wheel”?
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Hello, SoundEagle. My spinning wheel is made of six still images in a particular order that produces the illusion of clockwise movement. If I had ordered these “slides” the opposite direction, the result would be a spinning-wheel illusion with the apparent movement being counter-clockwise. Other than that, I don’t know how to classify the illusion. It’s the same technique we see all the time with animations of all types.
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