Epicycles

A chain of epicycles, each of which rotates with constant angular speed, can draw even very complex shapes. Ptolemy (90 – 168 BC) used this idea to model, based on observations, the orbits of the then known planets.

Try drawing something by clicking & dragging in the area below. The drawing must be a single closed curve. For example, it could be some kind of banana; or a star or a potato.

The system of epicycles describes the design. You can adjust the speed by acting on the following two buttons:   + –

You can change the number of circles used by setting a lower limit for the circle radius. The lower this limit is, the better the approximation is: Minimum radius = 0   + –  

You can increase and decrease the zoom level:   + –

This animation is released under an MIT license. The code is here.

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