This applet demonstrates some of the graphics capabilities of Java by drawing trochoids. Trochoids are the curves drawn by a Spirograph (tm) using the circle template. For those not familiar with this toy, I will describe the trochoid further. If two tangent circles have their center points on the same side of the tangent (i.e., are nested) and the smaller circle is rolled around the larger circle without slipping, then a trochoid (specifically, a hypotrochoid) is traced by the path made a point on a radial spoke of the smaller circle. This applet may take a few seconds to a minute to load. Please be patient.

Too bad you can't see the applet. It is really cool. You need the Java plug-in.

I have completed a user interactive Java drawing program. The settings the user needs are described as follows. First, you may select the color of the trochoid. Next, you select the radius of the smaller circle. You must select an integer between 1 and 150. Then, you select what I call the offset. This is the distance from the center of the smaller circle template that the pen is placed. Note that you can pick an offset that is larger than the radius of the moving template. This, in effect, allows you to draw curves that are simply not possible with the Spirograph (tm). The last field is the number of revolutions the smaller template moves around the larger fixed circle. Usually 10 will suffice, but feel free to experiment. The "Draw" button draws the trochoid according to your specifications. The "Remove" button removes the last trochoid drawn. The "Refresh" button clears all of the trochoids drawn. Have fun!

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Copyright 1997 Cynthia Sadler