A roulette is created when a circle (or another curve) rolls on a given, fixed curve without slipping. A point that rotates with the moving circle generates the curve. In addition to trochoids, where a circle rolls on a straight line, roulettes defined by two circles are also analyzed. They can be divided into three types:
In the illustration, the fixed circle is displayed in black and the rolling circle in blue. The marks on the circles are intended to emphasize the rolling movement. If the radii of the two circles are in an integer ratio, the curve (red) is closed.
At the top of the panel, you can choose the type of curve. The ratio of the circle radii can be set using the selection fields below. The slider determines the distance of the generating point from the center of the moving circle. The two buttons are used to reset and start, pause or resume the animation.