See the gallery of examples . Harmonograms are mathematically the sums of several harmonic motions in the x and y directions, decayed over time. If another harmonic motion is added to each axis, and they are all in a specific phase relationship, then spirographs can be generated. Simply move the sliders around, and try the check boxes. Amplitude controls the lobe sizes.
Phase controls lobe orientations.
Spiro gangs the x and y amplitude and frequency controls, and sets the phases for symmetric spirographs. Decay makes the curve spiral inwards. Color sets a black background, and draws the picture in color. Thick draws a thick line. This also slows the drawing speed.