morphazoid
A Julia-set contour with a moving boundary playhead.

Press Play to traverse the selected Julia boundary. Arrow keys scrub the boundary. Use the mouse wheel or View zoom control to zoom, and drag empty stage space or Shift-drag to pan. Left turns raise the Basic Shepard pitch by default; right turns lower it. The optional Shepard plus vertical harmony synth adds a quieter voice that maps vertical position from a minor third at the bottom to a perfect fifth at the top.