Field A — 2D fluid (Navier-Stokes): velocity magnitude as brightness,
hue encodes direction.
Field B — instantaneous rotation centers: for every pair of cells
the center of
rotation is computed and its angular velocity accumulated. Orange = counter-clockwise, blue = clockwise.
Drag on Field A to inject impulses. Double-click on Field B to inject a pattern.
Click or drag on Field B to set a focus circle — Field B then shows only that region; click again or Escape to clear.