Halftone River

The title is a Chinese saying, 摸着石头过河: you cross the river by feeling for the stones. You don't know the whole route in advance. You find the next foothold, test it, and take the step.

The scene draws only dots. There is no line for the path and no marker for the walker. Everything is a depth map of the riverbed sampled on a halftone grid: big dots are shallow water, small dots are deep. The bed is shallow at both banks and deep in the middle, so the crossing gets harder halfway through.

Each step is a patch of shallow water that grows in under the foot. Landing on it sends a ring outward through the grid, made of nothing but dots swelling and shrinking. The current runs across the crossing, so every foothold slowly drifts downstream as it ages. That one drift term is what makes the pattern read as a river instead of a dot pattern.

The pacing is deliberately uneven: a few quick steps, then a pause. An even beat looked like a metronome, and this is meant to be someone deciding. Older footholds fade out behind the walker, so the path reads as a wake the river closes behind you rather than a permanent trail.

Put your cursor on it and you take over the route. The walker steers toward you one stride at a time, still wandering a little on the way, so you lead and it feels its way over. Let go and it continues crossing on its own from wherever you left it. On a phone, tap a spot and the walker heads there.