RangeBlends · Down at the water

The Riverbank

Close enough to see the reeds. Boulders in the channel, bushes on the bank, a footbridge somebody put across — and water that moves. Every one of those is a lookup: the rocks are where the hash says, the bridge is where the seed says, and the current is a function of (x, z, t), so it flows without anything ever being stepped forward.

scene

The water's edge

Drag to walk along the bank. Nothing you see is stored, and nothing is being simulated — the current at any moment is looked up, not stepped.

g = 0 t = 0.00 boulders 0 bushes 0 trees 0 bridge — stored 0 bytes

Moving water without a simulation

A river in a game is usually particles, or a scrolling texture, and either way something has to be updated every frame and kept between frames.

Here the surface shade of a water block is f(x, z, t) — a travelling wave read off the same integer hash as everything else. Nothing accumulates, so pausing costs nothing, scrubbing costs nothing, and two people looking at the same t see the same ripple on the same block.

The glints are the same trick with a sharper threshold, and the reeds lean by a slow wave with a per-plant offset so they do not sway in unison.

Who put the bridge there

Boulders sit where the hash says, but only in water deep enough to hold one — so they cluster where the channel is wide, the way they actually do.

The bridge crosses at a spot chosen from the seed, and it finds its own landing on both banks: the deck is laid at the height of the higher bank and the posts drop to the riverbed, so it fits ground it was never told about.

Bushes and trees thin out with height and keep away from the water line. Every one is a hash at its own coordinate, which is why walking away and back gives you the same bank, plant for plant.

Zoom out: The Ruler Valley →  ·  put your own things in it: The Build Code →

Terrain is valleyGrid, the same ground as every other world here. Props are integer hashes at their own coordinates. The current is a polynomial travelling wave, so it stays on the deterministic path with the rest of the height code — no sin, no cos, nothing that drifts between machines.