Erosion

stable

A procedural terrain generator you can watch erode

Erosion is a procedural terrain generator that runs entirely in your browser. It starts the way most terrain demos do, with layered simplex noise, and then it keeps going: a hydraulic erosion simulation traces thousands of water droplets down the slopes, each one picking up sediment where it speeds up and dropping it where it slows down. Drag the erosion slider and a field of random bumps reorganizes itself into river valleys and ridgelines in a couple of seconds, live, with no bake step and no page reload.

Noise you can steer

Seed, octaves, frequency, lacunarity, and persistence are all sliders. Move one and the heightmap regenerates instantly, so you can dial in the base landscape before a single droplet runs.

Erosion that actually simulates

The droplet model tracks position, velocity, water volume, and sediment load per step, and conserves total heightmap mass exactly. The terrain redistributes rather than drifting or blowing up.

Raw WebGL2, no framework

The mesh renders through hand-written WebGL2 with per-vertex normals and an elevation-and-slope color ramp. No three.js, so the whole path from heightmap to pixels stays small and readable.

View the code on GitHub

Questions

Is this a free procedural terrain generator I can use online?
Yes. It runs in the browser with no account, no install, and no upload. The full source is MIT-licensed on GitHub if you want to run or fork it yourself.
How is this different from a Perlin noise terrain demo in WebGL?
Most Perlin or simplex noise terrain demos stop at the noise: a static heightmap with a color ramp. Erosion runs a live hydraulic erosion pass on top of the noise, so you watch water carve the shapes instead of just looking at randomness.
Does it use Perlin noise?
It uses simplex noise, Ken Perlin's faster follow-up to his original Perlin noise algorithm. Both are gradient noise; simplex has fewer directional artifacts, which matters once erosion starts following the slopes.
What is hydraulic erosion?
It is the process of water reshaping land by carrying sediment downhill. The simulation approximates it with many short-lived droplets: each flows along the local gradient, erodes where the slope steepens its flow, and deposits where the slope flattens.
Does it work on a phone?
Yes. Drag one finger to orbit, pinch to zoom, and pull up the bottom sheet for the controls. It needs a browser with WebGL2, which every current mobile browser supports.