Terrain Mixer

Build “Terrain Mixer,” a procedural landscape generator that runs entirely in the browser. Use a seed plus controls for elevation, roughness, erosion, water level, snow line, and vegetation density. Display a responsive 3D landscape together with a synchronized contour map and a movable cross-section profile.

All three views must update when a control changes. Add Randomize, Reset, a few visually distinct presets, and the ability to copy or save the current seed and settings locally. Animate transitions between terrain states instead of abruptly replacing the geometry. Use procedural noise and lightweight approximations; do not require external terrain data or an API.

Prioritize an attractive creative-tool interface and smooth interaction over scientific realism. Run build and lint, then verify every control, preset, seed, and synchronized view in the browser with no console errors or major performance problems.