Simulates a partial water cycle with parallel double-buffering, directional wind, and elevation-based rain shadows. Returns per-cell moisture as a Float32Array (index = row * map.width + col, values in [0, 1]).
Simulates a partial water cycle with parallel double-buffering, directional wind, and elevation-based rain shadows. Returns per-cell moisture as a Float32Array (index = row * map.width + col, values in [0, 1]).