ground_density_bake(path, key, version, hash, pngs) cuts each layer's PNG (R the chance a cell keeps one,
G an optional scale) into the terrain's 64 m tiles, one layer decoded and let go at a time, as a bake's
file; ground_density_open(...) reads it - or, when it is missing or stale, a dev build's own copy cut from
the PNGs - a tile at a time into a 256-tile clock, never a layer whole. ground_fill(s, cx, cz, band, g)
places a GroundFill row's instances in a stream chunk: a candidate per cell of the band's step, jittered,
kept when a hash of (layer, chunk, band, cell) falls under the density (times the game's trample,
r3d_on_ground_trample, where the row asks); scale, yaw, seed and wind from the same hash. Nothing calls
it yet: behaviour unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
