Jeroen, eyeballing the lakes: "they did not seem to run the same coastline
code as ocean does". Correct, in two separate ways.
The coastline warp was ocean-only. invent_primitives displaces the sample
through coast_warp_px before reading the ocean mask, but the lake test read
the UNWARPED position, so ocean coasts got invented bays and capes while lake
shores traced the bare elevation contour. It cannot be fixed by warping the
lake sample alone: a lake is where a filled surface sits above terrain, two
reads that must agree, so moving one and not the other puts water on
hillsides or holes inside lakes. Both surfaces move together in the rung-0.5
pass, or neither does.
And shore morphology was structurally unreachable at a lake edge. Every gate
keyed on ocean_fraction_q, which is always 0 in a lake basin because lakes sit
above sea level. Ruled: lakes get full shore morphology — cliffs, beaches,
deltas. Gates key on proximity to water, not to ocean. No new vocabulary
needed; MorphologyZone already carries Fjord, Delta, Wetland, CliffCoast and
DuneStrand.
The interesting part is what separates the sea-flavoured types, because it
isn't salinity. A delta builds land outward where the river deposits faster
than the water removes; an estuary is the inverse, a drowned valley widening
seaward. The discriminator is tidal energy: the microtidal Mediterranean is
ringed with deltas (Nile, Rhone, Po) despite being salt, while the macrotidal
Atlantic gives estuaries (Thames, Severn, Gironde). So lakes always resolve to
Delta — and so does a tideless sea, which an ocean-vs-lake switch would have
got wrong. Tidal energy governs TidalFlat too, so one derived quantity
replaces two stipulations and no "is it the ocean" branch survives.
Salinity is a property of water, not a landform, and is excluded from
morphology entirely. Derive it from below-sea-level connectivity if gameplay
ever needs it. Parked.
Pair session with Jeroen, 2026-07-26.
Co-Authored-By: Claude <noreply@anthropic.com>
jpmschweitzerandClaude
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