nx_wind_erosion.nx

nx_wind_erosion.nx -- directional anisotropic erosion generator. Fourth demonstration of the kind-specific-generator cardinal `feedback-kind-specific-generators-not-broad-noise`. Previous shipped kind-generators: nx_forest_layout -- scattered features (Poisson-like) nx_river_carve -- polyline path nx_beach_zone -- banded zone This one: nx_wind_erosion -- directional anisotropic vector field Wind doesn't erode terrain uniformly. A south-facing slope under north wind gets MORE scour than a north-facing slope under the same wind. And on the leeward side, blown-particle deposition builds dunes. This primitive captures that anisotropy. Wind-internal logic in v1: - 4 cardinal wind directions (NORTH/EAST/SOUTH/WEST) for an anisotropic dot-product test. Caller supplies LOCAL SLOPE (dh/dx, dh/dz) at the query point. - Windward factor = dot product of wind direction with slope. Positive = facing into the wind (exposed) -> erode. Negative = facing downwind (sheltered) -> deposit dunes. - Two strength params (scour + dune) so caller tunes erosion and deposition independently. V2 follow-ups (queued): - 8 cardinal directions (add NE/SE/SW/NW with diagonal slopes) - Arbitrary wind angle in degrees + sin/cos lookup via nx_camera_q14 - Multi-step wind history (prevailing wind + occasional storms) - Wind speed / strength field varying over space (terrain shadow) - Particle transport modeling (sand grains move from windward to leeward; equilibrium dunes emerge) - Composes with nx_beach_zone v2 dune-barrier model - Composes with nx_weather_pattern for storm-driven episodic events Loss audit: Q14 integer arithmetic; dot product is exact. Signed delta scales the strength params linearly; no information loss beyond Q14 quantisation.