asc_dune

ASCENSION's dune sea, deformed in the mesh's own vertices on the GPU every frame.

One thread per vertex of a 224 × 224 grid over 1400 world units. The height a thread writes is the sum of four terms and a pure function of the clock bus: a transverse dune train with a gentle windward ramp and a steep lee slip face; the migration of that whole train downwind by windAccum × CREST_RATE; the scour that lowers the crests and rounds their ridge exponent as the storm works them; and the tornado's passage, integrated over the 24-sample ground track up to torTrackN as a maxed swept trench with twin berms and radial rake. Nothing persists between dispatches — the deform is a pure function of t, so a held preview frame is identical however many times it is captured and a seek lands on the same desert every time.

The vertex buffer is addressed only through the zeroVertex* accessors, and the normal is recomputed in the same pass from four extra evaluations of the height law rather than from reads of the neighbouring vertices, which within one dispatch would race. It also writes the same height into a heights buffer that the tornado and the storm read so neither has to duplicate this noise.