Two Layer-1 generation fixes surfaced by the per-layer atlas viewer:
- Layer1Output now carries grid_w/grid_h (the downsampled working-grid the
positions live in). The client maps overlays from these, so the scale is
correct for any source heightmap resolution rather than assuming the texture
size — fixes overlays projecting at half scale into a corner.
- Drainage basin boundaries are traced as ordered, non-self-crossing contours
via Moore-neighbour tracing instead of an angle-from-centroid sort. The sort
produced star-shaped, self-crossing polygons for concave basins that rendered
as straight chords across the map.
Golden (cascade_layer1.json) and the cross-language atlas_response_ready
fixture regenerated. 100 atlas lib tests + the new tracer test pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
jpmschweitzerandClaude Opus 4.7
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