terminator
The line of first light, drawn where it actually falls.
The dawn line is a plane of constant world Z crawling north, and the ground it crosses is craters, rims and boulder fields. So this pass takes each pixel's world position back out of the depth buffer and asks that position which side of the line it is on. The band therefore lies over the terrain instead of floating above it — it bends into every crater and climbs every rim wall — and it costs one fullscreen pass rather than any geometry.
Four zones, cut at the two distances NS.DAWN carries, so the picture
and the rules divide the ground in the same places:
| zone | where | look |
|---|---|---|
| hot | more than hot_behind south of the line | bleached, warm, over-lit |
| warm | the band just south of the line | cinnamon; the copper the cargo lives in |
| dusk | up to cold_ahead north | earthlit indigo, dim |
| cold | beyond that | near-black blue |
light_at here is NS.lightAt transcribed, deliberately unchanged.
Sky pixels carry no world position, so the line never touches them.
amount at 0 leaves the frame exactly as it rendered.
Scoped to this part · feeds back into the world's score.