# sunlight The sun's light inside the water — the two things a surface pass cannot draw, because neither of them lives on a surface. **The caustic net.** Every pixel's world position is unprojected from depth, the sun ray through it is traced up to the surface plane, and the net is evaluated where that ray crosses. The pattern therefore lies on whatever is standing there at the right scale, and slides correctly across a curved white hull instead of being painted in screen space. **The shafts.** The eye ray is marched from the lens out to whatever it hit, and at each step the same net is sampled where that step's sun ray crosses the surface. Light that got through the surface there is light standing in the water here, so the accumulation is the godray, jittered per pixel so its banding becomes grain. Both fade on the same extinction the medium uses. `strength` is a uniform, and the pass returns on it before touching a texture or a derivative — so for the seventy seconds of DEADLIGHT that have no sun in them it costs one branch.

# sea_surface The underside of the North Atlantic in movement I, on the `water_surface` shader. Opaque and double-sided on purpose: it has to lay depth, because the medium's extinction pass measures every eye ray against the depth buffer and a pixel with nothing in it is filled with four kilometres of water. `sky_color` is what Snell's window shows, `sun_size` / `sun_intensity` / `sun_glare` the sunball inside it, and `wave_gain` how hard the swell tears the window's edge. Worn by the `WaterColumn` entity at x = 2000.

# film The shared constants and the film clock for DEADLIGHT. Every slice of the demo reads this module and nothing restates its numbers. It holds three things: - The timing spine — the 14 shots, their durations and their windows. `Film.SHOTS`, `Film.shotAt(t)`, `Film.window(n)`, `Film.movementAt(t)`. Durations live here and nowhere else. - The world contract — the shared coordinate frame (`Film.WORLD`), the named entities each slice owns (`Film.NAMES`), the submersible's contracted path (`Film.SUB_PATH` / `Film.subPoseAt(t)`), the anchor fallbacks that let the film play while it is still being built (`Film.ANCHORS`), the palette (`Film.PALETTE`) and the water's optics (`Film.WATER`). - The clock — a fixed 1/24 s step advanced once per RENDERED frame by `deadlight.FilmDirector`, never from wall time. 2,256 rendered frames is exactly the 94-second film, every time. ```luau local Film = require("deadlight.film") Film.restart() -- t := 0, every slice resets, playing := true Film.seek(48.0) -- deterministic scrub to a moment Film.status() -- where the film is and who has joined it Film.register("abyss", { -- join from your own component's awake() reset = function() end, tick = function(t, dt) end, shot = function(n, tLocal) end, }) ``` Handlers run inside `pcall`, so one slice erroring cannot stop the film for the others. Registering a name twice replaces its handlers.