Updraft

It opens as a cold, silent, ordered volume of paper lit by one shaft of moonlight. It ends as a hollow chimney of light that has thrown its entire contents into the sky.

The Codex Tower is a single cylindrical archive, 34 m across on the inside and 186 m to the apex of its leaded lantern dome, standing alone on a frozen plain. Twenty-two galleries of oak-and-brass shelving spiral its inner wall. Two million volumes. A black slate reading floor with forty desks and forty small oil lamps. At 02:40 on a dead-calm winter night one of those lamps cracks its glass chimney on Gallery 3, and over ninety-six seconds the fire runs the spiral, drops a gallery ninety metres down the shaft, turns the building into a chimney that makes its own weather, and blows the dome out.

What is here

Everything below is spawned at runtime from film.updraftFilm, which advances its clock exactly 1/24 s per rendered frame — so the film is a pure function of how many frames have been drawn, and two runs are the same film.

• The place — a 186 m stone shaft with four ground-floor doors cut through its 2.5 m wall; 22 annular oak decks on 72 radial joists each, with brass rails on 56 stanchions; 2,482 shelf bays and 238,719 volumes as hardware- instanced populations, each book its own width, height and depth; a lantern dome of 176 glass panes on 32 lead-came ribs, every pane built about its own centre so the blow-out tumbles it about itself; 226 brass reading lamps hung out over the void; 300 volumes and 26 shelf timbers parked as kinematic bodies on Gallery 12 for the collapse.
• The arc of light — eighteen point lights up the tower's axis that ARE the moon in Movement I and ARE the fire in Movement IV, each coloured by its own height; physical atmosphere and height fog whose reference follows the descending smoke ceiling; forty 1800 K practicals; auto-exposure bounded per movement; a lens whose focal length is derived from each shot's own stated field of view; a grade in two halves.
• The inferno — 21 GPU emitters driven at a fixed 1/24 s, a custom WGSL particle integrator that gives the shaft its own weather (chimney lift strongest on the axis, swirl, inward entrainment, wind above the dome), and the hero effect: burning pages as cutout sheets with a ragged hole eating inward from a seed-chosen corner, lit by their own white-hot hem and coloured by their height in the shaft.
• The cut and the mix — fifteen set-ups from a 12 cm macro on a desk to 402 m in the air, 26 spatial sources, and a listener placed on the lens each frame.

The rhyme

Shot 1 is one open folio on Desk 7 in the moon shaft. Shot 12 repeats shot 2's camera position, look target and lens exactly — the two share their three camera tables by reference, so they can never drift apart — and it is a different building. Shot 15 is that same folio, burning, tumbling four hundred metres above the tower.

Known gaps

Movement I and II are the weaker half. Looked at from a distance up the shaft, the twenty-two rings of shelving reach the frame as a featureless gradient however they are lit, which cost the two straight-up-the-shaft set-ups their original framing. Shot 7's long lens across the void reads flat. The lamp macro in shot 4 does not read as a lamp.

The film runs from film.updraftDrive, not from play mode: a Population component draws zero instances in play while drawing correctly in edit (OrigoZero/zero#10511), which would take the entire archive out of every interior frame.