[MING-ZCH]

Summary

Adds a realism layer to Code-to-Video: the program stays the source of truth (frames are still pure functions of (t, params), byte-reproducible), but the pixels it composes can now be real footage, path-traced 3D and a camera finish. Targets the categories the painted engine could not reach: real human motion, 3D anthropomorphic characters, physics, visual effects, world knowledge, title sequences and special styles on real pixels. Also turns controllability into data: c2v pairs renders source/target edit pairs with exact masks.

New tools

• c2v assets (lib/assets.mjs): search/fetch from Wikimedia Commons, NASA, Poly Haven (CC0 HDRIs, PBR textures, models), Internet Archive, Pexels/Pixabay (with key), direct URLs (incl. .glb). Licence, author, page and sha256 go to projects/<p>/assets.lock.json (committed); media under assets/ is not. restore re-fetches and refuses changed downloads; --interp=N adds motion-compensated in-betweens (ffmpeg minterpolate) for slow motion; NASA items carry their metadata as facts.
• engine/real.js: footage() (source time under the virtual camera, chroma key, screen/add/lightest/darkest), speedRamp(), handheld(), grade() (tone curve, temperature, bloom, halation, aberration, defocus, grain, letterbox), PROJECT.shutter sub-frame motion blur, PROJECT.look = 'real'; P() edit params from PROJECT.params + ?params=.
• c2v blender (blender/): Python scene files rendered in Cycles (Metal/OptiX/CUDA/HIP) — HDRI, PBR, Bullet rigid bodies (baked, kinematic releases), Mantaflow fire/smoke with blackbody flame colour, ember particles, shadow catcher, glTF characters with NLA-blended actions, material restyling, and an optional measure(ctx) hook whose result (e.g. impact frames) lands in the layer meta for sound sync.
• c2v pairs (lib/pairs.mjs): one target video per param edit next to a shared source, exact difference masks, pairs.jsonl with zh/en instructions and changed-frame stats; sweep samples single-parameter edits from a declared space; --export writes source/target/mask keyframe triplets; --list dry-runs.
• stylize('oil') (Kuwahara + canvas + impasto); macOS Playwright Chromium detection.

Probes (all selftest PASS, check 0 errors)

Project	Categories	Picture
real-motion	human motion · title · text · style	Commons gymnastics footage: title with focus pull, 0.25× motion-interpolated slow motion + push-in, lower third, ink-wash restyle + seal
real-physics	physics · title · 3D	path-traced metal letters released under Bullet gravity; variants: glass, rubber, Moon gravity (fall times match √(2h/g))
real-world	world knowledge	NASA Artemis I launch; mission, date, pad read from the NASA item's metadata; mission clock
real-vfx	visual effects	Mantaflow explosion + embers + rigid debris composited into an 8k HDRI plate with a shadow catcher
real-human	3D anthropomorphic · 3D human	toy robot acting on a desk shot like a macro photo (85 mm f/2); mocap-driven dancer
real-domino	physics	68 Bullet dominoes round a heart built from arcs + tangents, turning red as they fall; clicks at the simulation's own impact frames (22.3 plaques/s)

Edit pairs produced

real-motion 24 (8 hand-written + 16 sampled), real-physics 4, real-human 3, real-domino 1. Masks are local where the edit is local (e.g. title text 0.9 % of the area on 85/240 frames; robot repaint 5.1 % on its 141 frames).

Tests

node tests/run.mjs ALL PASS · node tests/replay.mjs 7/7 historical failures caught · selftest PASS on all six probes.

Limits

• Photoreal scripted humans are not covered: free rigged characters are stylised or toys; needs scanned rigged humans (MPFB/SMPL-X) + mocap retargeting.
• No camera tracking: CG cannot be placed into moving footage.
• Mantaflow fire is improved (blackbody colour, embers) but not film-grade at this resolution.
• Masks use a fixed threshold: subtle global edits (small temperature shifts) are under-masked; use the param diff for global edits.
• Cycles' Metal kernel loader crashed twice when Blender shared the GPU with the Chrome renderer; running Blender alone avoided it (cause not established).
• Rendered media and fetched assets are not committed; c2v assets <p> restore and the c2v blender commands in each lock entry rebuild them.

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