# A Door Into Four Seasons — `paper-seasons@1.0.0`

An ivory paper door opens on a layered forest valley where spring, summer, autumn and winter slide past while a tiny copper fox waits on the path. Papercut diorama. Loops.

A small ivory arched door in a paper wall swings open on a valley made of five layers of cut paper. Seasonal sheets fold and slide through in turn, spring blossom, summer green, autumn orange and winter blue-white with drifting snow, while a miniature copper fox waits on the winding path. Lit cut edges and soft occlusion between the layers give it depth. The door closes again at the end, so the 8 seconds loop. The film has no settings.

- Kind: background; status: published; digest sha256:8a6b9cba6dc55b8ca4929d1354445c6c3d78c54a70511bf18d06b4d7deeb1c6b
- Role: Shader film (three.js): Layered papercut diorama, a finished 8-second portrait film with no settings.
- Implementation: three; entry `src/paper-seasons.js`
- Files: https://aipixelwizard.com/registry/paper-seasons/1.0.0/<path> (`LICENSE`, `asset.json`, `demo.js`, `index.html`, `src/paper-seasons.js`)
- Manifest JSON: https://aipixelwizard.com/api/v1/visuals/paper-seasons/versions/1.0.0
- Runnable demo: https://aipixelwizard.com/registry/paper-seasons/1.0.0/index.html (open over http; it imports sibling packages by relative path)
- Dependencies (exact): `three@0.185.1` (source) — Renderer and a full-screen shader material.; `apw-runtime@1.0.0` (demo) — Demo harness.

## Exports
- `createPaperSeasons() => { scene, camera, setSize(width, height), update(time), dispose() }` — The film as one full-screen shader; render its scene with its camera straight to the canvas.

## Composition
- Inputs: The time in seconds, 0 to 8. The film has no other settings.
- Outputs: An opaque full-frame picture, already in display colours: render it straight to the canvas.
- Coordinates: Composed for a 4:5 portrait frame and measured by the frame height: in a wider frame the picture stays centred at full height and its background fills the sides; in a narrower one, such as 9:16, the sides are cropped.
- Lighting: Soft studio light, with lit cut edges and occlusion between the paper layers.
- Timing: The door opens, the four seasonal sheets fold and slide through in turn, then the door closes.
- Works with: —
- Five parallax forest layers move at different speeds.
- Petals and snow are cut-paper shapes, not particles.
- Every pixel is a function of the time alone, so frames can be rendered in any order.

## Output and loop
- 1080×1350, 30 fps, 8 s, procedural
- Seamless loop: yes — Every part of the film is a function of the time modulo its length, and every motion completes whole cycles, so the last frame meets the first.
- Verified 2026-10-10 in Chrome 154.0.8037.97 headless on Linux 7.0.0-38-generic (x64), Node 22.14.0 (WebGL 2 via SwiftShader (software)); deterministic: yes; loop check: Frame 0 vs end state (progress 1): mean |Δ| 0.0000, max |Δ| 0 of 255.

## Use it
New project: Create a WebGLRenderer on a canvas (no antialiasing), call createPaperSeasons() once and film.setSize(width, height); then for each frame call film.update(timeInSeconds) and renderer.render(film.scene, film.camera).

Existing project: Copy src/paper-seasons.js, which needs only three. Render film.scene with film.camera into your own canvas or render target; the output is opaque and already in display colours, so use no tone mapping or colour conversion.

Reuse ideas:
- Seasonal greeting: the four seasons pass in turn while the door stands open.
- Seamless loop: the door closes at the end, so it repeats cleanly.
- Doorway transition: the closed door at each end is a clean place to cut.

## Limitations
- The film is finished: it has no settings. To change colours or timing, edit the shader.
- It is composed for a 4:5 portrait frame.
- Its length is fixed at 8 seconds; repeat the loop to fill a longer clip.

## License
MIT. Copyright (c) 2026 AI Pixel Wizard. Released under the MIT License. See LICENSE in this folder.

Provenance: From the owner's collection Twenty Impossible Worlds: the original GLSL ES 3.00 shader of the film “A Door Into Four Seasons”, created with ChatGPT / Codex and used as published, wrapped for AI Pixel Wizard as a three.js full-screen shader in October 2026. The collection's synthesised soundtrack is not part of this ingredient.