# Sylpheed Godot

A clean-room Godot 4 port of *Project Sylpheed: Arc of Deception*, starting with
the menu shell: developer splash → intro video → title → main menu → submenus.

**You need your own copy of the game.** Nothing in this repository is game
content. An offline exporter reads the disc you supply and writes an open,
moddable asset tree; the Godot project reads only that tree and never touches a
disc format.

```
  your disc  ──▶  crates/sylpheed-export  ──▶  export/   ──▶  port/  (Godot 4)
                  (Rust; decoders come from      JSON + PNG        reads ONLY
                   sylpheed-formats)             + OGG + OGV       open formats
```

## Why the wall

Two reasons, and the second is the interesting one:

1. Godot cannot read IPFB archives, RATC bundles, T8aD textures, XMA banks or
   WMV video, and it should not learn to.
2. **Modding is a goal of this port.** If the runtime reads the original formats,
   modding means reverse engineering. If it reads JSON and PNG, modding means
   opening a file.

## Where the knowledge comes from

The decoders live in [`sylpheed-formats`][formats], pinned by revision — a
separate project, where the reverse engineering happens. Its
`docs/port/HANDOFF.md` is the contract: what has been decoded, what was measured
off the running game, and what is known to be undecodable. Read it before
assuming a value is on the disc.

[formats]: https://git.mc02.dev/fabi/Syplheed-Reborn

## Layout

| | |
|---|---|
| `crates/sylpheed-export/` | disc → open formats. Regenerates `export/` wholesale |
| `port/` | the Godot 4 project |
| `authored/` | decisions that are **not** on the disc, each with its reason |
| `export/` | generated, gitignored, never hand-edited |
| `tools/` | verification harnesses that hold the port to the reference renderer |
| `docs/` | the mission, the format spec, the agent's loop prompt |

## Verifying

`sylpheed-cli screen render` -- built from the same `sylpheed-formats` revision
the exporter is pinned to -- is the reference renderer. `tools/verify-screen`
draws every exported screen both ways and reports the largest per-channel
difference in the frame:

```
tools/verify-screen              # every screen in the manifest
tools/verify-screen main_menu    # one of them
```

Where the two disagree, one of them is wrong; `docs/DECISIONS.md` says which and
why, rather than tuning the port until the number goes down.

## Status

**P1.** The exporter writes `GP_TITLE`'s twelve screen builds and their sprites,
and the Godot project draws any of them statically at 1280x720 from that tree
alone. `main_menu` matches the reference renderer to within 3/255 on every
channel of every pixel. Next: P2, keyframe animation.