ReaperOfVeriod
85fa9d1432
The core header field at 0x08 is zero on all 27 levels, and the seven offsets 0x0c, 0x10, 0x14, 0x60, 0x64 and 0x68 are strictly increasing on every level. Reading them as a sequence of region boundaries gives the layout of core_data: tfrag [0, occlusion) occlusion [occlusion, sky) sky [sky, collision) collision [collision, textures_base) So tfrag = 0 is a real value rather than a missing field, and the terrain is the first 2.12 MB of level 0's geometry. The terrain begins with a short header followed by a repeating 64-byte record from 0x40. Established about those records: byte columns 3, 7, 11 and 15 are 0x48 in every record, which are high bytes of four s16 values giving a near-fixed Y on a planet of radius about 2,187; columns 16 and 17 increase steadily across records like a grid walk; and columns 48-51 carry a repeating ffff00ff pattern characteristic of GS packet headers. The record layout itself is not yet recovered, and the write-up says so rather than guessing. Ruled out and recorded: uncompressed f32 vertices (the longest plausible float run in 16.9 MB is a run of zeros in the collision block, so vertices are packed); GS packet tags at every position (0xE0..0xEF is frequent but uniform, which is what packed data looks like); and a 48-byte record stride (the pattern repeats at 64). Also confirmed this session: the core header base is offset 0 with certainty, because the compressed and decompressed sizes of core_data appear at the same offsets (0x88 and 0x8c) in all 27 levels' core_index. And the occlusion block at the header's 0x0c offset reads as an ascending u16 array of 65 values before restarting, consistent with per-cell visibility records. No code change: this is the reverse-engineering record for the next parser. 75 unit tests, clippy clean.
243 lines
10 KiB
Markdown
243 lines
10 KiB
Markdown
# Roadmap
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Status as of **2026-10-09**.
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A from-scratch native Rust reimplementation of Ratchet & Clank: Going Commando
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(PS2). Each phase ends in a **gate** — something checkable, not a feeling that
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it is going well. Phases are ordered so that the riskiest unknowns are retired
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early, while they are still cheap to retire.
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## Where we are
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- [x] Target disc identified and verified (`SCUS_972.68` v1.01, NTSC 60 Hz)
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- [x] Workspace builds (`cargo check --workspace`)
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- [x] Repository hygiene in place (pre-commit guard, `.gitignore`, licence
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record)
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- [x] **Phase 1 complete.** The disc pipeline runs end to end and is verified
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against a committed hash table: 5,135 files, 4,500,106,960 bytes, every
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one of the 92 asset containers parsing.
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- [x] **Phase 2 in progress.** Level containers are parsed through their typed
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header, and the `data` extent is parsed as a container of byte ranges. The
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geometry decompresses: level 0 yields 16,969,296 bytes of level content
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from a 9.7 MB stream.
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- [ ] Next: the geometry directory's class tables, then `tfrag` terrain.
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The disc being the exact build the reference projects pin is the single
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biggest favourable fact so far: no disc conversion, no regional timing work,
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and no re-derivation of the reference baseline.
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---
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## Phase 0 — Foundation ✅
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**Done.**
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- Disc identified: `SCUS_972.68` v1.01, USA Black Label, NTSC 60 Hz. Boot ELF
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SHA-1 `bacda860cbd6723142e86db56f197e47e728970f`, entry `0x00131AE8` — the
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entry point independently matches the value recorded by `rac2-gc-decomp`,
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which cross-confirms the identification.
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- `tools/identify-disc.py` reproduces the identification against any disc image
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and distinguishes a truncated dump from a non-PS2 image.
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- Five-crate workspace scaffolding, Bevy 0.19.1 pinned, builds clean.
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- `.githooks/pre-commit` blocks game data. Verified against seven cases:
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`.iso`, renamed disc image, WAD container, ADX container, `extracted/`,
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a 60 MiB file, and legitimate source.
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- `AGENTS.md` and `PROVENANCE.md` record conventions and licences.
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### Open from this phase
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- `alsa-lib-devel` is not installed, so Bevy's host audio backend is disabled in
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`Cargo.toml`. Audio is the last phase; revisit then.
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- Bevy feature set is deliberately minimal. Re-add features as needed rather
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than switching `default-features` back on wholesale.
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---
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## Phase 1 — Disc pipeline ✅
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**Done.** Gate met: every extracted file matches the committed hash table.
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- [x] `iso9660` reader (R&C2 lists assets as real files, unlike R&C1)
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- [x] `G/*.WAD` container header parsing — 92 containers, three table shapes
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- [x] WAD LZ77 decompression (`wad.rs`, four packet classes)
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- [x] Unpack every container, bounds-checking each extent
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- [x] SHA-1 table for all 5,135 files (hashes only, never content)
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- [x] `verify` stage, plus integration tests against a real disc
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- [x] Format specs written: `disc-layout.md`, `global-wad.md`, `wad.md`
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- [x] Work record with the negative results: `plan/disc-pipeline.md`
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```text
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gc-extract identify disc.iso -> SCUS_972.68 v1.01 NTSC, ELF SHA-1 matches
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gc-extract unpack disc.iso out/ -> 5135 files, 4,500,106,960 bytes, 10.8s
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gc-extract verify out/ table.tsv -> OK: 5135 files match
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```
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**Not done, deliberately:** the table of contents at sector 1001 is documented
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but not read. Enumerating the ISO filesystem is simpler and sufficient; the ToC
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matters when per-level overlay loading is understood in Phase 3.
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**Two wrong turns are recorded** in `plan/disc-pipeline.md`, because both would
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be easy to repeat: the container pair table read backwards, and the LZ77 stream
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mistaken for a bit stream. Both produced plausible-looking wrong output before
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failing, which is the failure mode worth guarding against.
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---
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## Phase 2 — Format parsers
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**Goal:** every asset type parses into plain Rust values, tested against real
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disc data.
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Phase 1 hands over the extents; this phase works out what each one contains.
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**Done so far:**
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- [x] `level_wad.rs` — the 0x60-byte header on all 27 level containers, naming
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four extents plus three chunk descriptors. Verified: extents tile each
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container in file order (27 of 27).
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- [x] Two facts the format documentation does not state, both measured here:
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sizes in this header are **sector counts** where the generic `G/` table
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uses byte counts, and **`LEVEL21.WAD` reports level id 30**, so container
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order is not level identity.
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**In progress:**
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- [x] `data` — the extent header locates `core_index` and `core_data`; the
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geometry decompresses and is verified on level 0.
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- [ ] `core_index` class tables — the header base is confirmed (the compressed
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and decompressed sizes of `core_data` sit at the same offsets in all 27
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levels), and every offset lands inside `core_data`. But the class-table
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fields do not decode under any field order or stride tried. Ruled out and
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written up in `plan/level-assets.md`. Next: identify `tfrag` by its own
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structure instead of through the header.
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- [x] `occlusion` and `sky` offsets located and their first bytes read.
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- [ ] `gameplay` — begins `WAD` + a per-level byte, and does *not* decode with
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the WAD LZ77 decoder. All 27 levels fail identically, so the input is
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wrong rather than the decoder. Ruled out: bit order, header length, the
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LZ77 framing. Hypotheses queued in `plan/level-assets.md`.
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- [ ] `occlusion` — 2 to 25 sectors, small enough to read whole.
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- [ ] `sound_bank` — `SBlk` and `DAW` signatures found in all 27.
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- [ ] `data` — the large one: 4.2 to 21.9 MB of geometry per level.
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- [ ] `tfrag` — terrain: LOD chains, strips, morph targets
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- [ ] `tie` — instanced environment geometry, fat vertices
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- [ ] `shrub` — foliage and decorative meshes
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- [ ] `moby` — dynamic actors; `moby_anim` — skeletal animation
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- [ ] `collision` — cells, packed vertices, faces
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- [ ] `occlusion` — the PVS grid
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- [ ] `sky`, `volumes`, `textures` (CSM1 CLUT + PS2 alpha)
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- [ ] `level_overlay` — the seven-section parser and relocation from Phase 3
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**Gate:** every parser has a golden test against bytes from the real disc, and
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reports mismatched header counts as failures rather than warnings.
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**Discipline:** bound every read. Typed errors, no panics, no reads past the
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buffer.
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---
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## Phase 3 — Overlay system
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**Goal:** make 27 level overlays tractable.
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Every overlay carries the same seven sections (`.lit`, `.bss`, `.data`,
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`lvl.vtbl`, `lvl.camvtbl`, `lvl.sndvtbl`, `.text`) and the same engine code,
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linked at different addresses. ReRAC solves this by masking relocations — `j`/
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`jal` targets, `lui` immediates of main-RAM addresses, the `%lo` that completes
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them, and `$gp`-relative operands — then matching the masked words to find a
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reference function's copy on another overlay.
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- [ ] Port the masking and code-identity logic
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- [ ] `Relocation::func` and `Relocation::data`
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- [ ] `$gp` for this game (`0x001AEFF0`, against R&C1's `0x166c00`)
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- [ ] Extend the level table from 19 to 27
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**Gate:** every level-01 function's relocated copy is found on all 27 overlays;
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cross-checked against an independent cluster hash.
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**Why this is high-value:** it turns "27 overlays of unknown code" into a table
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lookup, and it is the main thing inherited from ReRAC.
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---
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## Phase 4 — Engine core
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**Goal:** draw a frame.
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- [ ] Graphics Synthesizer in wgpu, with the GS's own rules: its
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`round(log2(z/n) + K)` mip selection, blend and alpha-test behaviour,
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alpha `0x80` meaning 1.0, CLAMP wrap
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- [ ] VU0/VU1 skinning and lighting on the PS2 float model
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- [ ] LOD/morph/cull per `TfragProc` and `TieProc`
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- [ ] Occlusion culling, fog, shadows
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- [ ] GIF/VIF packet stream interpretation
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**Gate:** CPU and GPU paths agree on every vertex of a reference level — the
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same identity check ReRAC runs.
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**Risk:** VU1 microcode is **binary** in the game's `.vutext` section, so it is
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reverse engineered rather than parsed. This is the hardest single item in the
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project and the main threat to the timeline. Note that ReRAC's own moby VU1
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analysis trips their disassembler on two opcodes.
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---
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## Phase 5 — Veldin vertical slice
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**Goal:** one planet, playable start to finish.
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- [ ] Ratchet's controller on a **spherical** planet
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- [ ] Chargeboots: hold/release timing, chained jumps, dash
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- [ ] Wrench and the camera
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- [ ] Collision and the HUD
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**Gate:** Veldin is completable and visually matches PCSX2 frame-for-frame under
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replayed input.
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**This is the go/no-go for the project.** If Veldin works, the other 26 levels
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are content. If it does not, the reason is discovered while it is still cheap.
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Spherical gravity is the thing most likely to break, because it invalidates
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R&C1's movement and camera assumptions wholesale.
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---
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## Phase 6 — Remaining overlays and the shell
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- [ ] Per-level moby class dispatch via `lvl.vtbl`
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- [ ] Remaining 26 levels
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- [ ] Planets, travel, the Gadgetron vendor, RPG upgrades
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- [ ] Weapon modification bitmasks (lock-on, shock, acid, …)
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- [ ] Minigames and challenges
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- [ ] The 25-state memory-card FSM and its UI
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- [ ] IFF chunk saves, including import of a R&C1 save to unlock legacy weapons
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---
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## Phase 7 — Audio and video
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- [ ] 989snd v2 audio decode and playback (not CRI ADX — a different codec)
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- [ ] SPU2 mixing, reverb zones, level sounds
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- [ ] IPU/MPEG-2 video for the title screen and cutscenes
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---
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## Phase 8 — Fidelity pass
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Differential testing against PCSX2 across every level:
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- [ ] Recorded-input frame comparison, per planet
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- [ ] Geometry, fog, blend, alpha, texture sampling
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- [ ] Audio sync and 60 Hz timing
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- [ ] Behavioural comparison: traversal routes, boss timing, RNG
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---
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## Principles
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- **A gate is pass/fail, not a percentage.** "Looks fine" is not progress.
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- **Negative results are written down.** A ruled-out approach saves the next
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attempt as much as a working one.
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- **The float model is not negotiable.** Approximate is not the same as
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faithful, and the difference is visible in how the game feels.
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- **Fidelity over tidiness.** Where the original does something that looks like
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a bug, reproduce it and say why in a comment. See `AGENTS.md`. |