ReaperOfVeriod
412ef4707b
Revisited an older conclusion and found the numbers were fine but the inference
from them was not.
The claim was: i16[3] in a tie vertex is not a skin/joint index, because vertices
sharing a value are 0.95x FARTHER apart than vertices differing in it.
mean pairwise distance, same slot-3 value 14,481
mean pairwise distance, different slot-3 value 13,795
ratio 0.95x
control: same position-x bucket 8,105
The measurements are correct, and the control shows the test works. What does not
follow is the conclusion. The premise was "vertices sharing a joint sit together",
and that is only true for a TIGHTLY LOCALISED joint. It is false in the cases that
are common:
* a rigid tie object -- a leaf, a banner, a piece of foliage -- puts every vertex
on joint 0, so "vertices sharing a joint" IS the whole mesh and the mean
distance is the mesh's own diameter
* a root or hip bone's influence region can span most of a mesh
* bone weights fall off gradually, so membership is not a spatial partition
A 0.95x ratio is precisely what a rigid object bound to one joint PREDICTS.
Absence of clustering is fully consistent with the joint reading; the test never
had the power to separate them. A negative result I did not expect was reported
as a disproof.
This makes the hypothesis STRONGER, for an independent reason: MobyInstance carries
jointCnt at 0x57 and jointCache at 0x58, so this engine demonstrably has joints and
per-moby joint state. A per-vertex field in 0..=254 is exactly the shape of a
joint index.
What was always established still stands, and is all that was: slot 3 is per vertex
(50 distinct values per packet) and not shared across LODs (75.3% same-class
against a 78.7% control). The LOD result is the one thing arguing against a joint
index, though two LODs binding a rigid mesh identically would produce it without
being informative.
So: not understood, with the joint reading now the LEADING CANDIDATE rather than a
disproved one. Corrected in the format file and the roadmap, including the second
mention added two commits ago.
This is the sixth correction in this session to withdraw a conclusion rather than
sharpen one, and the first where the measurement was sound and only the reading
was wrong -- which is the hardest kind to catch, because the number looks right and
is quoted in the commit message as well as the doc.
Going Commando
A native PC reimplementation of Ratchet & Clank: Going Commando (PlayStation 2, 2003), written in Rust.
The game is reimplemented, not emulated. There is no MIPS interpreter here and no CPU emulator: the systems are ported to Rust so they run as ordinary native code.
Status: initial scaffold. The disc is identified and verified, the
workspace builds, and nothing else is implemented yet. See
docs/roadmap.md for where things stand and what comes next.
The target
| Game | Ratchet & Clank: Going Commando |
| Platform | PlayStation 2 |
| Disc | SCUS_972.68 v1.01, USA Black Label |
| Video | NTSC, 60 Hz |
| Boot ELF SHA-1 | bacda860cbd6723142e86db56f197e47e728970f |
Verified against a real disc — see docs/disc-identification.md.
This is the build the reference projects pin; Greatest Hits v2.00 is a
different binary and is not the target.
No game content
This repository contains no game assets, no disc images, no BIOS dumps and no proprietary toolchains. You supply your own legally obtained copy of the disc as an input, the way the upstream reference projects do.
A pre-commit hook enforces this, blocking disc images, asset directories, container signatures and files over 50 MiB. If you clone elsewhere, enable it:
git config core.hooksPath .githooks
Layout
crates/
gc-formats/ asset format parsers (pure, no I/O beyond the caller's buffer)
gc-extract/ disc pipeline: identify, unpack, verify
gc-game/ game logic: hero, weapons, moby classes, progression, saves
gc-video/ IPU / MPEG-2 decode
gc-engine/ Bevy app: Graphics Synthesizer, VU0/VU1, renderer, frame loop
docs/
disc-identification.md which disc we build against, verified
roadmap.md phases, gates, current status
plan/ one file per subsystem, written as work proceeds
formats/ format specs, written as formats are reversed
tools/
identify-disc.py identify any Going Commando disc image
vendor/
rerac/ pinned upstream reference checkout (not tracked)
Building
Requires a Rust toolchain via rustup.
cargo check --workspace
cargo test --workspace
The host audio backend is disabled in Cargo.toml (see the comment there) so
that the workspace builds without system ALSA development headers. Audio decode
is the last phase of the port and lives in gc-video; re-enable it and install
alsa-lib-devel when that work starts.
Identifying a disc
python3 tools/identify-disc.py <your-disc.iso>
Reports the serial, version and video mode from SYSTEM.CNF, hashes the boot
executable, and warns when the disc is not the supported build. Reads only a
few megabytes, so it is near-instant.
How it will be verified
Visual and behavioural comparison against PCSX2, replaying recorded input and
comparing frames, level by level. The PS2 float model is reproduced rather than
approximated — see AGENTS.md.
PCSX2 is installed and working on this machine; the comparison loop that reads
the game's own memory over its debug protocol is up, and level 0's and level
1's tfrag lighting are verified byte-exact against it. See
docs/plan/pcsx2-verification.md for the
setup and how to run it.
Credits and licensing
This project learns from and is built on the work of others. Licences are
recorded in PROVENANCE.md and notices must travel with any
code derived from them.
- ReRAC — a native Rust/Bevy port of Ratchet & Clank (2002), the first game. ISC. The architecture this project follows.
- OpenRAC / rac2-gc-decomp — matching decompilation research for this game. MIT. Source of verified struct layouts and engine documentation.
- Wrench — community documentation of Insomniac's container formats. GPL, used as a specification reference only; no code is copied.
Ratchet & Clank is a trademark of Sony Interactive Entertainment. This is an unofficial fan project, not affiliated with or endorsed by Sony Interactive Entertainment or Insomniac Games.