# Roadmap Status as of **2026-10-11**. A from-scratch native Rust reimplementation of Ratchet & Clank: Going Commando (PS2). Each phase ends in a **gate** — something checkable, not a feeling that it is going well. Phases are ordered so that the riskiest unknowns are retired early, while they are still cheap to retire. ## Where we are - [x] Target disc identified and verified (`SCUS_972.68` v1.01, NTSC 60 Hz) - [x] Workspace builds (`cargo check --workspace`) - [x] Repository hygiene in place (pre-commit guard, `.gitignore`, licence record) - [x] **Phase 1 complete.** The disc pipeline runs end to end and is verified against a committed hash table, every one of the 92 asset containers parsing. The pipeline now also writes each level's chunk descriptors where they exist (3 of 27 levels). - [x] **Phase 2 in progress.** Level containers are parsed through their typed header, and the `data` extent is parsed as a container of byte ranges. The geometry decompresses: level 0 yields 16,969,296 bytes of level content from a 9.7 MB stream. - [x] **Parsers with real-disc tests, per asset type.** `level_wad`, `data`, `core_index` class tables, `tfrag` (format, topology, textures, LOD, normals, colour), `occlusion`, `sky`, `moby`, `collision` framing and header, `shrub` (blob, packets, palette, billboard), the post-shrub `chunks` container, `sound_bank` framing and `level_overlay`. 227 tests green against the real disc. **What is open is naming, not locating** -- see the Phase 2 list for the four types that still have no decoded fields: `tie` vertices, collision cells, `SBlk` records, `volumes` and `moby_anim`. - [x] **Lighting verified against the running game.** PCSX2 2.8.2 with savestates for level 0 and level 1. The tfrag lighting pass is byte-exact on both against the game's own RAM. Setup and method in `plan/pcsx2-verification.md`. - [x] **First drawable frame.** `gc-engine` loads a level, applies LOD selection and morphing for the camera, groups triangles by texture and draws them under a Bevy fly-camera. Level 0 renders as 26,758 textured triangles across 92 textures with correct UVs. Set `GC_ENGINE_SHOT=` to capture a frame and exit. - [ ] **The origin bug this exposed.** Positions are i16 offsets from a per-patch origin, so taking the wrong STROW collapsed the whole level to a +-32 unit blob at the world origin while every parser test still passed: the vertex count matched, the triangle count matched, only the *place* was wrong. Fixed by taking the STROW immediately preceding the first position unpack rather than the last one. - [x] **Per-vertex colour.** The tfrag's RGBA array now modulates the texture, drawn unlit so the frame shows real albedo rather than a faked lighting model. Verified against the stored values (level 0 patch 0 runs `(25,26,26)` to `(108,144,141)`), which are genuinely dark. - [x] **Tfrag normals.** The 256-entry sine table is decoded from the level overlay and normals are built per vertex and handed to the renderer. The overlay has **no ELF header**, so the table cannot be reached through a program header, and its offset differs per level (level 0 `0xb650c`, level 5 `0xcca30`); it is located by matching the whole 256-entry curve. Normals are negated as stored and get the same axis swap as positions. The pipeline now also writes `overlay.bin`. - [x] **The PS2 float model.** `gc-engine::ps2` is the EE's FPU on raw bits: no denormals, no NaN or infinity, truncation toward zero, the adder's operand alignment, and `rsqrt` as sqrt-then-divide. `MAX` reads back in Rust as NaN, which is the sharpest available statement of why this is not `f32`. - [x] **The `LightTfrags` pass** is written and unit-tested against the PS2 model: PEXT5 base colour, `select` set blending, re-normalised blended directions, and `base + A*max(dA, dA*wA) + B*max(dB, dB*wB)`. - [x] **The level light bank parses and level 0 is fully lit.** `gameplay` is a WAD stream; the extractor had been writing it compressed, which is why the bank framing found garbage. All 80,274 vertices of level 0 now go through `LightTfrags`. The renderer still counts and reports how many vertices it lit, because a silent fallback to stored colours would look plausible and be wrong. - [x] **The shrub region is bounded, and with it the whole lump.** Shrub's end was the last unlocated region bound: it is the start of the post-class chunk container, found by a marker-paired signature in `core_data` (the index carries no successor offset). The container closes shrub on the 24 shrub levels and tie on the three without. All 358 shrub class bodies are now bounded and are whole 8-byte records, so shrub measurements are trustworthy for the first time -- the "3.5M records" figure from the unbounded final span is replaced by a measured 9,600. - [x] **Lighting *magnitudes* are verified** by the PCSX2 comparison loop. `gc-trace compare-tfrag-light` runs the pass over level 0's disc data and diffs it against the game's own lit colours in EE RAM (live over PINE, or from a savestate): **all 162,400 colour bytes match**, across 833/833 headers relocated and the light bank byte-identical. Two bugs it found: the normal's z was not negated (dark but plausible, 95.88% agreement), and records with no light set drew transparent black instead of the base colour. See `docs/plan/pcsx2-verification.md`. - [ ] Then the GS register set and the guard-band clip test. The disc being the exact build the reference projects pin is the single biggest favourable fact so far: no disc conversion, no regional timing work, and no re-derivation of the reference baseline. --- ## Phase 0 — Foundation ✅ **Done.** - Disc identified: `SCUS_972.68` v1.01, USA Black Label, NTSC 60 Hz. Boot ELF SHA-1 `bacda860cbd6723142e86db56f197e47e728970f`, entry `0x00131AE8` — the entry point independently matches the value recorded by `rac2-gc-decomp`, which cross-confirms the identification. - `tools/identify-disc.py` reproduces the identification against any disc image and distinguishes a truncated dump from a non-PS2 image. - Five-crate workspace scaffolding, Bevy 0.19.1 pinned, builds clean. - `.githooks/pre-commit` blocks game data. Verified against seven cases: `.iso`, renamed disc image, WAD container, ADX container, `extracted/`, a 60 MiB file, and legitimate source. - `AGENTS.md` and `PROVENANCE.md` record conventions and licences. ### Open from this phase - `alsa-lib-devel` is not installed, so Bevy's host audio backend is disabled in `Cargo.toml`. Audio is the last phase; revisit then. - Bevy feature set is deliberately minimal. Re-add features as needed rather than switching `default-features` back on wholesale. --- ## Phase 1 — Disc pipeline ✅ **Done.** Gate met: every extracted file matches the committed hash table. - [x] `iso9660` reader (R&C2 lists assets as real files, unlike R&C1) - [x] `G/*.WAD` container header parsing — 92 containers, three table shapes - [x] WAD LZ77 decompression (`wad.rs`, four packet classes) - [x] Unpack every container, bounds-checking each extent - [x] SHA-1 table for all 5,135 files (hashes only, never content) - [x] `verify` stage, plus integration tests against a real disc - [x] Format specs written: `disc-layout.md`, `global-wad.md`, `wad.md` - [x] Work record with the negative results: `plan/disc-pipeline.md` ```text gc-extract identify disc.iso -> SCUS_972.68 v1.01 NTSC, ELF SHA-1 matches gc-extract unpack disc.iso out/ -> 5135 files, 4,500,106,960 bytes, 10.8s gc-extract verify out/ table.tsv -> OK: 5135 files match ``` **Not done, deliberately:** the table of contents at sector 1001 is documented but not read. Enumerating the ISO filesystem is simpler and sufficient; the ToC matters when per-level overlay loading is understood in Phase 3. **Two wrong turns are recorded** in `plan/disc-pipeline.md`, because both would be easy to repeat: the container pair table read backwards, and the LZ77 stream mistaken for a bit stream. Both produced plausible-looking wrong output before failing, which is the failure mode worth guarding against. --- ## Phase 2 — Format parsers **Goal:** every asset type parses into plain Rust values, tested against real disc data. Phase 1 hands over the extents; this phase works out what each one contains. **Done so far:** - [x] `level_wad.rs` — the 0x60-byte header on all 27 level containers, naming four extents plus three chunk descriptors. Verified: extents tile each container in file order (27 of 27). - [x] Two facts the format documentation does not state, both measured here: sizes in this header are **sector counts** where the generic `G/` table uses byte counts, and **`LEVEL21.WAD` reports level id 30**, so container order is not level identity. **In progress:** - [x] `data` — the extent header locates `core_index` and `core_data`; the geometry decompresses and is verified on level 0. - [x] `core_index` class tables — moby, tie and shrub. They were ruled out for want of an entry size, which is knowable exactly: each table ends precisely where the next begins, and that chain closes on 27 of 27 levels. 32 bytes per moby/tie entry, 48 per shrub. Across the disc: **5,796 moby, 1,864 tie, 358 shrub classes**. Identifying `tfrag` by its own structure is what led here. - [x] `occlusion` and `sky` offsets located and their first bytes read. - [x] Region layout of `core_data` established: tfrag, occlusion, sky, collision and `textures_base` are offsets, strictly increasing on all 27 levels. Terrain is `[0, occlusion)` and carries inline texels. - [x] Region layout **closed**: the chunk container's marker-paired signature ends the last class region, and the constant trailer ends the container. Every byte of level-specific `core_data` now belongs to a named region. - [x] **tfrag vertex format: recovered.** The tfrags block header gives a table offset (`0x40`) and a patch count; each patch is a 0x40-byte header whose `data` offset is relative to the table, not to the block. Positions are V3_16 payloads inside a VIF1 command list, split across three lists per patch (common, LOD 0+1, LOD 0). The whole vector format is encoded in the command byte and every element size follows from it. Verified on all 27 levels: **18,102 patches, 821,439 vertices**, each patch yielding exactly its own `vert_count`. See `plan/level-assets.md` and `gc-formats::tfrag`. - [x] **tfrag topology: recovered.** Vertex-info (UVs plus LOD parenting), the strip command lists and the index arrays, classified by unpack format and destination VU address. Strip indices address the vertex-info array rather than positions. Every patch's strips expand to exactly its own `tri_count`: **18,102 patches, 809,879 triangles**, all indices in range. See `plan/level-assets.md` and `gc-formats::tfrag`. - [x] **tfrag texture bindings and per-vertex data.** The ad-gifs decode to a texture index, wrap modes, minification filter and LOD bias; the level index gained a texture table (`level_core.rs`) for those indices to land in. Per-vertex RGBA and light/normal records recovered from their fixed offsets. All 27 levels: 47,950 ad-gifs, every index in range, 90% of the level texture tables referenced. - [x] **Level textures decode.** 8-bit indexed texels plus a 256-entry CSM1 CLUT from `gs_ram`, honouring the PS2 CLUT block swap and the 0x80 alpha scale. The pipeline now writes `gs_ram.bin`, which it had been skipping. All 1,595 tfrag textures on all 27 levels decode; 96.8% fully opaque and 96.3% with real detail. Verified visually via the new `gc-extract dump-texture`, because a wrong lookup still yields a well-formed image of the wrong thing. - [x] **tfrag LOD selection.** Switch distances scale as `[6L, 4L, 2L]` from the block header's float; six draw modes result from testing the bounding sphere against `trunc(D * 1024)`, so a patch straddling a threshold takes the coarser mode and distance never moves back to finer detail. Morph weights run 0..1 across each tier's band, and collapse replaces an entry with its first parent rather than blending it. - [x] **tfrag parent indices.** The four V4_8 arrays are classified by VU address, but the addresses collide, and each V4_8 element holds four indices so an array is `count * 4` bytes rather than `count`. With `unk_06`/`unk_0a` suppressing absent tiers, all 370,349 LOD entries across the 27 levels resolve: 29,043 LOD-01 and 341,306 LOD-0, zero failures. See `plan/level-assets.md` for the two corrections. - [x] `gameplay` — **it is a WAD stream**, exactly like `core_data`; the extractor was writing it compressed. Decompressed, level 0 is 1,872,256 bytes and holds 5 directional light sets. The earlier "does not decode with the WAD LZ77 decoder, bit order and header length ruled out" note was wrong about the cause: the decoder was right and the input was not what it looked like. Corrected in `plan/level-assets.md`. - [~] `sound_bank` — container framing parsed (`SoundBankHeader::parse`, `parse_sound_bank`); `SBlk` and `DAW` bounds verified on 27/27. The **record fields inside `SBlk` are not decoded**, and `DAW` shows no detectable stride, consistent with ADPCM. See the note under `level_overlay` below for what the game's own strings say about loading. - [x] `data` — **not geometry.** It is the level's file descriptor: its first table carries the exact byte lengths of `overlay.bin`, `core_index.bin` and `gs_ram.bin` at fixed `u32` indices 1, 3 and 5 on every level checked. What follows the descriptor is still unknown. - [x] `tfrag` — **complete on the disc side.** Vertex format, topology, strips (`TfragStrip`), texture bindings, per-vertex colour and normals, LOD selection, parent indices, morphing and collapse. 36 format tests, 9 texture tests, 23 engine tests. The morphing is a blend toward the **parent vertices'** midpoint, not toward separate morph targets — there are no morph targets in this format, which is what the old "morph targets unrecovered" note wrongly implied. - [x] The tfrag **table record has exactly two relocated pointer fields**, at `+0x10` and `+0x38`, verified against PCSX2 across all **833** records: the loader adds the **table's** RAM address (`0x848040` = block base plus `table_offset`, matching `TfragHeader::data`'s own "relative to the table") to `+0x10`; every other byte of every record is verbatim, and 1,665 fields differ where 1,666 were possible. They are the existing `TfragHeader::data` and `::cube_ofs` -- what RAM adds is that both are **pointers**, not plain offsets. All **833** patches parse, carrying **43,613** vertex-info entries; **499 of 833** have at least one morphing entry. - [x] Behind those pointers, **every patch's bytes are rewritten** -- and it is **not morphing**. Across all 833 patches: the 334 with **no** morphing entries differ by a median **7.80%**, the 499 with morphing entries by **8.12%**, and **0 of 833** are byte-identical to disc. Morphing does not predict which bytes change. Nor is it a relocation: the differences fall in short structured runs with no common `u32` addend. The loader regenerates each patch's **VU packet stream for the LOD tier it selected**, which happens to every patch regardless of morphing. - [ ] What tfrag is **not** yet verified is that the morph matches `resolve_vertex`'s formula. Reading a weight back out of RAM does **not** work -- the positions live inside regenerated VU packets, so there is no stable per-vertex correspondence. The LOD switch distances, morph weight and collapse edge remain derived from the data (tiers classified from the four V4_8 parent arrays, weight running zero to one across each band); verifying them needs the **camera distance at the savestate** so the weight can be computed and compared against the rendered result. - [x] `tie` — **fully chained.** `resolve_tie_class` walks both indirections: the class table is in `core_index.bin`, and the entry's `offset_in_asset_wad` addresses `core_data.bin` (not `core_data.wad`). All **1,864** tie classes resolve with `o_class` agreeing on every one. A `packets` word of **zero means no block at that LOD** -- 2,177 real blocks, 1,551 absent slots. - [x] Tie **blocks are self-delimiting**: `parse_tie_block` walks to the `0xf6` terminator that every real block carries (2,177 of 2,177), followed by zero padding. This is what makes blocks parseable at all -- `packets[1]` bounds one on only 461 of 1,864 classes. - [x] The tie **16-byte record is R&C1's `TiePacketHeader`.** Identified not by resemblance but by R&C1's own rule, `bfc_distance == 5 * shader_count`, holding on **15,219 of 15,219** records across all 2,177 blocks. A block is `[16-byte header][record table][vertex payload]`, and the header word at `+0x00` is the byte offset from the block start to the payload. The earlier "variable-length, not 16-byte records" reading was wrong: the word is not an element count, which is why dividing the payload by it gave 0 of 922. - [x] The tie **vertex element is 16 bytes**, measured over 95,612 vertices on levels 0-2 and settled by comparison: a 12-bit-fixed texcoord hit rate of **82.5%** at 16 bytes against 47.8% at 8 and 44.8% at 12. - [x] The tie **texcoord field is located**: `i16[4]`/`i16[5]` of the 16-byte element, scoring 73.6% for 12-bit fixedness over 36,501 level-0 vertices, against 1.1% for `(0,1)` and 4.8% for `(2,3)`. The `(6,7)` pair scores *higher* at 76.6% and is **not** a texcoord -- it is the near-constant `4096, 0` pair, which is trivially two multiples of 4,096. - [x] `i16[3]` **selects the texcoord encoding**, and it is specifically the **high byte**. Grouped across 95,612 vertices on levels 0-2: high byte `0x00` covers 89,341 vertices (93.4%) at 92% 12-bit fixed, while **every** other high byte scores 0%. The split is on the byte, not the value -- `i16[3]` of 1 and of 771 differ only in the high byte and behave completely differently. Within the all-zero case, `i16[3] == 0` exactly (5,851) is a third distribution at 62%. Three cases: `0x00/0x00`, `0x00/1..255`, and non-zero high byte. - [ ] The remaining tie vertex **fields are not named.** `i16[0..3]` span the full `i16` range with 10,803-13,421 distinct values each. `i16[0..2]` are most likely position, but that is not established. - [~] `shrub` — class table done (48-byte entries, not 32; reading shrub at 32 still gives 231 sane-looking entries of 358, which is the hazard). Geometry header parsed and checked field by field on all 358 spans: `+0x24` equals the entry's own `o_class`, `+0x2c` is an in-span data offset, `+0x16`/`+0x18` are zero, and `+0x1c` names a billboard on exactly the 25 classes whose core-index entry carries billboard texture fields. Shrub does **not** use moby's part-table format. The body is a **24-entry palette of unit-length s16 normals** (squared length within 65,535 of 32767² on all 8,592 entries — a random triple would miss by a billion) plus zero padding records; the billboard record carries K, MMIN and the TEX0/MIPTBP addresses as R&C1's does. What remains open: the three floats in the billboard record, `size`, `mode_bits`, `count`, and **where the mesh geometry lives** — R&C1 puts the mesh packets in this blob and R&C2's blob holds only the palette. - [x] **The tie LOD block is a table of 16-byte records.** The header's word at `+0x00` is the byte offset from the block start to the vertex payload -- the record table's length -- not a count, which is why the payload never divides by it. Each record is a leading `u32` pointer **relative to the table start** plus twelve verbatim field bytes, relocated at load to `table + word`. - [x] **The record is R&C1's `TiePacketHeader`.** R&C1's own rule `bfc_distance == 5 * shader_count` holds on **all 15,219 records of all 2,177 blocks on all 27 levels**. R&C1's rule for the colour offset holds on **none** of them, so the games use that field differently. - [x] **The tie relocation verifies on two levels.** `gc-trace verify-tie-records` checks it against PCSX2's RAM: **87 of 87** blocks on level 0 and **104 of 104** on level 1, zero mismatches, which is what makes the record layout a finding rather than a reading of one block. - [x] **The shrub mesh geometry is in the class blob.** A packet table at `+0x40` names `count` packets between the table and the palette, and they tile on **358 of 358 spans** (2,239 packets), which makes `count` the packet count. Confirmed against the running game, which relocates the table's offsets to absolute addresses and `data_offset` likewise. - [x] `moby` — per-class model geometry. A class span opens with a `u32` pointing at a part table of 16-byte records; parts tile exactly, with `vertex_offset + 16 * vertex_count == next_part` holding for **43,467 of 43,467** parts across every class on all 27 levels. That identity is what makes the record size fall out of the data rather than being assumed. 1,270,802 vertices over 4,560 class spans; 116 spans carry no geometry. Vertices are 16-byte VIF-packed half-float quads, handed back raw. - [ ] `moby_anim` — **still open, and the obvious reading is ruled out.** An instance table would have to scale with the level's moby class count, but **per-chunk-type record counts are level-independent** -- the same types report 90, 77, 50 and 47 on every level tried, and the largest type totals 2,430 = 90 x 27. Nothing in the chunk set is keyed by moby class. The types also pair up (two types both reporting 90 on every level, another pair both 77), which looks like two views of one fixed table rather than two independent tables. - [x] `collision` — container framing and header fields. A 0x40-byte header self-describes: it carries its own size and the payload size, and `header + payload` stays inside `core_data` on all 27 levels. 41,481,520 payload bytes across 19 levels; 8 declare zero length. Header bytes `+8` reads zero on 22 levels and a large value on 7/9/12/13/14; the payload's two leading `u16` are non-zero on all 19 non-empty levels (1-74 and 13-112) and are reported as `CollisionHeader::first`/`::second`. - [ ] The collision **cell layout is not decoded.** The payload does not walk as fixed-stride cells. On level 4 a table starts at payload `+5932` and runs **17 entries** -- deltas rise then fall -- against a 75-cell grid, with no arithmetic relating the two. A 64-byte RAM stride looked promising and is **disproved** -- the longest such run is 27 records of identity matrices, one per level. - [x] **The collision payload is essentially verbatim in RAM, not reshaped.** Level 0's sits at RAM `0xac6800` for a disc address of `0x27e800`: **903,212 of 903,248 bytes identical**, first difference at `+0xdc82c`, with **6** bytes differing in the final 36. Asserted by a savestate-gated test that compares the whole payload. This **overturns** the earlier claim that the grid dimensions are absent from RAM: level 0's `11 x 33` are the first two bytes of that block. The earlier negative came from searching for the dimensions as a `u32` pair when they are two `u16`s -- a bad pattern, not a property of the data. The payload contains ascending `u32` offset tables from `+1024` onward, and disc-side decoding is no longer blocked on reshaping. See `plan/pcsx2-verification.md`. - [x] `occlusion` — the PVS grid. A z/y/x tree of u16 node offsets over 4x4x4-unit cells, populated cells naming 128-byte masks. **412,521 cells over 140,939 masks** across the 24 levels that have one; the mask array ends within 48 bytes of the block boundary on every level. 3 carry no occlusion data, and an offset of 0 means *absent* rather than "at the start" — the latter parses as a grid whose mask array happens to fit, which is how it nearly went wrong. - [x] `sky` — 149 sub-objects across all 27 levels, each with a count, a four-float bounding sphere and texture dimensions. The offset table at `+0x20` is self-limiting: entries run while strictly inside the region. **The word at `+0x0c` is not a count** -- it disagrees with the table on most levels and reads 196,617 on level 2 against 4 sub-objects. - [ ] `volumes` — **not located.** Nothing examined so far presents itself as a volume: `core_data`, the chunk region and `gameplay.bin` all yield structures that are accounted for by something else. - [~] `level_overlay` — header, constant block and level data parsed (`gc_formats::overlay`, 27/27). `+0x10..+0x1220` -- 4,624 bytes -- is byte-identical on every level; the word at `+0x0c` is **not** the file length, falling below it on 17 levels and above on 10. The debug string pool it opens with carries `Camera_CollPrimTest WARNING! - grid out of bounds! (RAR)`, independent support for reading the collision payload's two leading `u16`s as grid dimensions. **The header words are not named and the level-specific tail is not structured yet**; the Phase 3 seven-section parser and relocation are untouched. The seven sections are now named (`.lit .bss .data vtbl camvtbl sndvtbl .text`) and `overlay.bin` is the `.lit` section, whose `+0x00` load base is `0x1A7C80`. - [x] **The post-shrub chunk container.** A 16-byte header, a 10-byte zero gap, then offsets tagged `0xF0000000 | low24` resolving to `chunk_start + low`; header byte 14 is the record count, equal to `offsets.len()` on 1,123 of 1,123 chunks across all 27 levels. **77 distinct chunk types, 1,509 chunks, 34,491 records.** Moby class IDs enrich at 9,493 hits against 246.1 expected with contiguous per-type arrays -- but the arrays land in a different place for each type, so no single pooled scan finds them. - [x] **Chunk record framing is closed.** Every chunk has a **uniform record length** (1,509 of 1,509) -- length varies *between* chunks of a type, never within one, which withdrew an earlier "variable-length type" claim that had been pooled across chunks. The record's leading byte is a **per-chunk phase counter** (`bucket_rule`, 1,262 of 1,509 chunks) and on **1,235** of them *both* leading bytes encode the record's own index in mixed radix (`index_rule`), so the leading bytes carry no per-record information. - [x] **The loader's transformation, from PCSX2 RAM.** Disc offsets `0xf0000000 | low24` are rewritten in RAM to absolute EE pointers `0xf1850000 | low24` -- tag replaced by the chunk's load base, low 24 bits untouched. The payload itself is copied **verbatim**. The index finding is corroborated live: the byte at `+2` takes exactly `0, 16, ... 240`, the 16 values `index_rule` predicts. - [x] **Corrected: a record starts two bytes before the table's offset.** The `02 00` read in RAM as a loader-inserted prefix is the record's own leading word, already on the disc at every record. The loaded table simply points two bytes earlier than the disc's, at that word. It is a field: uniform across a chunk's records on **1,439 of 1,509** chunks, fixed within **all 71 types**, values `{1, 2, 4, 6, 8, 10}`. Disproved readings: an entry count (57 distinct fractional "sizes") and a distinct-leading-byte count (0 of 1,506 agree). - [ ] The chunk **record fields are not decoded**, and no type is named. The body is dense (74% of `f32` reads plausible against a 49% random control) with an index-like tail -- 12 of 163 `u16` slots in the largest type stay below `0x1000` -- but **no count field** exists in the first 64 body bytes at any width or stride tried. Only **9.4%** of `u16` slots are per-chunk constant, so records are not templates. - [x] **Moby class arrays are contiguous per type, and the pooled scan was wrong.** See rule 3a in `AGENTS.md`: the original claim of a `u16` array at slots 129-140 was the largest-stride type dominating an aggregate. Per type, every one of the 26 places its array somewhere else. **Gate:** every parser has a golden test against bytes from the real disc, and reports mismatched header counts as failures rather than warnings. **Discipline:** bound every read. Typed errors, no panics, no reads past the buffer. --- ## Phase 3 — Overlay system **Goal:** make 27 level overlays tractable. Every overlay carries the same seven sections (`.lit`, `.bss`, `.data`, `lvl.vtbl`, `lvl.camvtbl`, `lvl.sndvtbl`, `.text`) and the same engine code, linked at different addresses. ReRAC solves this by masking relocations — `j`/ `jal` targets, `lui` immediates of main-RAM addresses, the `%lo` that completes them, and `$gp`-relative operands — then matching the masked words to find a reference function's copy on another overlay. - [ ] Port the masking and code-identity logic - [ ] `Relocation::func` and `Relocation::data` - [x] `$gp` for this game (`0x001AEFF0`, against R&C1's `0x166c00`) -- confirmed by `OpenRAC/rac2-gc-decomp` `docs/LEVELS.md` for all 27 levels - [ ] Extend the level table from 19 to 27 **Gate:** every level-01 function's relocated copy is found on all 27 overlays; cross-checked against an independent cluster hash. **Why this is high-value:** it turns "27 overlays of unknown code" into a table lookup, and it is the main thing inherited from ReRAC. --- ## Phase 4 — Engine core **Goal:** draw a frame. - [ ] Graphics Synthesizer in wgpu, with the GS's own rules: its `round(log2(z/n) + K)` mip selection, blend and alpha-test behaviour, alpha `0x80` meaning 1.0, CLAMP wrap - [ ] VU0/VU1 skinning and lighting on the PS2 float model - [ ] LOD/morph/cull per `TfragProc` and `TieProc` - [ ] Occlusion culling, fog, shadows - [ ] GIF/VIF packet stream interpretation **Gate:** CPU and GPU paths agree on every vertex of a reference level — the same identity check ReRAC runs. **Risk:** VU1 microcode is **binary** in the game's `.vutext` section, so it is reverse engineered rather than parsed. This is the hardest single item in the project and the main threat to the timeline. Note that ReRAC's own moby VU1 analysis trips their disassembler on two opcodes. --- ## Phase 5 — Veldin vertical slice **Goal:** one planet, playable start to finish. - [ ] Ratchet's controller on a **spherical** planet - [ ] Chargeboots: hold/release timing, chained jumps, dash - [ ] Wrench and the camera - [ ] Collision and the HUD **Gate:** Veldin is completable and visually matches PCSX2 frame-for-frame under replayed input. **This is the go/no-go for the project.** If Veldin works, the other 26 levels are content. If it does not, the reason is discovered while it is still cheap. Spherical gravity is the thing most likely to break, because it invalidates R&C1's movement and camera assumptions wholesale. --- ## Phase 6 — Remaining overlays and the shell - [ ] Per-level moby class dispatch via `lvl.vtbl` - [ ] Remaining 26 levels - [ ] Planets, travel, the Gadgetron vendor, RPG upgrades - [ ] Weapon modification bitmasks (lock-on, shock, acid, …) - [ ] Minigames and challenges - [ ] The 25-state memory-card FSM and its UI - [ ] IFF chunk saves, including import of a R&C1 save to unlock legacy weapons --- ## Phase 7 — Audio and video - [ ] 989snd v2 audio decode and playback (not CRI ADX — a different codec) - [ ] SPU2 mixing, reverb zones, level sounds - [ ] IPU/MPEG-2 video for the title screen and cutscenes --- ## Phase 8 — Fidelity pass Differential testing against PCSX2 across every level: - [ ] Recorded-input frame comparison, per planet - [ ] Geometry, fog, blend, alpha, texture sampling - [ ] Audio sync and 60 Hz timing - [ ] Behavioural comparison: traversal routes, boss timing, RNG --- ## Principles - **A gate is pass/fail, not a percentage.** "Looks fine" is not progress. - **Negative results are written down.** A ruled-out approach saves the next attempt as much as a working one. - **The float model is not negotiable.** Approximate is not the same as faithful, and the difference is visible in how the game feels. - **Fidelity over tidiness.** Where the original does something that looks like a bug, reproduce it and say why in a comment. See `AGENTS.md`.