ReaperOfVeriod
a02f79a6d1
Sets up the foundation for reimplementing the PS2 game in Rust rather than emulating it. Nothing is implemented yet; this is the scaffold, the verified target and the working agreements that keep a long project coherent. Target disc, verified against a real image: SCUS_972.68 v1.01, USA Black Label, NTSC 60 Hz boot ELF 2,618,684 bytes, SHA-1 bacda860...d098a77, entry 0x00131AE8 The entry point independently matches the value recorded by the rac2-gc-decomp community reference, which cross-confirms the identification. This is the exact build the upstream research pins; Greatest Hits v2.00 is a different binary and is not the target. NTSC matters beyond label compatibility: PAL discs run 50 Hz, which would make chargeboots and other speed-sensitive movement run at 5/6 speed. Verifying the disc before writing movement code avoids discovering that in Phase 5. Contents: - Five-crate workspace (formats, extract, game, video, engine) on Bevy 0.19.1, matching the version ReRAC uses so its Graphics Synthesizer and VU work stays portable. `cargo check --workspace` is clean. - tools/identify-disc.py, which reproduces the identification against any disc image and distinguishes a truncated dump from a non-PS2 image. - .githooks/pre-commit, refusing game data from entering git history: disc image extensions, asset directories, container signatures at offset 0, and files over 50 MiB. Verified against seven cases including a disc image renamed to look like source. Now that this pushes to a remote, this matters more than it would have locally. - AGENTS.md, the operating agreements: no game data ever, reproduce the PS2 float model rather than approximating it, bound every read, verify against the real disc. - PROVENANCE.md, recording that this follows ReRAC (ISC) and learns from rac2-gc-decomp (MIT). Wrench is used as a written specification only and no GPLv3 code is copied, since that would relicense everything derived from it. RAC2Decomp is explicitly not used: its provenance is disputed in the upstream community reference, and it targets the wrong region. - docs/roadmap.md, phased so the riskiest unknowns are retired early. The two that matter: overlay relocation transfers from ReRAC and makes 27 level overlays tractable, while VU1 microcode is binary and is the hardest single item. Phase 5 is a deliberately scoped Veldin vertical slice as the go/no-go.
35 lines
1.8 KiB
Rust
35 lines
1.8 KiB
Rust
//! The application: renderer, hardware models, and the frame loop.
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//!
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//! Reimplements the pieces of the PlayStation 2 that the game talks to, so the
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//! game logic in `gc-game` can be written as ordinary Rust that draws and
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//! sounds like the original.
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//!
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//! # Hardware being modelled
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//!
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//! * **Graphics Synthesizer (GS)** - fixed-function rasteriser. No shaders on
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//! the real hardware: the GS does texture mapping, alpha and blend rules,
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//! and z/stencil. Here that becomes wgpu plus explicit handling of the GS's
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//! own rules (its `round(log2(z/n) + K)` mip selection, its blend and alpha
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//! test behaviour, its alpha-0x80-is-1.0 convention).
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//! * **VU0 / VU1** - vector units running microcode uploaded from the disc.
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//! Skinning, lighting and transform setup live here. The microcode is
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//! **binary** in the game's `.vutext` section, so it is reverse engineered
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//! rather than parsed: this is the single hardest item in the project.
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//! * **DMA and GIF/VIF packets** - the game streams geometry to the GS through
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//! tag-split packet lists. Those packet formats are the input to rendering.
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//! * **SPU2 / IOP** - audio and the disc interface, in `gc-video` and
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//! `gc-extract` respectively.
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//!
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//! # Divergence from the first game
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//!
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//! R&C2's levels are spherical worlds, so camera, culling, fog and the sky are
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//! all effectively rewritten compared with Ratchet & Clank (2002). Geometry
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//! subsystems carry over in shape - `tfrag`, `tie`, `shrub`, `moby` are the
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//! same four - but their behaviour on a sphere is new work.
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//!
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//! # Reference frame
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//!
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//! The port is validated against PCSX2 by replaying recorded input and
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//! comparing frames. Without that loop, "looks close" and "is correct" drift
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//! apart, and this game's difficulty and movement make that drift very
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//! noticeable.
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