Reverse-engineer the single-stream XBG7 geometry layout (clean-room: hex
inspection + geometric validation of the retail disc's
hidden/resource3d/*.xpr, no game code copied) and present models as
textured 3D meshes in the explorer.
Format (docs/re/structures/xbg7-mesh.md): XBG7 geometry resources sit
inside XPR2 containers alongside TX2D textures. For ~25 single-stream
models (weapons, simple props) the data section is a sequence of
sub-meshes, each an u16-BE triangle-list index buffer followed (after a
fixed 12-byte header) by a stride-24 vertex buffer whose declaration is
in the descriptor: POSITION f32x3 @0x00, NORMAL f16x4 @0x0C, TEXCOORD
f16x2 @0x14. Sub-mesh (vtx,idx) counts come from descriptor tuples.
The +12 vertex offset is pinned by the recovered normals being exactly
unit-length (align16 lands 4 bytes early and silently corrupts every
field). A safety gate rejects any model whose indices are out of range
or whose mean |normal| is not ~1, declining garbage (Stage_S*
placeholders, the complex multi-stream hero-ship body) rather than
mis-decoding it.
- mesh.rs: Xbg7Model::from_xpr2 -> GameMesh { positions, normals, uvs,
indices }; standalone f16->f32; unit + real-disc tests (weapon decodes
to 215v/364t with unit normals + in-range UVs; DeltaSaber body
declined).
- texture.rs: from_xpr2_index / texture_names so the viewer can pick a
model's _col albedo map.
- viewer: loose .xpr with decodable XBG7 spawns Bevy meshes (real normals,
double-sided) textured with the albedo, framed by the orbit camera; the
central egui panel goes transparent so the 3D scene shows through.
Complex multi-stream body meshes (DeltaSaber f004, other vertex layouts)
remain undecoded and are cleanly declined — next target is dynamic RE.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
TXCM XPR2 resources are the game's world skyboxes (BG_Acheron, BG_Hargenteen,
…). The viewer showed only face 0 as a flat 2D image; now it decodes all 6 faces
and shows a labelled grid.
Formats (Bevy-free): X360Texture::cube_faces_from_xpr2() returns a Cubemap with 6
faces in D3D9 order (+X −X +Y −Y +Z −Z), or None for ordinary 2D textures. Face
layout derived from xenia's GetGuestTextureLayout — 6 back-to-back independently-
tiled surfaces, per-face stride = tiled-surface-size aligned to the 4 KiB
subresource boundary (kTextureSubresourceAlignmentBytes). Verified against real
BG_Acheron: data_size == 6 × 0x400000, and all 6 faces decode cleanly (own
Python decode + a disc test asserting 6×4 MiB faces and face 0 == the validated
from_xpr2 green-planet decode). Extracted a shared decode_surface() helper so the
2D and cube paths are byte-identical; from_xpr2 output unchanged (re-verified).
Viewer: new SkyboxPreview resource (6 egui face textures, reusing the existing
per-format x360_texture_to_bevy_image); populated in apply_loaded_texture's TXCM
branch; freed/reset alongside the other previews (factored free_texture/
free_skybox helpers). Central panel gains a skybox branch rendering a 3-column
labelled face grid.
DEFERRED (per "do not guess, else defer"): the interactive 3D skybox. Face data +
D3D9 order are validated, but wgpu cube-sampling handedness can't be confirmed
without eyeballing the GUI — a wrong-oriented skybox is worse than the correct
labelled grid. The grid is the reliable deliverable; the 3D look-around is a
follow-up once orientation is visually confirmed.
(Background agent did the investigation/validation but was blocked from writing
files; implemented here in the main tree from its findings, independently
re-verified.)
23 formats tests + disc cubemap test pass; viewer/CLI build; face-0 export
re-verified as the green planet.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The dword-swap that fixes DXT1 is a property of the BC1 COLOUR block, not of
BCn in general. RE on a DXT5A (BC4) mask showed the alpha block is byte-indexed
and wants the endian swap ALONE — dword-swapping it makes it worse. The blanket
swap from the previous commit was therefore breaking the (common) DXT5A/DXN
alpha & normal masks.
Now targeted by format:
- DXT1 : swap dwords of each 8-byte colour block (verified).
- DXT2_3 / DXT4_5 : swap only the colour half (bytes 8..16) of each 16-byte
block; alpha half endian-only. TENTATIVE — these formats
are near-absent in the game assets, so unvalidated against
a clear image.
- DXT5A / DXN : no dword swap (endian only).
DXT1 export re-verified clean (weapon skins); 16 formats tests pass.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
DXT1 (108/137 textures in Base.xpr — the bulk of picture assets) decoded to
noise. Root cause found by RE: Xbox 360 BCn blocks store the two 32-bit words
of each 64-bit sub-block in the opposite order to the PC/DDS layout — colour
endpoints live in the HIGH dword, indices in the low one. The endian field
(k8in16) only fixes byte order within the 16-bit words; it does not reorder the
dwords, so without this every DXT texture transposed endpoints/indices → noise.
Isolation that led here:
- de-tile proven correct for bpb=8 (coherent per-block signature map; the
linear read is scrambled) — same faithful Xenos Tiled2D as the verified
bpb=4 ARGB path (green Acheron backdrop).
- inspecting a smooth region, coherent colour endpoints appeared only in
bytes[4..8], with the high-entropy indices in bytes[0..4].
Fix: swap_bc_block_dwords() swaps the two dwords within each 64-bit unit after
the byte-level endian swap, for every BCn format. Verified in the real Rust CLI:
weapon skins (rou_f001_wep_*) now decode to clean, recognisable images.
Viewer: DXT1 is fixed transparently (from_xpr2 feeds tex.data straight to the
GPU as Bc1). Also corrected the uncompressed path — post-swap k_8_8_8_8 is
[A,R,G,B]; reorder to [R,G,B,A] and upload as Rgba8UnormSrgb (was Bgra8, wrong).
Knob: XPR_NO_BC_DWORD_SWAP disables the swap for A/B validation.
KNOWN REMAINING: 16-byte blocks (BC2/DXT3, BC3/DXT5) and BC4/BC5 (DXT5A/DXN)
still need their alpha+colour half layout worked out — they decode to noise for
now. DXT1 + uncompressed + cubemaps are correct.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Reworks the XPR2 texture path after RE against the retail disc (viewer
previews were scrambled/failed).
- de-tile: replace the naive Morton-over-32×32 approximation with the
faithful Xenos Tiled2D bank/pipe/macro-tile address formula (ported
from xenia texture_address.h). Verified correct: the Acheron backdrop
decodes to a sharp planet with its spiral storm.
- endian: undo the X360 word byte-swap per the fetch-constant endianness
field (k8in16/k8in32/k16in32) — without it BCn/ARGB data is noise.
- cubemaps: parse TXCM resources (skybox/backdrops), decoding face 0,
instead of erroring "No TX2D found".
- A8R8G8B8: correct channel order after the k8in32 swap ([A,R,G,B]→RGBA)
— the Acheron backdrop is now correctly green, not red.
- XPR files are texture PACKS; add XPR_RES_INDEX to select a resource.
- CLI `texture export` now writes real PNGs (texpresso BCn decode +
image), replacing the stub. Adds texpresso + image deps.
- tests/texture_disc.rs: integration test running the pipeline over real
disc .xpr files (28/28 parse). RE debug knobs: XPR_NO_DETILE /
XPR_NO_ENDIAN / XPR_FORCE_ENDIAN.
KNOWN ISSUE: mipmapped DXT1 textures still decode to noise — mip 0 is
not at base_address in the multi-resource packs (localized to a mip
storage-offset quirk; uncompressed + de-tile + endian are all verified).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
