arcattackandClaude Opus 4.8
7b7d465e5e
Clean, self-contained extraction of the BattleTech-specific work from the
reverse-engineering workspace -- engine + game + content + build, with nothing
from Red Planet or the raw archive dumps. Builds green (Win32) and runs the
single-player drive->animate->target->fire->damage->destroy loop out of the box.
Layout:
engine/ MUNGA + MUNGA_L4 shared 2007 engine, carrying our BT render/loader
work (bgfload/L4D3D/L4VIDEO: BSL bit-slice decode, LOD/ground/shadow
models) + image codec; the minimal rp/ headers the audio HAL needs
game/ reconstructed BT logic + surviving-original BT source + fwd shims
+ WinMain launcher
content/ full runtime tree (BTL4.RES, VIDEO/, GAUGE/, AUDIO/, eggs, BTDPL.INI)
docs/ format specs + reconstruction ledgers
reference/ raw Ghidra pseudocode (recon source-of-truth) + decomp exporter
tools/ MP console emulator + map/resource scanners
One top-level CMake builds munga_engine lib + bt410_l4 game lib + btl4.exe.
All paths relativized (186 fwd shims + ~437 CMake abs paths -> repo-relative);
DXSDK is the one external, overridable via -DDXSDK. Verified: builds to a
byte-identical 2.27MB exe and runs combat (TARGET DESTROYED, 0 crashes) against
the bundled content.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
84 lines
5.8 KiB
Markdown
84 lines
5.8 KiB
Markdown
# Asset Pipeline — Textures, Materials & Gauges
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Companion to `BGF_FORMAT.md`. Covers how a model's surface resolves to pixels, and the cockpit
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gauge/HUD formats. Verified by hexdump against real content; header cites are `file:line` under
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`…/CODE/RP/MUNGA_L4/libDPL/`.
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## Format inventory (CONTENT/BT)
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| Ext | Count | Kind | Role |
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|---|---|---|---|
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| `.bgf` | 1275 | `DIV-BIZ2` FILETYPE=0 | 3D geometry (see BGF_FORMAT.md) |
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| `.bmf` | 2222 | `DIV-BIZ2` FILETYPE=1 | material + texture **libraries** (no pixels) |
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| `.vtx` | 5 | `DIV-VTX2` | raw RGB texel image |
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| `.tga` | 8 | Truevision TGA2 type-2 | 24-bit truecolor texel image |
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| `.sgi` | 0 | (loader exists) | RGBA texel image (none shipped) |
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| `.bsl` | 3 | `DIV-BSL2` | bit-slice / multi-image + mip container |
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| `.pcc` | 434 | ZSoft PCX, 8-bit RLE | cockpit HUD/gauge **raster** bitmaps |
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| `.gim` | 311 | ASCII INI | MFD/radar **vector** line-gauges (NOT raster) |
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| `.gat` | 3 | ASCII INI | gauge color/attribute table |
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Layout: `VIDEO/GEO/*.bgf`, `VIDEO/MAT/*.bmf`, `VIDEO/TEX/*.vtx,*.bsl` (+ `TEX/BUILD/*.tga`),
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`VIDEO/BUILD/*` staging, `GAUGE/*.gim,*.gat,*.pcc`, `MODELS/*.mod` (INI tying bgf+gim+sld).
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## Name-resolution chain (verified)
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```
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BGF geogroup SV_F_MATERIAL "library:material"
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→ open library.bmf
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→ MATERIAL chunk whose NAME == "material"
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→ its MATERIAL_TEXTURE (0x0021): [u8 type=2 NAMED][texture-name string]
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→ TEXTURE chunk whose NAME == that texture-name
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→ its TEXTURE_MAP (0x0011): image basename (no ext)
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→ loader appends ext, searches texmap path → .vtx/.tga/.sgi/.bsl
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```
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`dpfCreateMaterialName(extPath,library,mname)` `PFILE.H:821`.
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## .BMF chunk layout (same TLV grammar as BGF; tags in `PFBIZTAG.H:43-62`)
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**TEXTURE `0x0010`** (`dpfTEXTURE`, `__PFILE.H:120-137`): NAME `0x2008` (string); TEXTURE_MAP `0x0011`
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(basename string); MINIFY `0x0012`/MAGNIFY `0x0013` (mip/filter enums, `PFILE.H:155-162`); ALPHA `0x0014`
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{blend/cut/blendcut}; WRAP_U/V `0x0015/16` {repeat/clamp/select}; DETAIL `0x0017`; BITSLICE `0x0018` (u8 → .bsl slice).
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**MATERIAL `0x0020`** (`dpfMATERIAL`, `__PFILE.H:152-169`): NAME `0x2008`; MATERIAL_TEXTURE `0x0021`
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[`u8 type`(2=named)+name]; AMBIENT `0x0023`/DIFFUSE `0x0024` = 3×f32 RGB (verified); SPECULAR `0x0025`/
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EMISSIVE `0x0026`/OPACITY `0x0027` (optional, inferred 3-4 f32); RAMP `0x0028` (ramp-name string).
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**RAMP `0x0030`**: NAME + RAMP_DATA `0x0031` (float color data).
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## Pixel formats (normalize all to 32-bit RGBA at load)
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- **.VTX (`DIV-VTX2`):** TLV; size tag `0x2062` = two int32 (w,h, e.g. 128×128); body = **uncompressed RGB
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3 B/px**, top-to-bottom. Type enum `dpiBSLTYPE` (`PIMAGE.H:104-116`): MONO0-5/BILINEAR/RGB/RGBA.
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- **.TGA:** standard type-2, 24-bit BGR, TGA2 footer. `dpl_tgaRead`.
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- **.SGI:** RGBA (`dpl_sgiRead`; none shipped).
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- **.BSL (`DIV-BSL2`): DECODED — a BIT-SLICED multi-image container** (corpus-verified on all 66 archive
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BSLs; reference = the shipping WinTesla loader `DivLoader/VGCDivLoader.cpp:323-410`
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`LoadBSLFile`/`getBSLData` + Division `dsys/PIMAGE.H` `dpiBSLTYPE` + the content build scripts
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`img2vtx.exe -b -mN <tga>`). Header (int32 LE): w `@0x08`, h `@0x0C`, depth `@0x10` (bits per slice,
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always 4), tableBytes `@0x14` (directory length counted from the nEntries field; imageDataOffset =
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`0x18 + tableBytes`), nEntries `@0x18`; directory entries `{int32 recLen; int32 sliceType; char
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name[recLen-4]}` — **entry names are authoring records only, read-and-discarded at runtime**; then
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`w*h` little-endian 32-bit texel WORDS. Byte 0 of each word = pad (structurally unused, 0 in all 66
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files); the other 3 bytes = SIX independent **4-bit GRAYSCALE slices**, nibble PAIR-SWAPPED (even slice
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= HIGH nibble): slice0=bits12-15, 1=8-11, 2=20-23, 3=16-19, 4=28-31, 5=24-27 (`shift=(c+((c+1)%2)*2)*4`,
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value returned `<<4` = 0x00..0xF0). sliceType 7 = **RGB444** (r=s5,g=s4,b=s3), 8 = **RGBA4444** (+a=s2);
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both coexist with mono slices in one file (BDAM/BEXP/BDET). Slice SELECTION = the BMF TEXTURE record's
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`BITSLICE` tag `0x18` (u8; **absent = slice 0**) — e.g. BLHSKIN.BMF blkhwk1_tex=absent(0),
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blkhwk2/3/4_tex=01/02/03, all mapping image basename `blkhwk` → BLKHWK.BSL. Mono slices are colorized
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downstream by material RAMP (+ diffuse tint on neutral ramps) — all mech skins, vehicle atlases
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(BASEV = 6 gray sheets, NOT truecolor), logos, effects grit. ⚠ The previous "base image = trailing
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w*h*bpp, pixel order [pad,R,G,B]" claim was WRONG — it overlaid 2-3 different gray slices as RGB
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channels (the rainbow "graffiti" mech-skin bug); it survives as the `BT_BSL=0` diagnostic fallback in
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`port/src/image.cpp decodeBSL`.
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## Cockpit gauges
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- **.GIM** = ASCII INI, **vector** top-down line drawing for MFD/radar: `[lods] level0=3000…`,
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`[vertices] v0=x,y,z`, `[level0] linelist=<group> v0 v1 v2…`. First token = color/attr group resolved
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via `.gat`. Feeds the `dpl2d_*` 2D line path. Verified `AB01_GA.GIM`.
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- **.GAT** = ASCII INI: `[colors]`,`[groups] a_bld=amber1…` → group→palette-index. Verified `GAUGE.GAT`.
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- **.PCC** = ZSoft **PCX**, 8-bit RLE, 256-color palette (palette after `0x0C` EOF marker); 640×480-class.
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The actual HUD raster bitmaps → need 8-bit-palette → RGBA expansion. Verified `ADPAL.PCC`.
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## ⚠ Dependencies / open items
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1. **The retail texel raster set is NOT in this archive** — only the BUILD/logo subset of `.vtx/.tga/.bsl`
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ships. The 2222 `.bmf` reference maps that aren't here. **Need the full texture content from Nick**, or
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the renderer must tolerate missing maps and fall back to material DIFFUSE color.
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2. **No source for the `.gim/.gat/.pcc` loaders** — inside the closed `LIBDPL.LIB`. `.pcc`(PCX) and
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`.gim/.gat`(INI) are standard/simple. `.bsl` and `.vtx` are now FULLY decoded (see Pixel formats above;
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the shipping `DivLoader/VGCDivLoader.cpp` turned out to carry the reference reader for both).
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