---
id: asset-formats
title: "Asset Formats — MOD/SKL/ANI/BMF/BSL/textures/gauges/collision"
status: established
source_sections: "PROGRESS_LOG.md §5; docs/ASSET_PIPELINE.md; docs/BGF_FORMAT.md"
related_topics: [bgf-format, rendering, locomotion, combat-damage, gauges-hud]
key_terms: [MOD, SKL, ANI, BMF, BSL, VTX, SLD, DZM, PCC, GIM, material-ramp]
---

# Asset Formats

All reverse-engineered. Geometry (BGF) has its own topic ([[bgf-format]]); the full pixel/material
spec is `docs/ASSET_PIPELINE.md`. Full list: `docs/PROGRESS_LOG.md §5`.

## Definition / skeleton / animation
- **`.MOD`** — INI mech/object definition: skeleton, skins, collision, gauges, physics, animations,
  class. The `.MOD` physics (MoverMass/drag/MaxAcceleration) governed thrust VEHICLES + collisions,
  NOT walk gait ([[locomotion]]). [T1]
- **`.SKL`** — INI joint skeleton. `[joint] parent=, Type=(hingex/y/z|ball|balltranslate),
  Object=part.bgf, dzone=, tranx/y/z, pitch/yaw/roll`. Build a **DCS tree**; neutral pose ≈
  translations (pyr≈0). [T1]
- **`.ANI`** — INI keyframe animation. `[HEADER] framecount/framerate(30)/skeletonfile`; `[frameN]`
  joint→**`pitch yaw roll` radians for EVERY joint type** (ANIMTOOL.cpp:140-142 parses the triple as
  EulerAngles unconditionally — the old "balltranslate→translate" note was wrong [T0]); a
  balltranslate joint ADDITIONALLY gets a per-frame translation from the separate **`[KeyJointPos]`**
  section (ANIMTOOL.cpp:478-483 packs EulerAngles+Vector3D; JMOVER/seqctl apply SetRotation +
  SetTranslation). For the root `jointlocal`, KeyJointPos.y = the gait vertical bob;
  `[RootTranslation]` per-keyframe `x y z` where **`.z` = forward root SPEED** (units/s). Walk anims
  have no baked root translation — forward motion is animation-driven from `.z` ([[locomotion]]).
  Walk/run CYCLE clips author NO body pitch — root keys are a ≤1.5° roll sway only; the authored
  LEAN lives in the transition (`rwl/rwr/wrl/wrr` jointhip ~7-12°) + `bmp` stagger (~25°) clips
  (2026-07-13 sweep of all 331 source ANIs). [T1]

## Materials / textures
- **`.BMF`** — `DIV-BIZ2` (FILETYPE=1) material+texture LIBRARY (no pixels). Material → DIFFUSE color
  + `MATERIAL_TEXTURE`→texture→`TEXTURE_MAP` image basename. Tags: `0x18 BITSLICE` (BSL slice select),
  `0x28` ramp ref, `0x26` emissive, `0x30/0x31` ramp def. [T1]
- **Texture pixels:** `.tga` (Truevision), `.vtx` (`DIV-VTX2`, trailing RGB), and **`.bsl`**
  (`DIV-BSL2` — a BIT-SLICED container: w*h 32-bit texel words holding SIX independent 4-bit
  GRAYSCALE sub-images (nibble pair-swapped, byte 0 pad) OR RGB444/RGBA4444 (sliceType 7/8). The BMF
  `0x18 BITSLICE` tag picks the slice, absent=0). Decoding BSL as RGB = the "rainbow/graffiti mech"
  bug. Reference reader: `DivLoader/VGCDivLoader.cpp:323-410`; archive-only — in-repo reimplementation: `engine/MUNGA_L4/image.cpp`. [T2]
- **`.VMF`** — `DIV-VIZ2` material SOURCE. Carries the `SCROLL` animation + `MAP{}` image binding for
  effects (beams/muzzle/smoke/sky). THE key effects asset ([[rendering]]). [T2]
- **[[material-ramp]]** — the IG board colours no-normal geometry by a 2-endpoint RAMP; details in
  [[bgf-format]] + [[rendering]]. [T2]

## Collision / damage / subsystems
- **`.SLD`** collision solids (Block/YCyl/Cone/Ramp/Wedge). Terrain is modeled AS collision volumes;
  see [[locomotion]] ground model + [[combat-damage]]. [T1]
- **`.DZM`** = INI damage-zone→material map (mech skin damage states). **`.DMG`/`.TBL`** damage
  zones/tables, **`.SUB`** subsystems (weapon params — DischargeTime/RechargeRate/WeaponRange),
  **`.CTL`** control maps. [T1]

## Cockpit HUD assets ([[gauges-hud]])
- **`.GIM`** vector MFD/radar line maps + **`.GAT`** color table; **`.PCC`** ZSoft PCX 8-bit gauge
  rasters (fonts helv15/helv42, label strips, dials). [T1]

## Key Relationships
- Geometry detail: [[bgf-format]]; pixel/material spec: `docs/ASSET_PIPELINE.md`.
- Consumed by: [[rendering]], [[locomotion]] (SKL/ANI), [[combat-damage]] (SLD/DZM/SUB), [[gauges-hud]] (GIM/PCC).