Eyebrows

Maturity: Draft. Consolidated from the vanilla 2.31 resources (female and male), ArchiveXL 1.27.3's bundled brow files, three installed brow mods, the Modding Docs and a read-only audit of the Studio preview (26 September 2026), and the brow editor's phase 0 measurements (27 September). Nothing here has runtime evidence of its own. Evidence grades follow the knowledge rules: source engine, framework or tool source or compiled programs, resource extracted game or mod resources, [offline] measured from them, wiki Modding Docs text or image, runtime running game, hypothesis not yet established. Provenance, hashes and measurements are in the brows and cheeks evidence and experiment 025, which also lists every texture's path hash and data hash.

This page answers how a brow gets from the character creator onto V's face, how mods add brows, and what that means for a Studio brow designer. The option catalogue is in the CC file chain; the double-diffuse shader is in materials and shaders §4.5 and hair shading §6. The design options built on these facts are in the brows and cheeks brief, and the proposed editor in the brow editor design.

1. The chain at a glance

Style is a texture set, not geometry resource. Every style draws the same 390 vertices; the style's material swaps three textures on the brow's own UV layout. The texture numbering is offset: styles 01–08 use sets 01–08, styles 09–16 use sets 12–19. Sets 09–11 and all heb_ma__* textures are unused by the player; the male mesh uses the same heb__base_* textures.

All vanilla brow textures allow texture downgrade and have mip bias 0; their alpha mips are plain 2 × 2 box reductions resource [offline]. In glTF UV (below) the 13 creator styles' content spans u 0.03–0.97, v 0.16–0.71 of the brow UV area, entirely inside both body types' footprints [offline]. Sets 17–19 (styles 14–16, no creator option) are placeholders: alpha 255 everywhere with near-black RGB, so they would paint the whole strip dark if a mod offered them; sets 09–11 are ordinary painted brows without a _ds resource.

2. Geometry, deformation and placement

• A lifted strip of the head resource. Every brow vertex is a distinct head vertex pushed out along the head's normal by 0.35 mm (0.344–0.354; male 0.338–0.356), not the 0.40 mm of the makeup, lip, freckle and pimple decals (face makeup §2). 654 of the 664 triangles are head triangles; the rest are re-triangulated. The gap holds under the morph targets (median 0.35 mm, range 0.26–0.52). Why brows sit lower than the makeup is unknown [hypothesis: an authoring choice; both lifts clear the skin].
• Footprint and density resource. About 2,508 mm² (1,250 per brow; male 2,752), extent 119 × 25 × 45 mm. The 512 × 256 vanilla textures give about 0.14 mm per texel, coarser than a single brow hair; vanilla brows are painted, not hair-by-hair. The same triangles in head UV0 run at 418 mm per UV unit.
• Orientation resource. WolvenKit's glTF export writes v = 1 − the stored v, and XBMs store their rows bottom first, so in glTF UV with image rows top-down the brow is upright (the same pair of flips as the eye plate, experiment 019). u runs medial to lateral on both brows (about 0.02 at the nose end, 0.98 at the tail).
• The UV is not isometric [offline]. Per triangle, the female strip runs 53–93 mm per unit u and 28–44 per unit v (5–95 %, area-weighted), the u and v directions are up to 26° from perpendicular, and the upper edge is stretched (88 mm per u near the top, 55 near the bottom). Against one constant scale the median triangle's worst length error is 22 %; male 28 %. At 2048 × 1024 a texel is 0.026–0.045 × 0.027–0.043 mm (female). Anything drawn in millimetres must use the per-triangle metric.
• Both brows share one UV area resource. 96 % of the UVs are shared (male: all within 4 texels at 2048) and u is not flipped, so one texture draws both brows identically and the two brows' footprints are the same texels. A per-side asymmetric brow is impossible on this mesh without new UVs.
• Male and female footprints [offline]. At 2048 × 1024 the female strip covers 53 % of the texture (u 0.022–0.985, v 0.162–0.979), the male 44 % (u 0.029–0.924, v 0.111–0.955), and their intersection 42 %: 80 % of the female footprint and 96 % of the male, bbox u 0.029–0.924, v 0.162–0.955. At the same texel the male strip is 0.65–1.41 × the female's length along the brow and 0.99–1.59 × across (medians 0.96 and 1.21), so a shared texture looks about 20 % taller on a masculine V.
• Tangent frame source resource. The double-diffuse vertex program (17205971338381575357) passes the mesh tangent T and B = cross(N, T) · w; the pixel program places the map's x along T and y along B. Stored tangents follow +u, and the stored sign w is +1 on V's right brow and −1 on the left, matching the mirrored UV, so B points down the face on both brows: red tilts toward the tail, green toward the bottom of the upright image. Every painted vanilla set and the three mods inspected follow that convention [offline, inferred from alpha as a height proxy]. WolvenKit's GLB export negates w together with v, so a renderer using the exported tangents must negate green to match the game.
• Skinning follows the face rig resource. 74 joints are declared and 70 weighted (brow rows A/B/C, lids, cheeks, nose), up to eight influences per vertex, and 97.7 % of vertices carry exactly the head vertex's weights. Brows move with facial animation because they are skinned to the same face-rig bones as the head, driven through the face_rig component; the Studio's idle confirms nonzero brow-card motion (brow idle gap). In the creator, opening the eyes section plays ui_closeup_shot_eyes once, which carries strong bilateral brow motion; the loop is ui_closeup_shot (facial expressions §5).
• Morphs resource. The female brow morph carries all 105 face targets (male 100), but only the eyes, nose and jaw targets move it; the mouth and ear targets are zero. There is no vanilla brow-shape slider; brow height follows the eye shape.

3. Material and colour

Parameters set by eyebrows_grad__default.mi resource; the arithmetic is source (pixel program 7624081209775720613 and its Discarded twin 8834363738920290566, which differ only by the engine's dissolve; decal reference §5.1, brow material study):

The brow is a post_gbuffer decal: it blends colour in square-root space into the skin's G-buffer and is lit as Subsurface skin, once (materials §2.4).

Brow colour and hair colour resource:

• The 35 brow colours are the 35 hair colours, with the same names, localisation keys (UI-CharacterCreation-NN_<colour>) and icons.
• Each per-colour .mi sets only GradientMap = …\cap_gradiants\hh_cap_grad__<colour>.xbm, the same file the hair cap materials use for that colour (for example hair_profiles\brown_liquorice__cap.mi on mesh_decal_gradientmap_recolor.mt). black_carbon inherits the template default; phoenix_fire also sets GradientMapUV 0.75.
• The choices are independent: brows link on eyebrows color, hair on hairstyle color, and no .hp hair profile is involved in brows. Picking a hair colour never changes the brow colour, and a hair-profile replacer (.hp) does not recolour brows; a gradient replacer (hh_cap_grad__*.xbm) recolours both brows and hair caps.
• Vanilla data slips: female blonde_golden__11 uses the blonde-platinum gradient, female purple_blonde__14/15/16 use purple ombre, male liliac_ombre__14/15/16 use purple blonde, and app 15's female__24_purple_ombre points at purple_ombre__16. A renderer must follow the data, not the colour name.

4. How mods add brows

Three installed routes, and ArchiveXL's own brow framework underneath them (evidence):

ArchiveXL's brow framework resource source. The bundled PlayerCustomizationBrows{Fix,Scope,Patch}.xl remaps the vanilla brow apps per gender, defines the scopes player_{wa,ma}_brows.{app,mesh,morphtarget}, and patches archive_xl\characters\common\hair\h1_base_color_patch.mesh (35 name-only appearances) into every mesh in the brow scope. A CCXL brow mesh therefore defines only black_carbon, with the dynamic material pair @context BrowsBaseMaterial (the style .mi) and @brows (baseMaterial = the style .mi, GradientMap = *base\…\cap_gradiants\hh_cap_grad__{material}.xbm); ArchiveXL expands every other colour name, and hair-colour packs that patch the brow scope (for example Ratstick's Washed Out) add their colours to every scoped brow at once. The wiki's CCXL eyebrows guide (lumad11, 2025; later edits by manavortex) documents the same recipe: per-gender app, morph and mesh with a shared .mi holding only _d, _ds and _n, a Soft resource flag, and the options added to the TPP, character_customization and TPP_photomode head groups; its screenshot billede.png shows those three groups, and 2025-09-16 13 43 56.png an app with meshAppearance black_carbon and a full chunk mask wiki. The scopes and extensions guide (manavortex) warns that several styles in one mesh block later colour extension, so ship one mesh per style wiki.

How the mods ship their textures resource. Arkhe's Beautiful EYEBROWS II: _d and _ds 2048 × 1024 uncompressed RGBA8 (10.67 MiB each, 12 mips; its _ds is isGamma 0 with black RGB), _n 2048 × 1024 BC5; its material raises NormalAlpha to 0.8 and lowers GradientMapIntensity to 0.5. Arkhe's SET 01 replacer: 2048 × 1024 BC7, BC7 and BC5. Even More Brows: vanilla sizes and formats with vanilla material values. All three set allowTextureDowngrade 0. Their _d tone differs widely: Even More Brows is near white (linear ≈ 1.0, so about 2 × the gradient colour at intensity 2), Arkhe II linear 0.55 at intensity 0.5 (0.28 ×), vanilla 0.30 at intensity 2 (0.6 ×) [offline].

Creator entries resource. The row label is the switcher choice's localizedName, plain text in every inspected resource: vanilla 01…13 and Common-Off, Arkhe Beautiful Eyebrows II 01…, Even More Brows EMB 01…. ArchiveXL merges switcher choices by that text, and a later duplicate replaces the earlier choice (CC file chain §5), so a label is an identity, not just a caption. Each mod style is a gameuiAppearanceInfo copying the vanilla fields: uiSlot eyebrows_color, link eyebrows color, linkController 1, index 191, randomizeCategory Eyebrows, localizedName LocKey#43266, useThumbnails 1, a Soft app, and 35 definitions that reuse the vanilla colour keys and icons (UI-CharacterCreation-05_brown_liquorice, OptionsIcons.BrownLiquorice) under names matching the app's appearances (05_brown_liquorice; vanilla uses female__05_brown_liquorice). The mods list their appearance options in the TPP, character_customization and TPP_photomode head groups; only vanilla also lists the switcher, in character_customization.

The route an XF-built brow would use [source + resource; runtime untested for XF output]: the CCXL named merge into eyebrows, a per-style brow mesh in ArchiveXL's player_*_brows scope with the black_carbon / @brows dynamic material, and options in the three head groups. That gives every installed hair-colour pack's colours for free and keeps the vanilla colour row; it needs no new selector and no per-mod code.

5. What the Studio draws today

Brows render from the resolver's output for any vanilla or CCXL choice (P0 of the head CC render plan): the planner picks the chunk by the eyebrows_color slot and the TPP group, and the doubleDiffuseDecal adapter (src/brow-material.ts) reproduces the squared two-alpha coverage, the gradient colour and the square-root blend over the resolved skin through a per-vertex underlay source. Brows follow the facial morphs by (target, region) and join the idle rig. Not reproduced source:

• the brow's normal write (0.4, mode 1) and roughness write (≈ 0.50): the adapter draws a fixed roughness 0.8, although the newer face-decal family (src/face-decal-material.ts) already implements both for the same template;
• the game's authored mips (the browser builds its own; mip gate);
• brow wrinkle shading from the idle solver (brow idle gap); the skin program's wrinkle driver (UV-rectangle regions × animation float tracks) is decoded in the skin reference §5.6, while which solver outputs feed its tracks is hypothesis.

The Character panel's brow colour swatches are derived from the same chain: the strand colour (gradient × intensity × the diffuse tone, read at a 512-px mip and weighted by coverage squared). A gradient or material replacer changes them, and a set that derives dark and clustered is shown spread apart, with the true colour kept (hair shading §6.1).

There is no brow authoring of any kind: no part, painter, texture injection or exporter.

6. What this means for a brow designer

Open questions

1. Why are brows lifted 0.35 mm while every other face decal is 0.40 mm, and does the difference matter for draw order against eye makeup (both are EMP_Normal)?
2. What does GradientMapUV mean exactly? Answered resource: the u coordinate along the 32-texel ramp, read through a clamping linear sampler, so 1 is exactly the last texel and 0.75 blends texels 23 and 24 (§3).
3. Does the double-diffuse program apply UVScale/UVOffset to all three textures? Answered source: yes, like mesh_decal (decal reference §5.1).
4. What is the template default for the brow's metalness and NormalAlphaTex? Answered resource: black.xbm (metalness 0) and white.xbm.
5. Do the unused brow apps 14–16 and texture sets 09–11 draw anything if selected through a mod? Partly answered resource: styles 14–16 (apps 14–16) use texture sets 17–19, which are full-coverage near-black placeholders and would darken the whole strip; sets 09–11 are ordinary painted brows. Rendering is untested.
6. Does a brow mesh with separate per-side UVs (positions and skin bytes unchanged) render and deform identically in game?

In-game test asks

Batch into one prepared session; record game, ArchiveXL and whether Phantom Liberty is installed.

1. Brow colour is not hair colour. In the creator, choose hair brown_liquorice and brows blonde_platinum, then switch hair to black_carbon: the brows must not change.
2. Brow gloss. Photo mode, frontal close-up of brow style 3 under one light moved from above to the side: a brow writing roughness 0.5 over skin at about 0.6 should show a faint sheen on the hairs; compare with the preview.
3. Brow and eye makeup overlap. Eye makeup style 05 black with brow style 1: capture whether the makeup draws over the brow hairs where they overlap near the tail (both decals, 0.40 against 0.35 mm).

Related pages

Face makeup · CC file chain · Head CC rendering · Hair shading · Materials and shaders · Mod loading · Evidence · Brows and cheeks brief