How Saints Row: The Third builds characters

1 The whole pipeline

2 Where the data lives

Everything is in packfiles/pc/cache/*.vpp_pc (version 6 packfiles, zlib-compressed). Tables are XML (.xtbl), and names are stored as a Volition CRC: the reflected CRC-32 table with init 0 and no final xor, over the lower-cased string.

3 Sliders, keys and morph weights

player_creation.xtbl holds 110 sliders in 12 sets. A slider doesn't map to one shape. It has keys, and each key names a morph target and three numbers. FUN_009f65c0 turns slider value s into a weight per key:

t  = clamp((s − Nill) / (Full − Nill), 0, 1)
t2 = clamp((s − Nill) / (Neg  − Nill), 0, 1)      // only if Neg_Value is present
if t2 > t:  t = −t2                               // the sign flip at 0x9f6758 (missing from Ghidra's decompile)
w  = Morph_Scalar · t

pos[v] = f32((double)q / 32767.0 · w · A + pos[v])   // SSE2, per axis
nrm[v] += ((byte/255)·2 − 1) · w · B

4 Presets, the body triangle and Randomise

The Gender, Race and Figure buttons call pcr_apply_preset, which resets every slider to its Initial_Value, applies the race grid (e.g. male_asian: asian = 1, body fat = 1) and the figure, then sets skin, hair and default layers. Race is just another morph target, set to 1.

Randomise

The creator's Randomise is plain Lua: for each face set it calls pcr_apply_morph_value(set, id, rand_float(0.5 − Rand_Range, 0.5 + Rand_Range)), then picks a random eye layer and some face features. Every random draw in the game reads from one engine-wide table of 8192 MT19937 outputs, refilled from a clock seed at start-up. So a session can't be replayed, but a given seed is fully deterministic. The demo uses a seed you type in.

5 Normal maps follow the body

Skin detail (muscle definition, fat folds, age) isn't geometry. player_creation_normal_maps.xtbl defines weights for Base, Skinny, Fat, Muscle and Age as products of piecewise curves over the body sliders. The blend pass then sets fat = fat^¼ and base = max(0, 1 − skinny − fat − muscle). It mixes five race- and gender-specific DXT5nm maps into one render target with the cust_normal_map_blend pixel shader:

n.xy = Σ −wᵢ · ((2a−1)(2r−1), 2g−1)ᵢ     // decode each DXT5nm map
if |n.xy| > 1: normalise;   n.z = √(1 − |n.xy|²);   out = (n + 1) / 2

For female_black + average: base 0.25, skinny 0.25, fat 0.5 (0.0625^¼), muscle 0.

6 Skin and the composite texture

The body's diffuse texture is rebuilt into a 2048×1024 render target whenever the look changes (FUN_009fa8e0), in two passes:

55 skin colours

Each entry is an HSB offset, not a colour. These swatches apply each offset to the median skin texel of the base diffuse, so they're approximate. Lighting and the shader ball change the final look a lot.

Layers

The skin shader

n      = tangent-space normal from the blended Normal_Map (2nd UV set)
uv_sb  = view-space n.xy · 0.5 + 0.5
matcap = mix(Sphere_Map_1(uv_sb), Sphere_Map_2(uv_sb), Blend_Map(uv0).r)
out    = L_diffuse · matcap · (composite · Diffuse_Color) · 2 + L_specular · Specular_Alpha · Specular_Color

7 Hair

Hair is an ordinary clothing item in the head hair slot (51 styles), with its own morph targets so it follows the head. Colour isn't a texture tint. ir_sr3pchair builds it per pixel from the Dob map (B = strand brightness b, G = opacity, R = specular) and four parameters:

sat = sat_dark + (sat_light − sat_dark) · b
val = b · Brightness + bias
rgb = HSV(Hue / 60, sat, val)  +  specular(bright ↔ dark by b)

35 hair colours. Each swatch is HSV(Hue, Saturation_light, Brightness), the colour of the brightest strand (b = 1) before lighting.

Most hair styles have a second wear option (cm_pulledintohat and similar) whose required flag is hat active. Put on a cap and the hair switches to a squashed mesh.

8 Clothing and accessories

Dyeing: three colours through a pattern mask

P      = Pattern_Map(uv1 · (TilingU, TilingV))                   // second UV set, often a tiny tiling mask
colour = lerp(lerp(lerp(1, primary, P.b), secondary, P.g), tertiary, P.r) · Diffuse_Map(uv0) · Diffuse_Color

9 NPCs: a different system

Ambient NPCs don't use sliders, presets or the composite. Each character_definitions.xtbl entry is a hand-made body mesh plus heads. A head is the shared npc_basehead (1426 vertices) plus one morph target, named after the head, at weight 1. Per spawn (FUN_00950660, in this RNG order):

1. Palette: rand_int a primary colour from the character's palette tree, then a secondary under it, then a tertiary.
2. Props: for each prop group, roll against its chance, then pick an item and a sub-item. A prop is usually a VID of the NPC's own mesh: hood up or down, hair, an iPod.
3. Head: rand_int over the definition's heads.
4. Hair tint: rand_int over the head's list of hair shader balls. Hair is painted into the head texture and coloured through the matcap.

10 How much variety

The top bar ignores the sliders (≈10²⁰⁸ discrete combinations, matching the demo's Variety tab). The bottom bar adds the sliders at their UI step size. Clothing dyes alone are 126³ ≈ 2 million colourings per item.

11 Known gaps in the re-implementation

• Lighting. The demo replaces the inferred-lighting buffer with a key light, a fill light and ambient. The material maths follows the shaders.
• Eyes, lashes, hair specular are approximated, not ported.
• Clothing normal maps, decals, cloth simulation and glow animations aren't done.
• Two hair textures are drawn opaque. "Off The Shoulder" and M_PlayerMedium have a copy of the brightness in the opacity channel. Read literally, they'd be see-through.
• Wear-option resolution is my reading of the flags. The game function isn't decompiled yet.
• Handedness. The game is left-handed (Direct3D), so the demo mirrors X so that text on clothing reads correctly.
• Not yet compared side by side with the running game.