Garments

Garments

A garment is the covered part of a person's skin, moved out along the skin's normals and cut at clean hems. It follows any genome and stature, takes the skin's weights, and stands off every layer under it. See Outfits and armor to dress a person.

from extensions.attire.garment import gambeson, hauberk
from extensions.attire.outfit import Outfit, dress

var outfit = Outfit()
outfit.add(gambeson())
outfit.add(hauberk())
var dressed = dress(scene, assets, person, outfit)

This is not a three.js port. The code is in extensions/attire/.

What a garment holds

A Garment holds no mesh. dress makes its mesh from the skin of the person who wears it.

Field	Type	Meaning
slot	Slot	Where it goes: head, neck, shoulders, torso, arms, hands, waist, legs, feet or back.
layer	Layer	How far from the skin it sits: under, mid, outer, armor or over.
fabric	FabricKind	What it is made of.
cover	Cover	What it covers, joint by joint.
articulation	Articulation	How it follows the bones: flexible, rigid or lamed.
anchor, lames	Joint, Int	The bone a plate rides, and the number of lames.
pattern, dyes	DyePattern, four Color values	How it is dyed.
drape, ease	Int, Length	Smoothing passes of its shell, and how loose it is cut.

Every slot, layer, fabric, articulation, pattern, dye channel and wear channel is a type with is_valid. A bare integer does not compile.

Cover

A Cover gives each joint of the rig a span along its bone, from a start to an end. Each is a fraction of the bone's length from the joint.

Span	Meaning
reach_to(joint)	All of the joint's skin, past both ends of the bone.
reach_to(joint, 0.9)	From the joint to 0.9 of the bone. A long sleeve reaches 0.9 of the forearm.
reach_to(joint, 1, start=0.45)	From 0.45 of the bone to its end and past it. A boot covers the shin from 0.45 down.

The cover value of a skin vertex is the sum of its skin weights, each times its joint's coverage there. A span's end ramps linearly over 8 cm along the bone. The values are then smoothed over three passes. The garment is cut where the value is one half. So a hem runs as a clean curve round the limb, not along the edges of triangles.

face_open leaves an oval opening in front of the face in the head and the neck. A coif, a hood and a bascinet use it.

The shell

dress makes each garment in four steps.

1. It reads the skin once: positions, normals and the vertices that share one position.
2. It computes the standoff of each vertex: the garment's clearance and ease, past the outer face of each layer under it.
3. It moves each vertex out by its standoff and drapes the shell.
4. It drops what a layer over it hides, and cuts the shell at its hems.

A drape pass moves each covered vertex halfway to the mean of its neighbors. Then it pushes the vertex back out to its standoff. One pass keeps the skin's shape under a thin cloth. Twenty-four passes span the hollows, as a stiff plate does.

A layer under a garment lifts it in full inside and at that layer's hem. The lift fades out a quarter of a cover value past the hem. So a tunic rises smoothly over the top of a hose. No layer can pass through the layer under it at rest.

A triangle is hidden when every corner has a cover value of 0.75 or more from a layer over it. The skin and the inner layers drop these triangles. So skin cannot show through a garment when the body bends, and a dressed person costs about as many triangles as a bare one.

Fabrics

fabric(kind) gives the constants of a fabric. fabric_material(kind, tint) gives its physically based look, with vertex colors on and the scene's environment reflected.

Kind	Areal density	Thickness	Drape	Look
LINEN	200 g/m²	0.5 mm	1	sheen
WOOL	300 g/m²	1.2 mm	2	sheen
SILK	80 g/m²	0.2 mm	1	bright sheen
VELVET	350 g/m²	1.5 mm	2	colored sheen
LEATHER	1.7 kg/m²	2 mm	3	faint clear coat
PADDING	2.4 kg/m²	15 mm	6	sheen
MAIL	8.5 kg/m²	3 mm	3	rough metal
PLATE	15.7 kg/m²	2 mm	24	polished metal under a clear coat

ArealDensity is a Quantity[-2, 1, 0, 0], in extensions/attire/quantities.mojo. Its units are KILOGRAM_PER_SQUARE_METER, GRAM_PER_SQUARE_METER and OUNCE_PER_SQUARE_YARD. A metal shows what it reflects, so give the scene an environment.

Surface

dress gives each garment texture coordinates in meters, round its bones. Mail, padding and cloth then take a bump map that tiles at its true size.

Fabric	Bump map	Tile	Scale
MAIL	riveted rings, four in one	4 cm	0.6
PADDING	diamond quilting	6 cm	1.0
LINEN, WOOL, SILK, VELVET	two-over-two twill	4 mm	0.15
LEATHER, PLATE	none

garment_uvs(piece, rig) makes the coordinates in three steps.

1. It cuts the garment into one part for each chain of bones. A chain is a run of bones that bend less than about 45 degrees from each other, such as the upper arm and the forearm. A part is where its chain holds at least half of the skin's weight. The rest follows the chain that holds most of it.
2. It cuts each part along a seam down the back of its bones.
3. It sets u to the arc round the bone, at the chain's mean radius. It sets v to the distance down the chain.

So v runs on across the elbow and the knee, and no triangle mixes two chains. A pattern meets itself at the back seams and where a sleeve meets the body, as the panels of a sewn garment do.

SurfaceMaps makes each bump map once and gives it to every material that needs it. Each map is a 64-texel height image with a mip chain. In a full-body view a ring of mail is smaller than a pixel, and the mip chain turns the rings into a fine glint.

Dyes and wear

A garment has four dye channels: primary, secondary, trim and accent. A pattern says where each lies.

Pattern	Primary	Secondary
SOLID	everywhere	nowhere
PARTY	the wearer's right side	the left side
STRIPES	even bands round the body	odd bands
QUARTERLY	upper right and lower left	upper left and lower right

Every pattern puts the trim dye along each hem. dye_pattern cuts the garment along each boundary, so a boundary is a crisp line. Each vertex keeps its channel weights in a dye attribute.

Wear is four more channels in a wear attribute: dirt, blood, wet and damage. soil lays dirt from the lowest point up. stain lays any channel round a point. paint mixes the dyes, then the wear, into the color attribute.

stain(piece, BLOOD, Vector3(0.1, 1.2, 0.15), Length(0.08, METER), 0.9)
soil(piece, Length(0.3, METER), 0.6)
paint(piece, garment.dyes)

The wardrobe

wardrobe() gives sixteen medieval garments, from the skin out.

Garment	Slot	Layer	Fabric
shirt	torso	under	linen
hose	legs	under	wool
tunic	torso	mid	wool
gambeson	torso	mid	padding
hauberk	torso	outer	mail, brass at the hems
coif	head	outer	mail
hood	head	over	wool
boots	feet	outer	leather
gloves	hands	outer	leather
cuirass	torso	armor	plate
fauld	waist	armor	plate
pauldrons	shoulders	armor	plate
vambraces	arms	armor	plate
greaves	legs	armor	plate
bascinet	head	armor	plate
surcoat	torso	over	linen, per pale

Garments made elsewhere

An artist can model a garment on one body and export it to glTF. bind_garment reads where each vertex lies against that body's skin. It stores the joint that weighs most there and where the skin point stands from that joint, in statures. It also stores how far the vertex stands off the skin.

fit_garment puts the garment on another body. It goes to the same place from the same joint of the new rig, and finds the nearest point of the new skin. It stands the vertex off that point by the same distance. It never reads the old skin's topology. wear_fitted adds the result as a skinned mesh.

var binding = bind_garment(coat, maker_skin, maker.rig)
var fitted = fit_garment(binding, coat, wearer_skin, wearer.rig)
_ = wear_fitted(scene, assets, wearer, fitted^, look)

Why the shell comes from the skin

The plan first made each shell from the body's distance field. The skin is a better source, for three reasons. The garment shares the skin's vertices until it is cut, so it takes the skin's weights exactly. Hiding the skin under a garment is a test per vertex, with no search. And a shell costs one pass over the skin, so a test dresses a person in well under a second.

Roblox's cages and MakeHuman's mhclo files bind a garment to a body mesh from outside. Kingdom Come: Deliverance pushes each layer out of the one under it with ray casts. Here each layer stands off the layer under it vertex by vertex, because every layer has the same vertices.

Tests

tests/test_attire_kinds.mojo, test_attire_fabric.mojo, test_attire_mesh_ops.mojo, test_attire_cover.mojo, test_attire_shell.mojo, test_attire_surface.mojo, test_attire_dye.mojo, test_attire_garment.mojo and test_attire_binding.mojo cover this page. Each kind type has a file in tests/compile_fail/.