Attire estimates

Attire estimates

These functions estimate what an outfit weighs, where it weighs, what it costs to walk in, what it covers and what it stops. They are template estimates for a game. Each constant has an Evidence grade and a source. The humanoid's engineering use stays refused. See Humanoid fidelity.

.venv/bin/mojo run -I . tools/attire_report.mojo --outfit knight

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

Mass

garment_mass(piece, fabric) is a garment's area times its fabric's areal density. A garment weighs its whole shell, the parts that the garments over it hide too. dress keeps each whole shell in Dressed.shells.

Mail's areal density is set so a hauberk on the six-foot template weighs 9.3 kg. That is the weight of a 15th-century hauberk at the Cleveland Museum of Art. Plate is 2 mm of steel at 7,850 kg/m³.

worn_tallies(outfit, dressed) splits each triangle's mass among the joints by its skin weights. It gives one InertiaTally per joint, at rest, in the pelvis frame. Add them to the body's own segments with InertiaTally.add. outfit_mass(tallies) gives the total.

On the template, the knight outfit weighs about 40 kg. Askew, Formenti and Minetti give 30 to 50 kg for a field harness.

Locomotion cost

locomotion_cost(tallies, body) estimates the metabolic cost of walking in an outfit, as a multiple of walking unloaded.

Where the load is	Cost per unit of its share of body mass
trunk and head	1.0
arms	1.0
legs	4.5

A load on the legs costs more than one on the trunk, as Askew, Formenti and Minetti found. The coefficients are a design choice. They are set for a 40 kg harness on a 75 kg man, 30 percent of it on the legs. Walking in it costs about 2.1 times as much. That is the low end of the study's 2.1 to 2.3 for walking.

Coverage

coverage(skin, rig, outfit) gives the share of each body region's skin that an outfit covers, by area. Pass the skin before dress changes it. A region with no skin on that mesh has zero; the body mesh has no hands, which are meshes of their own.

Protection

protection(outfit, rig, joint, along, blow) passes a blow's energy through the layers over one point, from the outside in. The blow lands on a joint's bone, a fraction along of the way down it. A garment is a layer there when it covers that point at least by half. Each layer takes the energy it needs to be pierced. The blow stops in the first layer that takes all it has left.

Fabric	Energy to pierce	Grade	Source
LINEN	5 J	design	textile practice
WOOL, SILK	6 J	design	textile practice
VELVET	8 J	design	textile practice
LEATHER	20 J	design	textile practice
PADDING	40 J	from text	Williams
MAIL	80 J	from text	Williams
PLATE	175 J at 2 mm, with the square of the thickness	from text	Williams

Alan Williams's tests give 60 to 130 J for a hand blow and about 120 J for an arrow through mail over a padded jack. They give about 55 J at 1 mm and 175 J at 2 mm for mild steel plate. The square law is fitted to 2 mm, so it gives about 44 J at 1 mm. Secondary sources disagree on some of these figures. Check them against the original before you rely on them.

Protection holds the BlowOutcome, STOPPED or PIERCED, the garment that stopped the blow, and the energy left.

Noise and visibility

noise(outfit) and visibility(outfit) are zero-through-one hooks for a game's stealth, as Kingdom Come: Deliverance has them.

• Noise: plate rings at 0.5, mail rattles at 0.3, leather creaks at 0.06, padding at 0.03, and cloth at 0.01. The sum is held to one.
• Visibility: the outermost garment of each slot shows. Its primary dye's brightness counts, and polished plate adds 0.3.

The report

attire_report gathers every estimate for one dressed outfit into one record. tools/attire_report.mojo builds the six-foot template, dresses it, and prints the record as JSON. The options are --outfit, --file, --triangles and --body-kg. The record says "template_estimate": true and gives each garment's grade and source.

Sources

• Askew, Formenti and Minetti, "Limitations imposed by wearing armour on Medieval soldiers' locomotor performance", Proc. R. Soc. B, 2012.
• Alan Williams, "The Knight and the Blast Furnace", 2003, and his tests as quoted by later writers.
• Lazar and Kraner, a study of the thickness of eight breastplates, 2019.
• The Cleveland Museum of Art, hauberks of the 15th century.

Tests

tests/test_attire_estimate.mojo covers this page.