Magical gene / ground and strong white

Carapace Sheen

The coat gleams like a beetle's shell - glassy and deep where the body turns toward the light, paling underneath, with a bright ridge down the spine and a few pale blazes on each flank.

What it can come out as

Outcome	Carrying
Carapace Sheen	`Csh/Csh` · `Csh/n`
Wild type	`n/n`

How each one is actually drawn - region by region, and the layers it is built from - is on the coding tab.

Crossing two of them

Finding one

About 1 in 2,500 wild horses is born showing this. That is the whole of the supply: catch one, or make one with the carrot below. Breeds set their own pools and a breed built around this gene will carry it far more often than the wild population does.

Wild pair	Shows as	How often
`Csh/Csh`	Carapace Sheen	0.002% — 1 in 50,000
`Csh/n`	Carapace Sheen	0.038% — 1 in 2,632
`n/n`	Wild type	99.96%

Its gene carrot

The file

common/src/main/resources/horsegenetics/genes/carapace_sheen.json — a data-driven gene, not a Java class. It is listed in the index.json beside it and registered by Genes' class initialiser at startup.

Key	`horsegenetics.carapace_sheen`
Phase	magical — it adds signed colour in phase 3, after the pigment has resolved
Priority	226 — where it sits in the one `(priority, key)` paint order
Alleles	`Csh` · `n`
Varies per horse	2 values drawn once off the expressing allele copy, so a foal that inherits the copy inherits the look
Built from	CENTERLINE, NORMAL, PARTS, RAMP, SPOTS, TOWARD

Why it is built this way

This is the gene the NORMAL mask was added for, and it is worth being plain about what the mask does and does not deliver. True iridescence is a function of the angle between the surface and the VIEWER, and the coat here is a baked texture: nothing in this module ever learns where a camera is, so a colour that shifts as the horse turns is out of reach and will stay out of reach while the coat is a PNG. What NORMAL measures instead is which way the surface itself faces, which is the structural half of the effect - the sheen sits on the planes that turn up into the light and thins on the ones that turn away, and it stays there. The import shipped a vertical RAMP standing in for this; a ramp is a position band and gets it wrong the moment the geometry turns.

'round' is at 0.85 rather than 0: a Minecraft horse is boxes, so the FLAT face normal takes exactly three values on any axis and a sheen keyed to it reads as three hard zones. Blending toward the normal an ellipsoid of the same box would have is what makes it continuous.

What it paints

Each outcome, described the way the gene file describes it, and then the layers that draw it in the order they are painted. The prose is the part a reader checks a bake against; the list underneath is what the engine actually did.

Carapace Sheen

A glassy shell-sheen over the whole coat, deepest on the planes that face the light and palest underneath, with a bright line along the spine and three pale blazes on each flank.

the shell wash — PARTS × NORMAL, painted with RAMP
the ridge along the spine — PARTS × NORMAL × CENTERLINE, painted with TOWARD
and the blazes on each flank — PARTS × SPOTS, painted with TOWARD

Wild type

Nothing.

Paints nothing.