Magical gene / lines and strokes

Emberveins

Fine seams trace the coat like cracked stone about to give way - molten orange in the glowing form, a quiet rust vein-work in the other - with drifting embers and one wandering thread of light caught along the flank.

What it can come out as

Outcome	Carrying
Emberveins, glowing	`Emb/Emb` · `Emb/Emr` · `Emb/n`
Emberveins, rust	`Emr/Emr`
Wild type	`Emr/n` · `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 7,143 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
`Emb/Emb`	Emberveins, glowing	0.0005% — 1 in 200,000
`Emb/Emr`	Emberveins, glowing	0.002% — 1 in 50,000
`Emb/n`	Emberveins, glowing	0.0095% — 1 in 10,526
`Emr/Emr`	Emberveins, rust	0.002% — 1 in 50,000
`n/n`	Wild type	99.986%

Its gene carrot

The file

common/src/main/resources/horsegenetics/genes/emberveins.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.emberveins`
Phase	magical — it adds signed colour in phase 3, after the pigment has resolved
Priority	383 — where it sits in the one `(priority, key)` paint order
Alleles	`Emb` · `Emr` · `n`
Varies per horse	10 values drawn once off the expressing allele copy, so a foal that inherits the copy inherits the look
Built from	CRACKLE, FRACTAL, PARTS, SPOTS, TOWARD, emissive

Why it is built this way

'vertexWeight' on the CRACKLE mask exists because of this gene. A crack read purely as distance-to-wall is a channel of EVEN width - that is what a distance to a plane is - and the reference's veins pool where cracks meet and thin to a hairline between the junctions. Blending in the distance to the three-way corners is what lets one threshold do both, and no arrangement of the other masks reaches it: SPOTS and DAPPLES measure to a cell's centre and know nothing about where its corners fell.

Both alleles draw the identical geometry from the same three seeds, so littermates of either genotype share a recognisable vein layout and only the paint differs. The recessive filament is fainter rather than absent - the same creature with the light turned down.

The reference image's three broad tones are the horse's base coat showing through the cracks, not part of this marking. It draws the network, the embers and the filament, and nothing else.

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.

Emberveins, glowing

Molten seams glow along the coat wherever the hide would naturally crease, brightest at a scatter of ember points and one thin drifting thread of light across the flank.

the vein network — PARTS × CRACKLE inverted, painted with TOWARD, and it glows
embers scattered along it — PARTS × SPOTS, painted with TOWARD, and it glows
and one thread of light along the flank — PARTS × FRACTAL, painted with TOWARD, and it glows

Emberveins, rust

The same cracked seams as quiet rust-dark vein-work, with a scatter of ash-dark freckling and one faint hairline on the flank - no glow to any of it.

the vein network — PARTS × CRACKLE inverted, painted with TOWARD
embers scattered along it — PARTS × SPOTS, painted with TOWARD
and one thread of light along the flank — PARTS × FRACTAL, painted with TOWARD

Wild type

Nothing.

Paints nothing.