Magical gene / lines and strokes

Riblines

Thin white strokes following the skeleton - down the neck, along the rib arcs, over the scapula and hip - and set as rings around the legs. A third allele carries the same marking worked in greys instead of white - dark where the pale form is light, and the same number of steps.

What it can come out as

Outcome	Carrying
Riblines	`Rib/Rib` · `Rib/Rbc` · `Rib/n` · `Rib/Rbk`
Black riblines	`Rbk/Rbk` · `Rbk/Rbc` · `Rbk/n`
Coloured riblines	`Rbc/Rbc`
Wild type	`Rbc/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 893 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
`Rib/Rib`	Riblines	0.004% — 1 in 25,000
`Rib/Rbk`	Riblines	0.0053% — 1 in 18,751
`Rib/Rbc`	Riblines	0.0053% — 1 in 18,751
`Rib/n`	Riblines	0.076% — 1 in 1,316
`Rbk/Rbk`	Black riblines	0.0053% — 1 in 18,751
`Rbk/Rbc`	Black riblines	0.0053% — 1 in 18,751
`Rbk/n`	Black riblines	0.0053% — 1 in 18,751
`Rbc/Rbc`	Coloured riblines	0.0053% — 1 in 18,751
`n/n`	Wild type	99.888%

Its gene carrot

The file

common/src/main/resources/horsegenetics/genes/riblines.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.riblines`
Phase	magical — it adds signed colour in phase 3, after the pigment has resolved
Priority	363 — where it sits in the one `(priority, key)` paint order
Alleles	`Rib` · `Rbk` · `Rbc` · `n`
Varies per horse	3 values drawn once off the expressing allele copy, so a foal that inherits the copy inherits the look
Built from	AXIS, STROKES, TOWARD

Why it is built this way

The black allele is the white one with the light taken out of it, and it sits one rung under white in the dominance series - so every combination that existed before it keeps the outcome it had, and only the pairs carrying Rbk are new. The re-toning is a mapping rather than a repaint: every achromatic target moves into the dark end of the scale keeping its order and its spacing, and every SATURATED one is left alone, because that colour is the gene rather than its lightness.

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.

Riblines

Sharp-edged white strokes that taper to points at both ends and hold one value along their whole length - no gradient inside a stroke. They run dorso-ventrally on the neck, along the rib arcs on the barrel, down the scapular spine, out from the point of hip, and around the legs rather than along them. Twenty to fifty a side, parallel within a zone and turning as the zone does.

strokes down the neck and along the ribs — STROKES, painted with TOWARD
rings set around the legs — STROKES × AXIS, painted with TOWARD

Black riblines

The same marking as the white form with the light taken out of it: a single near-black tone.

strokes down the neck and along the ribs — STROKES, painted with TOWARD
rings set around the legs — STROKES × AXIS, painted with TOWARD

Coloured riblines

The same lines, in a colour the line of horses carries rather than in white. Fully recessive - it takes two copies, and a single copy beside the white allele shows white. It never gives blue eyes; the white form may.

coloured strokes down the neck and along the ribs — STROKES, painted with TOWARD
coloured rings set around the legs — STROKES × AXIS, painted with TOWARD

Wild type

No riblines.

Paints nothing.