Magical gene / fields and regions

Gill Bloom

A fungal-touched marking: one or two fan-shaped patches on the barrel, each rimmed in dull gold and hollowed to a deep maroon interior spoked like the underside of a mushroom cap.

What it can come out as

Outcome	Carrying
Gill Bloom	`Gbl/Gbl`
Wild type	`Gbl/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 5,000 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
`Gbl/Gbl`	Gill Bloom	0.02% — 1 in 5,000
`n/n`	Wild type	99.98%

Its gene carrot

The file

common/src/main/resources/horsegenetics/genes/gill_bloom.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.gill_bloom`
Phase	magical — it adds signed colour in phase 3, after the pigment has resolved
Priority	280 — where it sits in the one `(priority, key)` paint order
Alleles	`Gbl` · `n`
Varies per horse	4 values drawn once off the expressing allele copy, so a foal that inherits the copy inherits the look
Built from	FAN, FRACTAL, PARTS, TOWARD

Why it is built this way

The gills are a FAN, and this gene is half the reason that mask exists. A ridged FRACTAL gives lines that fork and taper like cracks or roots; real gills all meet at one point, which is an angle around a pivot and not a noise threshold. FAN measures exactly that, and its 'spacing' being an arc length at one unit out is what makes the spokes widen as they travel - a gill fans, it does not run parallel.

One pivot, not one per patch. FAN takes a single origin, so a horse whose FRACTAL puts two patches on the barrel gets spokes radiating from the same point for both, which reads correctly on the patch nearest the pivot and as a raked comb on the other. The pivot sits at the middle of the barrel, where the patch usually lands. A per-patch pivot would need the mask to know which blob a texel is in, which nothing here measures.

The rim and the interior are two thresholds of ONE fractal on one seed, so the gold rim is always the outside of the maroon rather than a second patch that happens to overlap it.

gillSpacing is an angle in radians, not a distance: at 0.15 a full turn holds about forty spokes, which is what the underside of a cap looks like. A number that reads like a body-unit spacing puts three bars on the whole horse.

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.

Gill Bloom

One to a few fan-shaped patches across the barrel, each with a matte gold rim opening onto a deep maroon centre spoked with dark gills.

the gold rim — PARTS × FRACTAL, painted with TOWARD
the maroon interior — PARTS × FRACTAL, painted with TOWARD
and the gills spoking out of it — PARTS × FRACTAL × FAN, painted with TOWARD

Wild type

Nothing.

Paints nothing.