Magical gene / fields and regions

Papillon

A butterfly's wing laid over the neck, drawn from a real species, with the mane and tail carrying the wing's brightest and darkest colours down their length.

What it can come out as

Outcome	Carrying
Spotty Papillon	`Sp/Sp` · `Gr/Sp`
Gradient Papillon	`Gr/Gr` · `Si/Gr`
Simple Papillon	`Si/Si` · `Si/Sp`
Wild type	`Si/n` · `Gr/n` · `Sp/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 3,571 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
`Si/Si`	Simple Papillon	0.02% — 1 in 5,000
`Si/Gr`	Gradient Papillon	0.0016% — 1 in 62,500
`Si/Sp`	Simple Papillon	0.0016% — 1 in 62,500
`Gr/Gr`	Gradient Papillon	0.0016% — 1 in 62,500
`Gr/Sp`	Spotty Papillon	0.0016% — 1 in 62,500
`Sp/Sp`	Spotty Papillon	0.0016% — 1 in 62,500
`n/n`	Wild type	99.972%

Its gene carrot

The file

common/src/main/resources/horsegenetics/genes/papillon.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.papillon`
Phase	magical — it adds signed colour in phase 3, after the pigment has resolved
Priority	268 — where it sits in the one `(priority, key)` paint order
Alleles	`Si` · `Gr` · `Sp` · `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	AXIS, PALETTE, PARTS, PATCHES, RAMP, RINGS, SPOTS, TOWARD

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.

Spotty Papillon

The wing breaks up into spotting toward its lower edge rather than ending as a field - the pattern is still the wing's, but read through a scatter of it.

the wing field over the neck — PARTS × PATCHES × SPOTS, painted with PALETTE
the eyespots and veins in it — RINGS × PATCHES, painted with TOWARD
the wing's colours running down the mane and tail — PARTS, painted with RAMP

Gradient Papillon

The wing fades into the neck's own colour as it descends, brightest at the crest and gone by the throat - blended rather than bounded, and the subtler of the two shaped forms.

the wing field over the neck — PARTS × PATCHES × AXIS, painted with PALETTE
the eyespots and veins in it — RINGS × PATCHES, painted with TOWARD
the wing's colours running down the mane and tail — PARTS, painted with RAMP

Simple Papillon

The wing pattern and the hair colouring, and nothing else - no gradient, no spotting. A clean graphic wing on the neck, and the cleanest of the three to read.

the wing field over the neck — PARTS × PATCHES, painted with PALETTE
the eyespots and veins in it — RINGS × PATCHES, painted with TOWARD
the wing's colours running down the mane and tail — PARTS, painted with RAMP

Wild type

No wing. The pattern is famously fragile: bred to horses without it, it weakens and is gone within a couple of generations.

Paints nothing.