Magical gene / spots and rings

Scarab Dapple

Iridescent dapples over the topline, neck and face - each one a dark rim round a mid tone round a pale core, like the shell of a beetle. The legs, the croup and a patch at each shoulder stay clear of them. 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

OutcomeCarrying
Scarab DappleScb/Scb · Scb/Scc · Scb/n · Scb/Sck
Scarab Dapple, blackSck/Sck · Sck/Scc · Sck/n
Scarab Dapple, colouredScc/Scc
Wild typeScc/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 1,786 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 pairShows asHow often
Scb/ScbScarab Dapple0.002% — 1 in 50,000
Scb/SckScarab Dapple0.0027% — 1 in 37,495
Scb/SccScarab Dapple0.0027% — 1 in 37,495
Scb/nScarab Dapple0.038% — 1 in 2,632
Sck/SckScarab Dapple, black0.0027% — 1 in 37,495
Sck/SccScarab Dapple, black0.0027% — 1 in 37,495
Sck/nScarab Dapple, black0.0027% — 1 in 37,495
Scc/SccScarab Dapple, coloured0.0027% — 1 in 37,495
n/nWild type99.944%

Its gene carrot

The file

common/src/main/resources/horsegenetics/genes/scarab_dapple.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.

Keyhorsegenetics.scarab_dapple
Phasemagical — it adds signed colour in phase 3, after the pigment has resolved
Priority313 — where it sits in the one (priority, key) paint order
AllelesScb · Sck · Scc · n
Varies per horse8 values drawn once off the expressing allele copy, so a foal that inherits the copy inherits the look
Built fromAXIS, FLAT, SPOTS

Why it is built this way

Imported from the magic-gene intake, 2026-09-08. The source asked for the dapples to be cleared in a rump band and in a round patch at each shoulder, and gave the patches as circles at explicit body coordinates. There is no mask that draws a circle at a named point - SPOTS is a lattice - so the clearance here is two AXIS bands crossed instead: the barrel keeps its dapples only between x=15 and x=25.5. It reads as a saddle rather than as two roundels, which is a real difference and the one thing to look at first on a bake.

The three shells are drawn as three separate layers, largest first, each one with the next size down subtracted. Painting them the other way round would work too and would be wrong: the pale core has to go on last or the rim covers it.

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 Sck 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.

The white form was regraded at the same time. It spanned a much narrower range of lightness than the coloured form did - the same layers the coloured form separates were all landing on off-white - so its tones now follow the coloured form's own per-layer ordering, in greys. All three forms carry the same number of steps.

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.

Scarab Dapple

Dapples in three shells of near-white - a grey rim, a white ring and a core paler than either. They cover the barrel, the neck and the face; the croup, the shoulders and all four legs are left alone, so the pattern reads as a saddle of shells rather than as a coat.

  1. the dark outer rim of each dapple (barrel) — SPOTS × SPOTS inverted × AXIS × AXIS, painted with FLAT
  2. the mid tone inside the rim (barrel) — SPOTS × SPOTS inverted × AXIS × AXIS, painted with FLAT
  3. the light core of each dapple (barrel) — SPOTS × AXIS × AXIS, painted with FLAT
  4. the dark outer rim of each dapple (neck and face) — SPOTS × SPOTS inverted, painted with FLAT
  5. the mid tone inside the rim (neck and face) — SPOTS × SPOTS inverted, painted with FLAT
  6. the light core of each dapple (neck and face) — SPOTS, painted with FLAT

Scarab Dapple, black

The same marking as the white form with the light taken out of it: the same 3 steps, moved to the dark end of the scale.

  1. the dark outer rim of each dapple (barrel) — SPOTS × SPOTS inverted × AXIS × AXIS, painted with FLAT
  2. the mid tone inside the rim (barrel) — SPOTS × SPOTS inverted × AXIS × AXIS, painted with FLAT
  3. the light core of each dapple (barrel) — SPOTS × AXIS × AXIS, painted with FLAT
  4. the dark outer rim of each dapple (neck and face) — SPOTS × SPOTS inverted, painted with FLAT
  5. the mid tone inside the rim (neck and face) — SPOTS × SPOTS inverted, painted with FLAT
  6. the light core of each dapple (neck and face) — SPOTS, painted with FLAT

Scarab Dapple, coloured

The same three shells in a colour the line carries, and the shading is what makes it a beetle rather than a spot: the rim is dark, the middle is the hue itself and the core is pale. Fully recessive - it takes two copies, and one beside the pale allele shows pale.

  1. the dark outer rim of each dapple (barrel) — SPOTS × SPOTS inverted × AXIS × AXIS, painted with FLAT
  2. the mid tone inside the rim (barrel) — SPOTS × SPOTS inverted × AXIS × AXIS, painted with FLAT
  3. the light core of each dapple (barrel) — SPOTS × AXIS × AXIS, painted with FLAT
  4. the dark outer rim of each dapple (neck and face) — SPOTS × SPOTS inverted, painted with FLAT
  5. the mid tone inside the rim (neck and face) — SPOTS × SPOTS inverted, painted with FLAT
  6. the light core of each dapple (neck and face) — SPOTS, painted with FLAT

Wild type

No dapples.

Paints nothing.