Magical gene / fields and regions

Iris Bloom Diamonds

Dark royal-blue diamonds unfold across the barrel like a fan of iris petals, each rimmed in ink, dappled white, and lit at the middle by radiating amber veins.

What it can come out as

Outcome	Carrying
Iris Bloom Diamonds	`Ibd/Ibd` · `Ibd/n`
Wild type	`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 20,000 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
`Ibd/Ibd`	Iris Bloom Diamonds	0.0003% — 1 in 400,000
`Ibd/n`	Iris Bloom Diamonds	0.0048% — 1 in 21,053
`n/n`	Wild type	99.995%

Its gene carrot

The file

common/src/main/resources/horsegenetics/genes/iris_bloom_diamonds.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.iris_bloom_diamonds`
Phase	magical — it adds signed colour in phase 3, after the pigment has resolved
Priority	281 — where it sits in the one `(priority, key)` paint order
Alleles	`Ibd` · `n`
Varies per horse	8 values drawn once off the expressing allele copy, so a foal that inherits the copy inherits the look
Built from	CRACKLE, FRACTAL, PARTS, SPECKLE, TOWARD

Why it is built this way

The import bet that a CRACKLE and a SPOTS mask given the same seed and spacing would agree about where a cell's centre is, and wrote a note saying it was a bet. It was a bad one - the two masks derive their points differently and the white dapple field would have drifted off the diamond it belonged to on some horses. CRACKLE now reads its own tessellation from the middle out ('measure': 'centroid'), so the amber core is GUARANTEED concentric with the rim, on the same seed and the same scale, rather than concentric by coincidence.

The outline and the fill are two readings of one wall distance, subtracted, so the ink rim can never open a seam or double-paint against the blue it edges.

The diamonds are CRACKLE rather than SPOTS because they have straight sides. CRACKLE and WAVES are the only two masks in the vocabulary that do; everything else rounds off.

'scale' is per-dose - 5 units on one copy, 3 on two - so a homozygote carries a denser fan of smaller diamonds. That is legal here because the expression claims combinations with different copy counts of the first allele; it would be a silent constant if it did not.

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.

Iris Bloom Diamonds

Dark royal-blue diamonds spread across the barrel, denser and smaller with a second copy. Each is rimmed in near-black, dappled white through its outer half, and lit at the middle by radiating amber veins.

the blue of each diamond — PARTS × CRACKLE, painted with TOWARD
the ink rim round it — PARTS × CRACKLE × CRACKLE, painted with TOWARD
white dapples over the outer half — PARTS × CRACKLE × CRACKLE inverted × SPECKLE, painted with TOWARD
and the amber veins at the middle — PARTS × CRACKLE × CRACKLE inverted × FRACTAL, painted with TOWARD

Wild type

Nothing.

Paints nothing.