Seed and Recipe

A Tool is one of the six things tirage draws: sonar, husk, vein, aura, kiosk or frond. Each is named by the slug of its page on the site it reproduces. A Tool has Parameters, one per slider, toggle or picker on that page, with the same id and the same range as the control there. It paints with a Palette, an ordered list of inks. Its own random draws start from a Tool seed, the integer you would type into the seed box on that page.

A Recipe is a Tool, a value for each of its Parameters, a Palette and a Tool seed. That is everything a render needs, so a Recipe fully determines one Visual.

tirage derive prints a Recipe as one line of JSON:

tirage derive --seed 42 --tool sonar

Spread over lines, Seed 42 gives sonar this Recipe:

{
  "tirage": 0,
  "tool": "sonar",
  "tool_seed": 4243409203,
  "palette": ["#0a0f1c", "#3ddc97", "#4361ee", "#ffd166", "#ef476f", "#f1faee"],
  "params": {
    "level": 0.64,
    "scale": 6.3,
    "warp": 0.14,
    "grid": 286,
    "depth": 0.58,
    "fringe": 0.68,
    "spark": 0.09,
    "ditherTog": false,
    "dthKinds": "Bayer 8",
    "dthSize": 2,
    "dthLevels": 3,
    "dthAmount": 1.0,
    "grainTog": false,
    "grnBlends": "Add",
    "grnAmount": 0.55,
    "grnSize": 1.0,
    "grnSpecks": 0.5,
    "grnVignette": 0.5
  }
}

tirage render reads that JSON and draws it. The Seed is not in it: once the Recipe exists, the Seed has done its job. The tirage field is the derivation major, explained below.

From Seed to Recipe

A Seed is one unsigned 64-bit integer. It derives a whole Recipe, and the same Seed with the same Pins always gives the same Recipe.

Each field is drawn on its own. A draw hashes the Seed together with the name of what it is for: sonar’s level comes from the Seed, the word sonar and the word level, mapped into that Parameter’s Taste bounds. No draw reads another draw. Adding a Parameter to a Tool, or listing its Parameters in another order, leaves every existing value where it was.

Two things are not drawn. The Palette is the Tool’s default unless you pin one. The grain and dither Parameters stay at the site’s defaults, both off, unless you pin them.

The Tool seed is drawn the same way and is never 0, because the site reads a seed of 0 as 1.

Which Tool a Seed gets

With no Tool pinned, each Tool hashes the Seed with its own slug and the highest hash wins. The order Tools are registered in plays no part. Adding a seventh Tool moves only the Seeds the new Tool wins, about one in seven. The other six sevenths keep their Tool.

Seed 42 deals kiosk. Pin sonar with --tool sonar and the same Seed gives the Recipe above, with every Parameter drawn as if sonar had won.

What stays fixed

Seed to Recipe is stable within a derivation major. The major is the tirage field of the JSON. tirage --version prints the crate version and then the derivation major in brackets:

tirage --version

Any change that would hand some Seed a different Recipe bumps the major. A build refuses a Recipe written under another major and asks you to derive it again from its Seed. Until 1.0 the major stays at 0 while the derivation settles. From 1.0 on, every change to it bumps the major.

Pixels are not promised. Rendering can change within a major when a Tool moves closer to the output of its site page, so a Seed’s Visual may shift a little while its Recipe stays the same.