@open-rgs/scatters

The trigger rate is a parameter, not an emergent property.

Declared, not discovered

With a natural scatter the trigger rate emerges from per-cell probability and grid size, and you tune it by guessing a weight and re-simulating. Draw the board with the scatter at weight zero and spawn instead, and the count distribution becomes the trigger rate.

The count distribution is declared, so the trigger rate is written down.

import { withScatters, oneInFor, probabilityOfAtLeast } from "@open-rgs/scatters";

const config = {
  symbol: "SC",
  count:  { 0: 9000, 1: 700, 2: 250, 3: 45, 4: 5 },
};

oneInFor(config, 3);
probabilityOfAtLeast(config, 3);

One per reel, and which reels

At most one per reel is the genre norm, and it is what makes the count distribution exactly controllable. Excluded reels never receive one.

At most one per reel by default; excluded reels never receive one.

const config = {
  symbol:     "SC",
  count:      { 0: 9000, 1: 700, 2: 250, 3: 45, 4: 5 },
  reels:      [1, 2, 3],
  onePerReel: true,
};

const board = withScatters(reels, config);

Protected symbols stay

A wild the player can see is about to pay must not be eaten. If protections leave too few legal cells, the spawn places what it can and reports both numbers - throwing would crash a legitimate spin, and silence would break the declared rate with nothing to notice it.

Protected symbols are never eaten - a wild about to pay stays put.

import { spawnOn, assertFeasible } from "@open-rgs/scatters";

const result = spawnOn(grid, { ...config, protects: ["WILD"] }, host.rng_next);

result.wanted;
result.spawned;

assertFeasible(config, 5);