All extensions

@open-rgs/meters

Collect five of these and something happens.

The counter under the fisherman, the coin meter, the bar that fills across a feature. It is bookkeeping, which is exactly why it belongs in one place: every bug in it is about when, not what.

One spin can cross two thresholds

A spin that collects three at once passes every threshold in between, and each one pays, in ascending order. Awarding only the highest is the common bug, and it stays invisible until someone reconciles a big spin against the paytable.

import { meter, collect } from "@open-rgs/meters";

const CFG = {
  thresholds: [{ at: 3, award: "MINI" }, { at: 6, award: "MINOR" }, { at: 10, award: "MAJOR" }],
};

let m = meter();
const { meter: next, awards } = collect(m, 7, CFG);   // ["MINI", "MINOR"]

A threshold never fires twice, because what has been awarded is part of the meter rather than something the caller has to remember.

Filling it keeps the remainder

Under repeat, a spin that overshoots the top starts the next lap with what was left over, and a remainder that already reaches the first threshold pays it straight away: the player collected those symbols, so making them wait for a spin that adds nothing would be losing a prize.

const REPEAT = { ...CFG, repeat: true };

collect(meter(), 13, REPEAT);
// awards: MINI, MINOR, MAJOR, then MINI again on the carried 3
// meter:  { count: 3, awarded: [3], laps: 1 }

What a client shows

import { toNext, progress, isFull } from "@open-rgs/meters";

toNext(m, CFG);      // symbols to the next threshold
progress(m, CFG);    // 0..1 between the last threshold and the next, for the bar
isFull(m, CFG);      // every threshold awarded

The cadence is arithmetic

A meter at 10 that collects 0.4 per spin on average fills in 25 spins, so a ten-spin feature fills it about four times in ten. That is worth knowing before a simulation, because it is the number you are actually choosing when you set the threshold.

import { spinsToFill } from "@open-rgs/meters";

spinsToFill(CFG, 0.4);   // 25