19 lines
763 B
TypeScript
19 lines
763 B
TypeScript
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// https://stackoverflow.com/questions/521295/seeding-the-random-number-generator-in-javascript/47593316#47593316
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export const LCG = (seed: number) => () =>
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((2 ** 31 - 1) & (seed = Math.imul(48271, seed))) / 2 ** 31;
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export function randomSeed() {
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return Math.floor(Math.random() * 2 ** 31);
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}
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// Unfortunately, roughjs doesn't support a seed attribute (https://github.com/pshihn/rough/issues/27).
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// We can achieve the same result by overriding the Math.random function with a
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// pseudo random generator that supports a random seed and swapping it back after.
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export function withCustomMathRandom<T>(seed: number, cb: () => T): T {
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const random = Math.random;
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Math.random = LCG(seed);
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const result = cb();
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Math.random = random;
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return result;
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}
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