Function createMillionPointsData

examples/million-points/main.ts:67–113

()

 * Deterministic output ensures reproducible benchmark results across runs.
 */
const createMillionPointsData = (): Readonly<{
  data: ReadonlyArray<DataPoint>;
  yMin: number;
  yMax: number;
}> => {
  const out: DataPoint[] = new Array(TOTAL_POINTS);

  // Synthetic: sine wave + low-frequency component + uniform noise.
  const freq = 0.012;
  const lowFreq = 0.0017;
  const noiseAmp = 0.35;

  // xorshift32 PRNG (deterministic, no allocations).
  let state = 0x12345678 | 0;
  const rand01 = (): number => {
    state ^= state << 13;
    state ^= state >>> 17;
    state ^= state << 5;
    // Convert to [0, 1).
    return (state >>> 0) / 4294967296;
  };

  let yMin = Number.POSITIVE_INFINITY;
  let yMax = Number.NEGATIVE_INFINITY;

  for (let i = 0; i < TOTAL_POINTS; i++) {
    const x = i;
    const y =
      Math.sin(i * freq) * 0.95 +
      Math.sin(i * lowFreq + 1.1) * 0.6 +
      (rand01() - 0.5) * noiseAmp;

    if (y < yMin) yMin = y;
    if (y > yMax) yMax = y;

    out[i] = [x, y] as const;
  }

  if (!Number.isFinite(yMin) || !Number.isFinite(yMax)) {
    yMin = -2;
    yMax = 2;
  }

  // Add a small pad to avoid touching edges.
  const pad = 0.05 * (yMax - yMin || 1);
  return { data: out, yMin: yMin - pad, yMax: yMax + pad };
};

/**
 * Zoom-aware sampling target: zooming in increases target points for detail preservation.