interpolate method

Implementation

@override
List? interpolate(int i1, num t0, num t, num t1) {
  final result = resultBuffer,
      values = sampleValues,
      stride = valueSize,
      o1 = i1 * stride,
      o0 = o1 - stride,
      oP = _offsetPrev.toInt(),
      oN = _offsetNext.toInt(),
      wP = _weightPrev,
      wN = _weightNext,
      p = (t - t0) / (t1 - t0),
      pp = p * p,
      ppp = pp * p;

  // evaluate polynomials

  final sP = -wP * ppp + 2 * wP * pp - wP * p;
  final s0 = (1 + wP) * ppp + (-1.5 - 2 * wP) * pp + (-0.5 + wP) * p + 1;
  final s1 = (-1 - wN) * ppp + (1.5 + wN) * pp + 0.5 * p;
  final sN = wN * ppp - wN * pp;

  // combine data linearly

  for (int i = 0; i != stride; ++i) {
    result?[i] = sP * values[oP + i] +
        s0 * values[o0 + i] +
        s1 * values[o1 + i] +
        sN * values[oN + i];
  }

  return result;
}