• Trace a single streamline through grid starting at the seed point, using 4th-order Runge-Kutta with unit-speed integration (velocity normalised at each sub-step). Unit-speed keeps streamlines a similar length whether they're in fast or slow regions, which reads better as a static visual — the local speed is preserved per-vertex for the colour mapping.

    Returns a flat Float32Array of [x0, y0, z0, speed0, x1, y1, z1, speed1, …] — 4 floats per vertex, the speed used for colour-by-magnitude. Empty array means the seed point lies outside the field or stalled immediately. Pure helper; never errors.

    Parameters

    Returns Float32Array