Interface SplineCarveSpline

Center-line [x, surfaceY, z] points (absolute world; for a river, surfaceY is the intended WATER surface — the bed lands depth below it). Ordered source → mouth.

Full channel width (m) — ground inside it reaches the full profile.

Bank falloff band (m) beyond the channel half-width, feathering back to the existing terrain.

Bed depth (m) below each point's surfaceY. Use 0 with flatten for a road bed at the spline height itself.

Target subdivided link length (m). Default 6.