pathNetwork.geometry

The shape of a path network, as pure functions over plain tables: the centreline of an edge through its control points (a Catmull-Rom curve whose end tangents are shared with the next edge across a node), the cross-sections along it (position, heading, bank, the surface's right and up), and the meshes pathNetwork stands on entities: an edge's surface with side walls and end caps, and a junction's surface fanned out to the ends of the edges meeting there, sharing their vertices.

Function
centreline(control, before, after, step)	Sample a curve through the control points finely enough to measure it.
at(line, d)	The point a distance along a sampled centreline.
sections(line, spec)	Cross-sections between two distances, each with its surface frame; an end tips onto a plane (startPlane / endPlane) with its cross slope turning no faster than maxTwist per metre, and a twisting stretch gets sections added until the drawn triangles stand within tolerance of the surface.
smooth(ys, window, opts)	A moving-average elevation profile, its window full and centred on each sample (lead and trail samples of ground past the ends), each held end meeting the height and grade given through a cubic ease that adds no more than maxGrade and bends the grade no faster than maxBend per metre.
edgeMesh(sections, opts) / junctionMesh(centre, ends, opts)	Geometry for renderer.mesh.create.
project(a, b, x, z) / surfaceHeight(a, b, t, lateral)	Where a point lies against a segment, and the surface's height there.
fanHeight(centre, ring, x, z) / fanDistance(centre, ring, x, z)	A junction surface's height over a point, and how far outside its outline the point stands.
corner(section, side)	A surface edge of a cross-section (side -1 left, 1 right).