pathNetwork.ground

The ground a path network stands on: the Terrain entities under it, the height the ground had before any path changed it, and the conforming of the ground to the paths. Each footprint (an edge's cross-sections, or a junction's disc) holds the ground level with its surface out to the shoulder, then blends it back over the falloff band. The ground between texels is flat triangles, each a blend of its three corner texels, so wherever a ground triangle would stand less than bed under a flat triangle of a surface over it (along the low edge of a banked road, in a sag, where a road twists onto a junction) its corners are lowered until it stands bed under. The corners under the surface go first, where the surface hides them, each no deeper than shows beside the surface by more than the triangle stood over it; the corners beside the surface carry what is left. The ground stays under the surface at any bank, grade or twist, and level with the surface along its edges. At a corner of a surface's outline (the low corner of a banked road's end) a ground cell spans both sides of the corner, and the ground beside the corner dips under the surface's edge there. A texel is judged against every footprint near it, so where paths overlap the one holding it most strongly wins, and a texel no path holds any more is given back its own height. Writes go through Terrain:setHeights, which rebuilds the drawn ground and the collision tiles the change reaches.

Function
open(terrains)	The ground state for the named terrains (or every Terrain in the scene).
present(state)	Whether any terrain has loaded.
stale(state) / settle(state)	Whether a terrain holds ground the network has not conformed (loaded since, or read again from its asset), and recording the ground as conformed.
baseHeight(state, x, z) / height(state, x, z)	The ground before the network changed it, and as it stands now.
edgeFootprint(sections, opts) / discFootprint(cx, cz, radius, y, ring, opts)	Footprints: an edge's cross-sections, or a junction's fan.
conform(state, changed, all)	Conform the area the changed footprints reach.
restore(state)	Give back every height the network changed.