The flat Y the base sits at — below every piece of ground on the map.
The map currently walled. Swap with MapSkirt.setMap.
Add to a scene (or any Object3D). Returns this for chaining.
Show or hide the wall.
Point at a different map and rebuild (the base Y is re-derived from it).
Restyle, and rebuild if anything geometric changed. Options accumulate across calls, like the sky's.
Rebuild from the current map. Call after editing elevations, water, or the map's size — the perimeter is small, so this is cheap enough to do on every brush stroke rather than tracking which edge cells moved.
Detach and free the geometry (and the material, unless one was supplied).
The wall of earth that closes the map's open edges — the map as a block cut out of the world, landscape intact on top, soil strata down the sides.
Without one, a camera low enough to see the horizon also sees under the map: the terrain is a surface, not a solid, and its edges are simply where the triangles stop. The skirt gives it a bottom and four sides.
The top follows the terrain's own contour, sharing the exact perturbation the chunk builder uses, so it meets the ground with no seam — which is why the geometry options must match the ones the terrain was built with. The base is a single flat Y under the entire map, deep enough that the lowest ground still has MapSkirtOptions.depth of soil beneath it.
It follows the ground, including where the ground is a sea bed, so the cut shows a coastline honestly: soil up to the bed, then the water's own cross-section above it.
Only the perimeter is built, so this is
O(width + height)and cheap to rebuild outright — there is no chunked or streamed version and none is needed.Example