webdggrid / unwrapAntimeridianRing

Function: unwrapAntimeridianRing()

unwrapAntimeridianRing(ring): Position[]

Defined in: webdggrid.ts:202

Rewraps a polygon ring that crosses the antimeridian so that all longitudes are in a contiguous range. The output longitudes may fall outside [-180, 180] — that's intentional, and is the format expected by MapLibre GL / Mapbox GL globe projection for antimeridian cells. For renderers that require standard [-180, 180] coordinates, run a final modulo step downstream.

Walks consecutive vertices and accumulates a ±360 offset whenever the longitude delta between neighbours exceeds 180° (the only meaningful sign of an antimeridian crossing). This keeps the traversal direction faithful even for polar caps, which span a full 360° in lon and were broken by the previous "negative-to-positive" rewrite.

Parameters

ring

Position[]

Returns

Position[]