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GlobalGrid

Purpose​

GlobalGrid defines the shared interface that the GlobalGridLayer expects when it works with Discrete Global Grid System (DGGS) helpers. Implementations expose common capabilities—converting between string tokens and numeric cell identifiers, retrieving center coordinates, and generating boundary polygons—so different grid systems can be rendered with the same layer contract.

Usage​

Implement the GlobalGrid contract when wiring up a custom DGGS helper:

import type {GlobalGrid} from '@deck.gl/geo-layers';
import {GlobalGridLayer} from '@deck.gl/geo-layers';

const CustomGrid: GlobalGrid = {
  name: 'custom',
  hasNumericRepresentation: false,
  cellToLngLat: cell => lookupCenter(cell),
  cellToBoundary: cell => lookupBoundary(cell)
};

const layer = new GlobalGridLayer({
  id: 'custom-grid',
  data: dataset,
  globalGrid: CustomGrid,
  getCellId: d => d.cellId
});

Every optional method on the interface—such as initialize, tokenToCell, cellToToken, or lngLatToCell—can be supplied when a grid supports those operations. The layer automatically calls globalGrid.initialize() during initializeState and uses cellToBoundary to build the polygon geometry.

Shared conventions​

  • cellToLngLat must return an array [longitude, latitude].
  • cellToBoundary must return an array of [longitude, latitude] vertices; the layer will append the first vertex to close the polygon.
  • hasNumericRepresentation communicates whether a bigint representation is available alongside the string token.
  • GlobalGridLayer reads the DGGS identifier through getCellId (defaulting to the cellId property) and forwards the value directly to the helper.

Refer to the specific helper pages below for grid-specific behavior and caveats.