isGlobeViewport

isGlobeViewport(viewport) returns true when a deck.gl viewport draws a 3D globe. This is a GlobeView below zoom 12. Above zoom 12, GlobeView uses a Web Mercator viewport, and the function returns false.

import {isGlobeViewport} from '@deck.gl-community/geo-layers';

const geographic = isGlobeViewport(this.context.viewport);

Why not viewport.resolution

In deck.gl 9.4, only GlobeViewport sets resolution. deck.gl v10 makes resolution the subdivision detail of every viewport and sets it to 0 by default, GlobeView included. A truthiness test of resolution then reads every globe as a flat map.

isGlobeViewport compares viewport.projectionMode with deck.gl's PROJECTION_MODE.GLOBE (2). Every deck.gl 9.4 and v10 viewport defines projectionMode. When an object has no numeric projectionMode, the function falls back to instanceof GlobeViewport.