Automatically generate feature id values for geojson & cluster sources

[ryanbaumann]

Motivation

Examples using map.setFeatureState() like this https://www.mapbox.com/mapbox-gl-js/example/hover-styles/ require that a user include an integer parent id value in their geojson or vector tile source.

Design Alternatives

• Create more documentation about parent id requirement to use featureStates

Design

• Automatically generate parent a id value for a geojson source in geojson-vt, so that all geojson source features support featureStates.

• Automatically generate a parent id for clustered geojson datasources

• Not sure if a similar approach is possible for vector tile sources.

Mock-Up

Geojson-vt auto-generates feature id values for geojson and cluster sources.

Concepts

• Vector tile id values
• The difference between how vector tile sources and geojson sources are created and how they support featureStates.

[andrewharvey]

👍 There's a discussion around this over at #6019

[ryanbaumann]

Thanks, @andrewharvey! Open to feedback about whether to close ticket then and re-open a docs-focused ticket that details how to create id values for features to use with feature states.

[asheemmamoowala]

Depends on geojson-vt#109 and supercluster#94.