Explode Mode

explode splits a multipolygon into separate single-polygon features. It is a selection-gated mode and only applies to multipolygons — select a multipolygon first (see Select Mode) and the Explode control becomes enabled. The control stays disabled for a plain Polygon, since there is nothing to split (requiresSelection context multipolygon).

When a multipolygon is exploded, the original feature is removed (gm:remove) and one new feature is created per part (gm:create).

map.gm.enableMode('edit', 'explode');
map.gm.disableMode('edit', 'explode');
map.gm.toggleMode('edit', 'explode');
map.gm.isModeEnabled('edit', 'explode');

Programmatic API

const result = await map.gm.edit.explode('subedit-polygon');

if (result.ok) {
  console.log('New features:', result.features); // one per part
} else {
  console.warn('Rejected:', result.reason); // e.g. 'no_target'
}

The following methods are available on map.gm:

Method	Returns	Description
enableMode('edit', 'explode')	Promise	Enables Explode Mode.
disableMode('edit', 'explode')	Promise	Disables Explode Mode.
toggleMode('edit', 'explode')	Promise	Toggles Explode Mode.
isModeEnabled('edit', 'explode')	Boolean	Returns true if Explode Mode is enabled. false when disabled.

The following events are available on a map instance:

Event	Params	Description	Output
gm:explode	event	Fired when a multipolygon is exploded.	map, features, shape
gm:create	event	Fired for each new single-polygon feature created.	map, feature, shape
gm:remove	event	Fired when the original multipolygon is removed.	map, feature, shape

map.on('gm:explode', (event) => {
  console.log('Exploded into:', event.features?.map((f) => f.id));
});

Live Explode Example

This feature is a two-part multipolygon. Click it to select it, then activate Explode to split it into two independent polygons.

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