GeoJSON Vector Tiling

GeoJSONVectorTileDataSource turns app-owned GeoJSON into vector tiles a VectorTileLayer styles with CartoCSS — so routes, tracks and result sets get the same renderer, styling and terrain draping as the base map, instead of the VectorLayer element path.

Fork feature

The source exists upstream; the fork rebuilt its tiler on geojson-vt (PR #54) — a real tile pyramid instead of a per-tile scan of every feature.

5000 short routes (165k points) served from one GeoJSONVectorTileDataSource, tiled at runtime and styled with CartoCSS over the base map and 3D terrain. Captured at z12.6, tilt 60.

Usage

import com.massifmaps.datasources.GeoJSONVectorTileDataSource
import com.massifmaps.layers.VectorTileLayer

val source = GeoJSONVectorTileDataSource(0, 24).apply {
    simplifyTolerance = 1.0f      // tile pixels
    defaultLayerBuffer = 4f       // FRACTION of a tile, not pixels (see below)
}

val routes = source.createLayer("routes")          // returns the layer index
source.setLayerGeoJSONString(routes, geoJsonText)  // or setLayerGeoJSON(Variant) / setLayerFeatureCollection

mapView.layers.add(VectorTileLayer(source, MBVectorTileDecoder(styleSet)))

With the surface API

// The source re-tiles whatever it is given, so an update is one call rather than a rebuild.
MassifSource tour = map.source("tour-data", Spec.of("geojson").set("maxZoom", 14));
int layer = tour.createLayer("tour");
tour.setLayerGeoJSON(layer, routeGeoJson);

map.addLayer("tour", Spec.of("vector")
    .set("source", "tour-data")
    .set("style", "route-style"));

addFeature, updateFeature and removeFeature are reachable the same way, so incremental edits need no object-API access either. Runnable, on three platforms: the GeoJSON line example.

Style it by layer name, like any other vector source:

#routes { line-color: #3388ff; line-width: 5; line-join: round; line-cap: round; }

Method	Does
createLayer(name) / deleteLayer(index)	add / drop a named layer
setLayerGeoJSON / setLayerGeoJSONString	replace a layer's whole content
setLayerFeatureCollection(index, projection, collection)	replace it from SDK geometry
addGeoJSONFeature / updateGeoJSONFeature / removeGeoJSONFeature	incremental edits (also …StringFeature)
SimplifyTolerance	Douglas-Peucker tolerance, in tile pixels
DefaultLayerBuffer	tile overflow, as a fraction of a tile (default 4)

The layer buffer is a fraction of a tile

DefaultLayerBuffer is a fraction of a tile, not pixels as older doc comments said. 64 wraps the internal uint16 to zero.

Why it changed

The old tiler scanned every feature of a layer for every tile, and kept one re-simplified copy of the dataset per zoom level. Long lines were the worst case: re-clipped from full resolution on every tile they touched. The geojson-vt pyramid clips once per level from the parent.

Measured on a device (Adreno 610), 640 tiles z8–z17:

Dataset	Before	After
8 routes of 100–250 km (303k points)	1709 ms	513 ms
5000 short routes (165k points)	1319 ms	1176 ms

Known regression, documented rather than fixed: many small features at a single zoom are 1.6× slower (209 → 328 ms over 256 tiles at z14).

Binary cost: +104 KiB on libmassif.so (arm64-v8a, stripped) — header-only template instantiation, nothing new linked.

See also

• Navigation Maneuver Arrows — built on this source.
• 3D Terrain — tiled GeoJSON drapes with the rest of the map.