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Said TurkseverandClaude Fable 5.1
fa5710bcf2
Camera-driven Mapillary coverage (z0–5 overview points from orbit, z11–14 ground-clamped sequence lines below 60 km), per-sequence image cones, an embedded MapillaryJS viewer bridge with a camera-follow mode, sprite icons for map features, and a query engine that turns a plan into a streamed z14 tile fan-out. Registers an on-globe CC BY-SA 4.0 credit while enabled. Co-Authored-By: Claude Fable 5.1 <[email protected]>
59 lines
1.9 KiB
JavaScript
59 lines
1.9 KiB
JavaScript
import { PbfReader, PbfWriter } from 'pbf';
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/** Field number of `layers` in a Mapbox Vector Tile, and of `name` in a layer. */
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const TILE_LAYER_FIELD = 3;
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const LAYER_NAME_FIELD = 1;
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/** Read a layer's name without touching its features. */
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function layerName(layerBytes) {
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const pbf = new PbfReader(layerBytes);
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let name = '';
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pbf.readFields((tag, _result, reader) => {
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if (tag !== LAYER_NAME_FIELD) return;
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name = reader.readString();
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reader.pos = reader.length; // the name is all we need
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}, null);
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return name;
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}
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/**
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* Drop whole layers from a vector tile at the protobuf level. Nothing inside
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* a kept layer is decoded or re-encoded, so a 12 MB tile whose bulk is an
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* unused layer trims in a few milliseconds. Returns the input when nothing
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* was dropped.
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* @param {Buffer|Uint8Array} bytes
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* @param {Iterable<string>} dropNames
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*/
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export function stripTileLayers(bytes, dropNames) {
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const drop = new Set(dropNames || []);
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if (!bytes?.length || !drop.size) return bytes;
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const reader = new PbfReader(bytes);
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const writer = new PbfWriter();
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let dropped = false;
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reader.readFields((tag, _result, pbf) => {
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if (tag !== TILE_LAYER_FIELD) return; // pbf skips what we leave alone
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const end = pbf.readVarint() + pbf.pos;
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const layerBytes = bytes.subarray(pbf.pos, end);
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pbf.pos = end;
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if (drop.has(layerName(layerBytes))) {
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dropped = true;
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return;
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}
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writer.writeBytesField(TILE_LAYER_FIELD, layerBytes);
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}, null);
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return dropped ? Buffer.from(writer.finish()) : bytes;
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}
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/** Names of the layers inside a vector tile, in order. */
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export function listTileLayers(bytes) {
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const names = [];
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if (!bytes?.length) return names;
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new PbfReader(bytes).readFields((tag, _result, pbf) => {
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if (tag !== TILE_LAYER_FIELD) return;
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const end = pbf.readVarint() + pbf.pos;
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names.push(layerName(bytes.subarray(pbf.pos, end)));
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pbf.pos = end;
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}, null);
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return names;
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}
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