Orchestration de la génération des tuiles vectorielles

build.js

const execa = require('execa')
const bluebird = require('bluebird')
const {bboxPolygon, area} = require('@turf/turf')

const TERRITOIRES = [
  {name: 'france', bbox: [-5.53, 42.03, 8.87, 51.72]},
  {name: 'corse', bbox: [8.05, 41.26, 10.09, 43.17]},
  {name: 'reunion', bbox: [55.06, -21.47, 56.04, -20.79]},
  {name: 'martinique', bbox: [-61.47, 14.22, -60.53, 15.07]},
  {name: 'guadeloupe', bbox: [-62.07, 15.70, -60.78, 16.64]},
  {name: 'mayotte', bbox: [44.77, -13.21, 45.55, -12.47]},
  {name: 'saint-martin-saint-barthelemy', bbox: [-63.18, 17.85, -62.75, 18.13]},
  {name: 'guyane', bbox: [-54.95, 2.01, -51.26, 5.94]},
  // {name: 'saint-pierre-et-miquelon', bbox: [-56.70, 46.56, -55.87, 47.32]},
  // {name: 'nouvelle-caledonie', bbox: [161.67, -23.16, 168.59, -18.12]},
  // {name: 'polynesie-francaise', bbox: [-156.04, -29.07, -132.53, -6.75]},
  // {name: 'wallis-et-futuna', bbox: [-178.46, -14.62, -175.90, -12.88]}
]

const WORLD_MIN_ZOOM = 0
const WORLD_MAX_ZOOM = 6
const WORLD_PARTS = 8

const TERRITOIRES_MIN_ZOOM = 7
const TERRITOIRES_MAX_ZOOM = 16

const MAX_AREA_PER_PART = 50000 // 50 000 km2

// Calcule la surface de la bbox du territoire, en km2
function computeArea(territoire) {
  return area(bboxPolygon(territoire.bbox)) / 1000000
}

function computePartsNumber(territoire) {
  const area = computeArea(territoire)

  if (area < MAX_AREA_PER_PART) {
    return 1
  }

  return (area - (area % MAX_AREA_PER_PART)) / MAX_AREA_PER_PART
}

function generateTilesPart({name, bbox, minZoom, maxZoom, part, parts}) {
  part = part || 0
  parts = parts || 1
  const projectName = `${name}-${part}`

  const env = {
    MIN_ZOOM: minZoom,
    MAX_ZOOM: maxZoom,
    MBTILES_NAME: projectName + '.mbtiles',
    PART: part,
    PARTS: parts
  }

  if (bbox) {
    env.BBOX = bbox.join(',')
  }

  console.log(JSON.stringify({name, bbox, minZoom, maxZoom, part, parts}))
  return execa('docker-compose', ['run', '--rm', '--name', projectName, 'generate-vectortiles'], {env})
}

function splitInParts(options) {
  return (new Array(options.parts || 1)).fill(true).map((v, i) => ({...options, part: i}))
}

function listTilesParts() {
  const tilesParts = splitInParts({
    name: 'world',
    minZoom: WORLD_MIN_ZOOM,
    maxZoom: WORLD_MAX_ZOOM,
    parts: WORLD_PARTS
  })
  TERRITOIRES.forEach(territoire => {
    const options = {
      ...territoire,
      minZoom: TERRITOIRES_MIN_ZOOM,
      maxZoom: TERRITOIRES_MAX_ZOOM,
      parts: computePartsNumber(territoire)
    }
    splitInParts(options).forEach(part => {
      tilesParts.push(part)
    })
  })
  return tilesParts
}

async function main() {
  await bluebird.map(listTilesParts(), partOptions => generateTilesPart(partOptions), {concurrency: 8})
}

main().catch(error => {
  console.error(error)
  process.exit(1)
})