Triangle grid stream based on Turf.js triangle grid function.

stream-triangles.js

"use strict"
exports.__esModule = true
var distance_1 = require("@turf/distance")
var intersect_1 = require("@turf/intersect")
var helpers_1 = require("@turf/helpers")
/**
 * Takes a bounding box and a cell depth and returns a set of triangular {@link Polygon|polygons} in a grid.
 *
 * @name triangleGrid
 * @param {Array<number>} bbox extent in [minX, minY, maxX, maxY] order
 * @param {number} cellSide dimension of each cell
 * @param {Object} [options={}] Optional parameters
 * @param {string} [options.units='kilometers'] used in calculating cellSide, can be degrees, radians, miles, or kilometers
 * @param {Feature<Polygon>} [options.mask] if passed a Polygon or MultiPolygon, the grid Points will be created only inside it
 * @param {Object} [options.properties={}] passed to each point of the grid
 * @returns {FeatureCollection<Polygon>} grid of polygons
 * @example
 * var bbox = [-95, 30 ,-85, 40]
 * var cellSide = 50
 * var options = {units: 'miles'}
 *
 * var triangleGrid = turf.triangleGrid(bbox, cellSide, options)
 *
 * //addToMap
 * var addToMap = [triangleGrid]
 */

var triangleStream = null

function triangleGridStream(bbox, cellSide, options) {
  return new Promise((resolve, reject) => {
    triangleStream = triangleGridGenerator(bbox, cellSide, options)
    if (triangleStream)
      resolve(triangleStream)
    else
      reject("Failed to generate stream")
  })
}


function* triangleGridGenerator(bbox, cellSide, options) {
  if (options === void 0) { options = {} }
  // Containers
  var results = []
  // Input Validation is being handled by Typescript
  // if (cellSide === null || cellSide === undefined) throw new Error('cellSide is required')
  // if (!isNumber(cellSide)) throw new Error('cellSide is invalid')
  // if (!bbox) throw new Error('bbox is required')
  // if (!Array.isArray(bbox)) throw new Error('bbox must be array')
  // if (bbox.length !== 4) throw new Error('bbox must contain 4 numbers')
  // if (mask && ['Polygon', 'MultiPolygon'].indexOf(getType(mask)) === -1) throw new Error('options.mask must be a (Multi)Polygon')
  // Main
  var xFraction = cellSide / (distance_1["default"]([bbox[0], bbox[1]], [bbox[2], bbox[1]], options))
  var cellWidth = xFraction * (bbox[2] - bbox[0])
  var yFraction = cellSide / (distance_1["default"]([bbox[0], bbox[1]], [bbox[0], bbox[3]], options))
  var cellHeight = yFraction * (bbox[3] - bbox[1])
  var xi = 0
  var currentX = bbox[0]
  while (currentX <= bbox[2]) {
    var yi = 0
    var currentY = bbox[1]
    while (currentY <= bbox[3]) {
      var cellTriangle1 = null
      var cellTriangle2 = null
      if (xi % 2 === 0 && yi % 2 === 0) {
        cellTriangle1 = helpers_1.polygon([
          [
            [currentX, currentY],
            [currentX, currentY + cellHeight],
            [currentX + cellWidth, currentY],
            [currentX, currentY]
          ]
        ], options.properties)
        cellTriangle2 = helpers_1.polygon([
          [
            [currentX, currentY + cellHeight],
            [currentX + cellWidth, currentY + cellHeight],
            [currentX + cellWidth, currentY],
            [currentX, currentY + cellHeight]
          ]
        ], options.properties)
      } else if (xi % 2 === 0 && yi % 2 === 1) {
        cellTriangle1 = helpers_1.polygon([
          [
            [currentX, currentY],
            [currentX + cellWidth, currentY + cellHeight],
            [currentX + cellWidth, currentY],
            [currentX, currentY]
          ]
        ], options.properties)
        cellTriangle2 = helpers_1.polygon([
          [
            [currentX, currentY],
            [currentX, currentY + cellHeight],
            [currentX + cellWidth, currentY + cellHeight],
            [currentX, currentY]
          ]
        ], options.properties)
      } else if (yi % 2 === 0 && xi % 2 === 1) {
        cellTriangle1 = helpers_1.polygon([
          [
            [currentX, currentY],
            [currentX, currentY + cellHeight],
            [currentX + cellWidth, currentY + cellHeight],
            [currentX, currentY]
          ]
        ], options.properties)
        cellTriangle2 = helpers_1.polygon([
          [
            [currentX, currentY],
            [currentX + cellWidth, currentY + cellHeight],
            [currentX + cellWidth, currentY],
            [currentX, currentY]
          ]
        ], options.properties)
      } else if (yi % 2 === 1 && xi % 2 === 1) {
        cellTriangle1 = helpers_1.polygon([
          [
            [currentX, currentY],
            [currentX, currentY + cellHeight],
            [currentX + cellWidth, currentY],
            [currentX, currentY]
          ]
        ], options.properties)
        cellTriangle2 = helpers_1.polygon([
          [
            [currentX, currentY + cellHeight],
            [currentX + cellWidth, currentY + cellHeight],
            [currentX + cellWidth, currentY],
            [currentX, currentY + cellHeight]
          ]
        ], options.properties)
      }
      if (options.mask) {
        // if (intersect_1["default"](options.mask, cellTriangle1))
        // //   results.push(cellTriangle1)
        // if (intersect_1["default"](options.mask, cellTriangle2))
        //   results.push(cellTriangle2)

        cellTriangle1 = intersect_1["default"](options.mask, cellTriangle1)
        cellTriangle2 = intersect_1["default"](options.mask, cellTriangle2)
        
        if (typeof(cellTriangle1) !== 'undefined' && typeof(cellTriangle2) !== 'undefined') {
          yield [cellTriangle1, cellTriangle2]
        } else if (typeof(cellTriangle1) !== 'undefined' && typeof(cellTriangle2) === 'undefined') {
          yield [cellTriangle1]
        } else if (typeof(cellTriangle1) === 'undefined' && typeof(cellTriangle2) !== 'undefined') {
          yield [cellTriangle2]
        } else if (typeof(cellTriangle1) === 'undefined' && typeof(cellTriangle2) === 'undefined') {
          yield null
        }
      } else {
        yield [cellTriangle1, cellTriangle2]
        // results.push(cellTriangle1)
        // results.push(cellTriangle2)
      }
      currentY += cellHeight
      yi++
    }
    xi++
    currentX += cellWidth
  }
  // yield helpers_1.featureCollection([cellTriangle1,cellTriangle2])
  // return helpers_1.featureCollection(results)
}

exports["default"] = triangleGridStream