landxml/lib/surface.js

import { getProp, parseSequence, getColor } from './util'
import { polygon } from '@turf/helpers';
import union from '@turf/union';
import proj4 from 'proj4';

export const LANDXML_SURFACE = 'surface';

export function convertSurfaces(xmlObj, projection, opts) {

  const features = [];

  const surfacesContainerNodes = getProp(xmlObj, "LandXML", "Surfaces");

  if (!surfacesContainerNodes) return features;

  surfacesContainerNodes.forEach(sc => {

    const attrs = (sc.$ || {});

    const baseProps = {
      name: attrs.name || "",
      description: attrs.desc,
    };

    const surfaceNodes = getProp(sc, "Surface");
    if (!Array.isArray(surfaceNodes)) return;

    surfaceNodes.forEach(s => {

      const name = baseProps.name ?  ( baseProps.name + ' - ' + s.$.name ) : s.$.name;
      const description = baseProps.description ? ( baseProps.description + ' - ' + s.$.desc ) : s.$.desc;
      const featureProps = {
        name: name,
        description: description,
        landxmlType: LANDXML_SURFACE,
        landxmlColor: getColor(`surface-${name}`, opts.colorOpts),
      };

      let surfaceFeatures = convertBoundaries(s, projection, featureProps, opts);

      if (surfaceFeatures.length !== 0) {
        features.push(...surfaceFeatures);
      } else {
        surfaceFeatures = convertFaces(s, projection, featureProps, opts);

        let merged = surfaceFeatures[0];

        console.error("Applying union to %s faces (%d faces to merge)", merged.properties.name, surfaceFeatures.length);

        for (let i = 1; i < surfaceFeatures.length-1; i++) {
          const next = surfaceFeatures[i+1];
          if (!next) return;
          try {
            merged = union(merged, next);
          } catch(err) {
            console.error("--> Could not apply union to %s (#%d)", next.properties.name, i+1);
            // Ignore
          }
        }

        merged.properties = featureProps;

        features.push(merged);

      }
      
    });

  });

  return features;

}

function convertFaces(surface, projection, featureProps, opts) {

  const pointNodes = getProp(surface, "Definition", 0, "Pnts", 0, "P");
  const faceNodes = getProp(surface, "Definition", 0, "Faces", 0, "F");

  const points = {};

  pointNodes.forEach(p => {
    let pointCoords = parseSequence(p._).map(v => parseFloat(v));
    pointCoords = [pointCoords[1], pointCoords[0]];
    pointCoords = proj4(projection, 'WGS84', pointCoords);
    const pointId = p.$.id;
    points[pointId] = { name: p.$.name, coords: pointCoords };
  });

  const faces = [];
  faceNodes.forEach(f => {
    const pointIds = parseSequence(f);
    const coords = [];
    pointIds.forEach(id => {
      const p = points[id];
      coords.push(p.coords);
    });
    coords.push(points[pointIds[0]].coords);
    faces.push(polygon([coords], featureProps));
  });

  return [...faces];

}

function convertBoundaries(surface, projection, featureProps, opts) {
  const boundaryNodes = getProp(surface, "SourceData", 0, "Boundaries", 0, "Boundary");

  if (!boundaryNodes) return [];

  const polygons = [];
  boundaryNodes.forEach(boundary => {
    const pntList3DNode = getProp(boundary, 'PntList3D', 0);
    const seq = parseSequence(pntList3DNode).map(p => parseFloat(p));
    const coords = [];
    for (let i = 0; i < seq.length; i += 3) {
      let c = [seq[i+1], seq[i]];
      c = proj4(projection, 'WGS84', c);
      coords.push(c);
    }
    coords.push(coords[0]);
    polygons.push(polygon([coords], featureProps));
  });

  return polygons;

}