vizicities/src/layer/GeoJSONLayer.js

// TODO: Consider adopting GeoJSON CSS
// http://wiki.openstreetmap.org/wiki/Geojson_CSS

// TODO: Allow interaction to be defined per-layer to save on resources
//
// For example, only allow polygons to be interactive via a polygonInteractive
// option

import LayerGroup from './LayerGroup';
import extend from 'lodash.assign';
import reqwest from 'reqwest';
import GeoJSON from '../util/GeoJSON';
import Buffer from '../util/Buffer';
import PickingMaterial from '../engine/PickingMaterial';
import PolygonLayer from './geometry/PolygonLayer';
import PolylineLayer from './geometry/PolylineLayer';
import PointLayer from './geometry/PointLayer';

class GeoJSONLayer extends LayerGroup {
  constructor(geojson, options) {
    var defaults = {
      output: false,
      interactive: false,
      topojson: false,
      filter: null,
      layers: null,
      onEachFeature: null,
      polygonMaterial: null,
      onPolygonMesh: null,
      onPolygonBufferAttributes: null,
      polylineMaterial: null,
      onPolylineMesh: null,
      onPolylineBufferAttributes: null,
      pointGeometry: null,
      pointMaterial: null,
      onPointMesh: null,
      style: GeoJSON.defaultStyle,
      keepFeatures: true
    };

    var _options = extend({}, defaults, options);

    if (typeof options.style === 'function') {
      _options.style = options.style;
    } else {
      _options.style = extend({}, defaults.style, options.style);
    }

    super(_options);

    this._geojson = geojson;
  }

  _onAdd(world) {
    // Only add to picking mesh if this layer is controlling output
    //
    // Otherwise, assume another component will eventually add a mesh to
    // the picking scene
    if (this.isOutput()) {
      this._pickingMesh = new THREE.Object3D();
      this.addToPicking(this._pickingMesh);
    }

    // Request data from URL if needed
    if (typeof this._geojson === 'string') {
      return this._requestData(this._geojson);
    } else {
      // Process and add GeoJSON to layer
      return this._processData(this._geojson);
    }
  }

  _requestData(url) {
    return new Promise((resolve, reject) => {
      this._request = reqwest({
        url: url,
        type: 'json',
        crossOrigin: true
      }).then(res => {
        // Clear request reference
        this._request = null;
        this._processData(res).then(() => {
          resolve(this);
        });
      }).catch(err => {
        console.error(err);

        // Clear request reference
        this._request = null;

        reject(err);
      });
    });
  }

  // TODO: Wrap into a helper method so this isn't duplicated in the tiled
  // GeoJSON output layer
  //
  // Need to be careful as to not make it impossible to fork this off into a
  // worker script at a later stage
  _processData(data) {
    return new Promise((resolve) => {
      var layers = [];

      if (this._options.layers) {
        layers = this._options.layers;
      }

      // Collects features into a single FeatureCollection
      //
      // Also converts TopoJSON to GeoJSON if instructed
      this._geojson = GeoJSON.collectFeatures(data, layers, this._options.topojson);

      // TODO: Check that GeoJSON is valid / usable

      var features = this._geojson.features;

      // Run filter, if provided
      if (this._options.filter) {
        features = this._geojson.features.filter(this._options.filter);
      }

      var defaults = {};

      // Assume that a style won't be set per feature
      var style = this._options.style;

      var layerPromises = [];

      var options;
      features.forEach(feature => {
        // Get per-feature style object, if provided
        if (typeof this._options.style === 'function') {
          style = extend({}, GeoJSON.defaultStyle, this._options.style(feature));
        }

        options = extend({}, defaults, {
          // If merging feature layers, stop them outputting themselves
          // If not, let feature layers output themselves to the world
          output: !this.isOutput(),
          interactive: this._options.interactive,
          style: style
        });

        var layer = this._featureToLayer(feature, options);

        if (!layer) {
          return;
        }

        // Sometimes you don't want to store a reference to the feature
        //
        // For example, to save memory when being used by tile layers
        if (this._options.keepFeatures) {
          layer.feature = feature;
        }

        // If defined, call a function for each feature
        //
        // This is commonly used for adding event listeners from the user script
        if (this._options.onEachFeature) {
          this._options.onEachFeature(feature, layer);
        }

        // TODO: Make this a promise array and only continue on completion
        layerPromises.push(this.addLayer(layer));
      });

      Promise.all(layerPromises).then((results) => {
        // If merging layers do that now, otherwise skip as the geometry layers
        // should have already outputted themselves
        if (!this.isOutput()) {
          resolve();
          return;
        }

        // From here on we can assume that we want to merge the layers

        var polygonAttributes = [];
        var polygonOutlineAttributes = [];
        var polygonAttributeLengths = {
          positions: 3,
          normals: 3,
          colors: 3
        };
        var polygonFlat = true;

        var polylineAttributes = [];
        var polylineAttributeLengths = {
          positions: 3,
          colors: 3
        };
        var polylineFlat = true;

        var pointAttributes = [];
        var pointAttributeLengths = {
          positions: 3,
          normals: 3,
          colors: 3
        };
        var pointFlat = true;

        this._layers.forEach(layer => {
          if (layer instanceof PolygonLayer) {
            polygonAttributes.push(layer.getBufferAttributes());

            var outlineBufferAttributes = layer.getOutlineBufferAttributes();
            if (outlineBufferAttributes) {
              polygonOutlineAttributes.push(outlineBufferAttributes);
            }

            if (polygonFlat && !layer.isFlat()) {
              polygonFlat = false;
            }

            if (this._options.interactive) {
              polygonAttributeLengths.pickingIds = 1;
            }
          } else if (layer instanceof PolylineLayer) {
            polylineAttributes.push(layer.getBufferAttributes());

            if (polylineFlat && !layer.isFlat()) {
              polylineFlat = false;
            }

            if (this._options.interactive) {
              polylineAttributeLengths.pickingIds = 1;
            }
          } else if (layer instanceof PointLayer) {
            pointAttributes.push(layer.getBufferAttributes());

            if (pointFlat && !layer.isFlat()) {
              pointFlat = false;
            }

            if (this._options.interactive) {
              pointAttributeLengths.pickingIds = 1;
            }
          }
        });

        var style;

        if (polygonAttributes.length > 0) {
          var mergedPolygonAttributes = Buffer.mergeAttributes(polygonAttributes);

          var mergedPolygonOutlineAttributes;
          if (polygonOutlineAttributes.length > 0) {
            mergedPolygonOutlineAttributes = Buffer.mergeAttributes(polygonOutlineAttributes);
          }

          style = (typeof this._options.style === 'function') ? this._options.style(this._geojson.features[0]) : this._options.style;
          style = extend({}, GeoJSON.defaultStyle, style);

          this._setPolygonMesh(mergedPolygonAttributes, polygonAttributeLengths, style, polygonFlat).then((result) => {
            this._polygonMesh = result.mesh;
            this.add(this._polygonMesh);

            if (mergedPolygonOutlineAttributes) {
              style = (typeof this._options.style === 'function') ? this._options.style(this._geojson.features[0]) : this._options.style;
              style = extend({}, GeoJSON.defaultStyle, style);

              if (style.outlineRenderOrder !== undefined) {
                style.lineRenderOrder = style.outlineRenderOrder;
              } else {
                style.lineRenderOrder = (style.renderOrder) ? style.renderOrder + 1 : 4;
              }

              if (style.outlineWidth) {
                style.lineWidth = style.outlineWidth;
              }

              this._setPolylineMesh(mergedPolygonOutlineAttributes, polylineAttributeLengths, style, true).then((result) => {
                this.add(result.mesh);
              });
            }

            if (result.pickingMesh) {
              this._pickingMesh.add(result.pickingMesh);
            }
          });
        }

        if (polylineAttributes.length > 0) {
          var mergedPolylineAttributes = Buffer.mergeAttributes(polylineAttributes);

          style = (typeof this._options.style === 'function') ? this._options.style(this._geojson.features[0]) : this._options.style;
          style = extend({}, GeoJSON.defaultStyle, style);

          this._setPolylineMesh(mergedPolylineAttributes, polylineAttributeLengths, style, polylineFlat).then((result) => {
            this._polylineMesh = result.mesh;
            this.add(this._polylineMesh);

            if (result.pickingMesh) {
              this._pickingMesh.add(result.pickingMesh);
            }
          });
        }

        if (pointAttributes.length > 0) {
          var mergedPointAttributes = Buffer.mergeAttributes(pointAttributes);

          style = (typeof this._options.style === 'function') ? this._options.style(this._geojson.features[0]) : this._options.style;
          style = extend({}, GeoJSON.defaultStyle, style);

          this._setPointMesh(mergedPointAttributes, pointAttributeLengths, style, pointFlat).then((result) => {
            this._pointMesh = result.mesh;
            this.add(this._pointMesh);

            if (result.pickingMesh) {
              this._pickingMesh.add(result.pickingMesh);
            }
          });
        }

        // Clean up layers
        //
        // TODO: Are there ever situations where the unmerged buffer attributes
        // and coordinates would still be required?
        this._layers.forEach(layer => {
          layer.clearBufferAttributes();
          layer.clearCoordinates();
        });

        resolve();
      });
    });
  }

  // Create and store mesh from buffer attributes
  //
  // TODO: Probably remove this and call static method directly as it's just a proxy
  _setPolygonMesh(attributes, attributeLengths, style, flat) {
    return PolygonLayer.SetMesh(attributes, attributeLengths, flat, style, this._options, this._world._environment._skybox);
  }

  _setPolylineMesh(attributes, attributeLengths, style, flat) {
    return PolylineLayer.SetMesh(attributes, attributeLengths, flat, style, this._options);
  }

  _setPointMesh(attributes, attributeLengths, style, flat) {
    return PointLayer.SetMesh(attributes, attributeLengths, flat, style, this._options);
  }

  // TODO: Support all GeoJSON geometry types
  _featureToLayer(feature, options) {
    var geometry = feature.geometry;
    var coordinates = (geometry.coordinates) ? geometry.coordinates : null;

    if (!coordinates || !geometry) {
      return;
    }

    if (geometry.type === 'Polygon' || geometry.type === 'MultiPolygon') {
      // Get material instance to use for polygon, if provided
      if (typeof this._options.polygonMaterial === 'function') {
        options.polygonMaterial = this._options.polygonMaterial(feature);
      }

      if (typeof this._options.onPolygonMesh === 'function') {
        options.onPolygonMesh = this._options.onPolygonMesh;
      }

      // Pass onBufferAttributes callback, if defined
      if (typeof this._options.onPolygonBufferAttributes === 'function') {
        options.onBufferAttributes = this._options.onPolygonBufferAttributes;
      }

      return new PolygonLayer(coordinates, options);
    }

    if (geometry.type === 'LineString' || geometry.type === 'MultiLineString') {
      // Get material instance to use for line, if provided
      if (typeof this._options.lineMaterial === 'function') {
        options.lineMaterial = this._options.lineMaterial(feature);
      }

      if (typeof this._options.onPolylineMesh === 'function') {
        options.onPolylineMesh = this._options.onPolylineMesh;
      }

      // Pass onBufferAttributes callback, if defined
      if (typeof this._options.onPolylineBufferAttributes === 'function') {
        options.onBufferAttributes = this._options.onPolylineBufferAttributes;
      }

      return new PolylineLayer(coordinates, options);
    }

    if (geometry.type === 'Point' || geometry.type === 'MultiPoint') {
      // Get geometry object to use for point, if provided
      if (typeof this._options.pointGeometry === 'function') {
        options.pointGeometry = this._options.pointGeometry(feature);
      }

      // Get material instance to use for point, if provided
      if (typeof this._options.pointMaterial === 'function') {
        options.pointMaterial = this._options.pointMaterial(feature);
      }

      if (typeof this._options.onPointMesh === 'function') {
        options.onPointMesh = this._options.onPointMesh;
      }

      return new PointLayer(coordinates, options);
    }
  }

  _abortRequest() {
    if (!this._request) {
      return;
    }

    this._request.abort();
  }

  // Destroy the layers and remove them from the scene and memory
  destroy() {
    // Cancel any pending requests
    this._abortRequest();

    // Clear request reference
    this._request = null;

    this._geojson = null;

    if (this._pickingMesh) {
      // TODO: Properly dispose of picking mesh
      this._pickingMesh = null;
    }

    if (this._polygonMesh) {
      this._polygonMesh = null;
    }

    if (this._polylineMesh) {
      this._polylineMesh = null;
    }

    if (this._pointMesh) {
      this._pointMesh = null;
    }

    // Run common destruction logic from parent
    super.destroy();
  }
}

export default GeoJSONLayer;

var noNew = function(geojson, options) {
  return new GeoJSONLayer(geojson, options);
};

export {noNew as geoJSONLayer};