mapserver/public/js/map/overlays/MinecartOverlay.js

import wsChannel from '../../WebSocketChannel.js';
import layerMgr from '../../LayerManager.js';

let minecarts = [];

//update minecarts all the time
wsChannel.addListener("minetest-info", function(info){
  minecarts = info.minecarts || [];
});


export default L.LayerGroup.extend({
  initialize: function() {
    L.LayerGroup.prototype.initialize.call(this);

    this.currentObjects = {}; // name => marker

    this.reDraw = this.reDraw.bind(this);
    this.onMinetestUpdate = this.onMinetestUpdate.bind(this);
  },

  createMarker: function(cart){

    var Icon = L.icon({
      iconUrl: "pics/minecart_logo.png",

      iconSize:     [32, 32],
      iconAnchor:   [16, 16],
      popupAnchor:  [0, -32]
    });

    var marker = L.marker([cart.pos.z, cart.pos.x], {icon: Icon});
    var html = "<b>Minecart</b><hr>";
    html += "<b>Id: </b> " + cart.id + "<br>";

    marker.bindPopup(html);

    return marker;
  },

  isCartInCurrentLayer: function(cart){
    var mapLayer = layerMgr.getCurrentLayer();

    return (cart.pos.y >= (mapLayer.from*16) && cart.pos.y <= (mapLayer.to*16));
  },


  onMinetestUpdate: function(/*info*/){
    var self = this;

    minecarts.forEach(function(cart){
      var isInLayer = self.isCartInCurrentLayer(cart);

      if (!isInLayer){
        if (self.currentObjects[cart.id]){
          //cart is displayed and not on the layer anymore
          //Remove the marker and reference
          self.currentObjects[cart.id].remove();
          delete self.currentObjects[cart.id];
        }

        return;
      }

      if (self.currentObjects[cart.id]){
        //marker exists
        self.currentObjects[cart.id].setLatLng([cart.pos.z, cart.pos.x]);
        //setPopupContent

      } else {
        //marker does not exist
        var marker = self.createMarker(cart);
        marker.addTo(self);

        self.currentObjects[cart.id] = marker;
      }
    });

    Object.keys(self.currentObjects).forEach(function(existingId){
      var cartIsActive = minecarts.find(function(t){
        return t.id == existingId;
      });

      if (!cartIsActive){
        self.currentObjects[existingId].remove();
        delete self.currentObjects[existingId];
      }
    });
  },

  reDraw: function(){
    var self = this;
    this.currentObjects = {};
    this.clearLayers();

    minecarts.forEach(function(cart){
      if (!self.isCartInCurrentLayer(cart)){
        //not in current layer
        return;
      }

      var marker = self.createMarker(cart);
      marker.addTo(self);
      self.currentObjects[cart.id] = marker;
    });

  },

  onAdd: function(/*map*/) {
    wsChannel.addListener("minetest-info", this.onMinetestUpdate);
    this.reDraw();
  },

  onRemove: function(/*map*/) {
    this.clearLayers();
    wsChannel.removeListener("minetest-info", this.onMinetestUpdate);
  }
});