restore the code that prevents rendering short links. seems like the backend isn't removing enough (any?) links again, so they were having a big impact on performance

code/map_data_render.js

@@ -10,6 +10,9 @@ window.Render = function() {
   this.CLUSTER_SIZE = L.Browser.mobile ? 16 : 8;  // the map is divided into squares of this size in pixels for clustering purposes. mobile uses larger markers, so therefore larger clustering areas
   this.CLUSTER_PORTAL_LIMIT = 4; // no more than this many portals are drawn in each cluster square
 
+  // link length, in pixels, to be visible. use the portal cluster size, as shorter than this is likely hidden
+  // under the portals
+  this.LINK_VISIBLE_PIXEL_LENGTH = this.CLUSTER_SIZE;
 
   this.entityVisibilityZoom = undefined;
 
@@ -395,8 +398,11 @@ window.Render.prototype.createLinkEntity = function(ent,faked) {
 
   window.links[ent[0]] = poly;
 
+  // only add the link to the layer if it's long enough to be seen
+  if (this.linkVisible(poly)) {
     linksFactionLayers[poly.options.team].addLayer(poly);
   }
+}
 
 
 
@@ -405,6 +411,7 @@ window.Render.prototype.updateEntityVisibility = function() {
     this.entityVisibilityZoom = map.getZoom();
 
     this.resetPortalClusters();
+    this.resetLinkVisibility();
 
     if (this.portalMarkerScale === undefined || this.portalMarkerScale != portalMarkerScale()) {
       this.portalMarkerScale = portalMarkerScale();
@@ -511,3 +518,46 @@ window.Render.prototype.getPortalClusterID = function(portal) {
 }
 
 
+
+window.Render.prototype.linkVisible = function(link) {
+  var lengthSquared = this.getLinkPixelLengthSquared (link);
+
+  return lengthSquared >= this.LINK_VISIBLE_PIXEL_LENGTH*this.LINK_VISIBLE_PIXEL_LENGTH;
+}
+
+
+window.Render.prototype.resetLinkVisibility = function() {
+
+  for (var guid in window.links) {
+    var link = window.links[guid];
+
+    var visible = this.linkVisible(link);
+
+    if (visible) {
+      if (!linksFactionLayers[link.options.team].hasLayer(link)) linksFactionLayers[link.options.team].addLayer(link);
+    } else {
+      if (linksFactionLayers[link.options.team].hasLayer(link)) linksFactionLayers[link.options.team].removeLayer(link);
+    }
+  }
+}
+
+
+window.Render.prototype.getLinkPixelLengthSquared = function(link) {
+  var z = map.getZoom();
+
+  var latLngs = link.getLatLngs();
+  if (latLngs.length != 2) {
+    console.warn ('Link had '+latLngs.length+' points - expected 2!');
+    return undefined;
+  }
+
+  var point0 = map.project(latLngs[0]);
+  var point1 = map.project(latLngs[1]);
+
+  var dx = point0.x - point1.x;
+  var dy = point0.y - point1.y;
+
+  var lengthSquared = (dx*dx)+(dy*dy);
+
+  return lengthSquared;
+}