Change zoom precision function

This changes the number of fractional digits to log10(pixels / degrees) with pixels = 2**(8 + zoom) and degrees = 180.

diff --git a/app/assets/javascripts/osm.js.erb b/app/assets/javascripts/osm.js.erb
index e429f4479f143dfe2d50622b870d62d60558a263..e08528f845da2b2cee72780d3197720fbc42ab02 100644 (file)
--- a/app/assets/javascripts/osm.js.erb
+++ b/app/assets/javascripts/osm.js.erb
@@ -204,7 +204,9 @@ OSM = {
   },
 
   zoomPrecision: function(zoom) {
   },
 
   zoomPrecision: function(zoom) {

-    return Math.max(0, Math.ceil(Math.log(zoom) / Math.LN2));
+    var pixels = Math.pow(2, 8 + zoom);
+    var degrees = 180;
+    return Math.ceil(Math.log10(pixels / degrees));

   },
 
   locationCookie: function(map) {
   },
 
   locationCookie: function(map) {