From c69974f4606f2093c5d7902258fbda141768a684 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=C3=89ric=20Lemoine?= Date: Thu, 9 Oct 2014 13:20:51 +0200 Subject: [PATCH] Add more explanations to xyz-esri-4326-512 example --- examples/xyz-esri-4326-512.js | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/examples/xyz-esri-4326-512.js b/examples/xyz-esri-4326-512.js index 7f525ff5c1..64f865633f 100644 --- a/examples/xyz-esri-4326-512.js +++ b/examples/xyz-esri-4326-512.js @@ -14,10 +14,18 @@ var attribution = new ol.Attribution({ var projection = ol.proj.get('EPSG:4326'); var projectionExtent = projection.getExtent(); -var size = ol.extent.getWidth(projectionExtent) / 256; +// The tile size supported by the ArcGIS tile service. +var tileSize = 512; + +// Calculate the resolutions supported by the ArcGIS tile service. +// There are 16 resolutions, with a factor of 2 between successive +// resolutions. The max resolution is such that the world (360°) +// fits into two (512x512 px) tiles. +var maxResolution = ol.extent.getWidth(projectionExtent) / (tileSize * 2); var resolutions = new Array(16); -for (var z = 2; z < 18; ++z) { - resolutions[z - 2] = size / Math.pow(2, z); +var z; +for (z = 0; z < 16; ++z) { + resolutions[z] = maxResolution / Math.pow(2, z); } var url = 'http://services.arcgisonline.com/arcgis/rest/services/' +