OpenLayers 2 used to have a getZoomForResolution
method that would give you the zoom level (or closest zoom level) of a given resolution.
I don't see any such method in ol3, for the ol.View
object that is. Is there a way to achieve this with what ol.view
currently have ?
This will give the next closest integer zoom for a give resolution:
function zoomForResolution(resolution) {
var zoom = 0;
var r = 156543.03390625; // resolution for zoom 0
while (resolution < r) {
r /= 2;
zoom++;
if (resolution > r) {
return zoom;
}
}
return zoom; // resolution was greater than 156543.03390625 so return 0
}
zoomForResolution(40); // 12
My brother suggested:
var zoom = Math.ceil( (Math.log(resolution) - Math.log(156543.03390625) ) / Math.log(0.5))
refining the logarithmic solution for browsers with Math.log2()
var zoom = Math.log2(156543.03390625) - Math.log2(resolution);
and for IE which does not have log2()
var zoom = Math.log(156543.03390625) * Math.LOG2E - Math.log(resolution) * Math.LOG2E;