Changing opacity of map outside feature in OpenLayers 3?

Question

I want to change opacity of map outside feature (which is closed polygon) in OpenLayers 3.

Is it possible?

Answer 1

Yes, it is. You can use a plugin for this purpose from https://github.com/Viglino/ol3-ext You can see an example in action at http://viglino.github.io/ol3-ext/examples/map.filter.crop.html