Document viewport-based limitation on zooming out

[davidtheclark]

I'm told by @samanpwbb that a feature of Mapbox GL JS is that it sets a minimum zoom based on your viewport size, so you can't zoom out far enough to see empty space instead of map. That explains why I've been unable to zoom out to level 0.

I can't find this in the documentation. Is it there? If not, I think it probably should be. I know it confused me.

I tried searching through issues to find a record about this but didn't uncover anything, though I imagine it must have been discussed before and I just didn't find it. Sorry if this is a duplicate.

[asheemmamoowala]

This was fixed in #9028. You can now zoom out to see a full world (i.e z0 tile) even on small viewports and the docs for Map#setMinZoom include:

It is not always possible to zoom out and reach the set minZoom. Other factors such as map height may restrict zooming. For example, if the map is 512px tall it will not be possible to zoom below zoom 0 no matter what the minZoom is set to.