show/hide kml on defined zoom levels - zooming

Question

I´m trying to hide/show my own kml files (polygons) depending on zoom levels in OpenLayers - when reached certain zoom level one layer should hide and another show. So far I found this solution (How to load layers depending on zoom level?), but it doesn´t seem to be working in my case. I´m relatively new to javascript and I don´t know if I´m using this right, I also made some changes to the example:
map.events.register("zoomend", map, zoomChanged); //inserted in function init()
function zoomChanged()
{
if (map.getZoom() == 18)
{
kml1.setVisibility (true);
kml2.setVisibility (false);
}
else if (map.getZoom() == 19)
{
kml1.setVisibility (false);
kml2.setVisibility (true);
}
}
I also tried another solution to hide kml1, but in this case my layer isn´t drawn. The LayerSwitcher works - the layer is unselectable in defined zoom levels, but nothing is visible when zoomed out (when layer is already selectable):
var kml1 = new OpenLayers.Layer.Vector("prehled",
{minScale: 1000,}, //1:1000
{
projection: map.displayProjection,
strategies: [new OpenLayers.Strategy.Fixed()],
protocol: new OpenLayers.Protocol.HTTP({
url: "kml/zahrada.kml",
format: new OpenLayers.Format.KML({
extractStyles: true,
extractAttributes: true,
})
})
});
map.addLayer(kml1);
Thanks for any response and advice on this.

Answer 1

Try:
var kml1 = new OpenLayers.Layer.Vector("prehled", {
minResolution: map.getResolutionForZoom(18), // or the desired maximum zoom
projection: map.displayProjection,
strategies: [new OpenLayers.Strategy.Fixed()],
protocol: new OpenLayers.Protocol.HTTP({
url: "kml/zahrada.kml",
format: new OpenLayers.Format.KML({
extractStyles: true,
extractAttributes: true
})
})
});
map.addLayer(kml1);
```