[OpenLayers-Users] Lines disappearing at higer zoom

[Maarten Deen]

Eric Lemoine wrote:
> So you use 2.7, and possibly found a bug in the lib. Could you please
> provide the list with a simple example showing the problem?

Sure.

I have a test page at <http://www.maasluip.nl/ebt/test.html>
It show a series of east-west lines. If you zoom in to a high enough level, the 
lines will disappear, except when you are close enough to the start or end of 
the line. Moving the map closer to the start of the line will make the line 
reappear suddenly.

So I guess it is some sort of "how far is the current point away from the 
starting point, in pixels" bug.
This occurs on Firefox at zoomlevel 13, but IE is not affected by the bug in 
this example.
There is another example at <http://www.maasluip.nl/ebt/ebttest.html> with 
longitudal and lateral lines. Here IE also displays the bug, but at different 
zoomlevels than Firefox.

Code to draw the lines on a map is straightforward:
for (var p=0; p <= 80; p++)
{
   var pointList = [];

   var lonLat0 = new OpenLayers.LonLat(0, p).transform(map.displayProjection, 
map.projection);
   var lonLat1 = new OpenLayers.LonLat(30, p).transform(map.displayProjection, 
map.projection);
   newPoint = new OpenLayers.Geometry.Point(lonLat0.lon, lonLat0.lat);
   pointList.push(newPoint);
   newPoint = new OpenLayers.Geometry.Point(lonLat1.lon, lonLat1.lat);
   pointList.push(newPoint);

   var lineFeature = new OpenLayers.Feature.Vector(
     new OpenLayers.Geometry.LineString(pointList));

   vectorLayer.addFeatures([lineFeature]);
}

This will draw one line each 1 degrees of latitude, in a box from (0,0)-(30,80)

Regards,
Maarten

> 2008/12/7, Maarten Deen <mdeen at xs4all.nl>:
>> I'm using the online one at <http://www.openlayers.org/api/OpenLayers.js>
>>
>> Maarten
>>
>> Eric Lemoine wrote:
>>> Hello
>>>
>>> What version of the lib are you using? A bug looking like what you're
>>> describing was fixed in 2.7.
>>>
>>> Cheers,
>>>
>>> Eric
>>>
>>> 2008/12/7, Maarten Deen <mdeen at xs4all.nl>:
>>>> I have a map on which I draw longitude and latitude lines. The strange
>>>> thing
>>>> is:
>>>> these lines disappear at higer zoom levels.
>>>> In Firefox 3, the longitude disappears from zoom 10 and the latitude from
>>>> zoom
>>>> 11, in IE 6, it is zoom 14 and 13 respectively.
>>>>
>>>> The map is at <http://www.maasluip.nl/ebt/ebttest.html>
>>>>
>>>> Regards,
>>>> Maarten
>>>> _______________________________________________
>>>> Users mailing list
>>>> Users at openlayers.org
>>>> http://openlayers.org/mailman/listinfo/users
>>>>
>>>
>>>
>>
>> _______________________________________________
>> Users mailing list
>> Users at openlayers.org
>> http://openlayers.org/mailman/listinfo/users
>>
>