[OpenLayers-Users] WMS overlay disappearing with Google Maps v.3

[Dalton Filho]

Hello Gery,

Thank you for your help. I'm using version 2.12. I removed the redundant
setBaseLayer(gsat)line but the WMS overlay still fails to appear unless I
zoom out twice. I did the same test using version 2.11 but results are
identical. After I zoom in to a certain zoom level the overlay simply
disappears whereas in the Google Maps v.2 test they did show at that same
zoom level.

I compared the stack trace of zoom-in requests that rendered the overlay
with the stack trace of requests that did not render it. The point where it
fails is the method
Tile.shouldDraw()<https://github.com/openlayers/openlayers/blob/master/lib/OpenLayers/Tile.js>.
It is returning false for the zoom-in requests for which the overlay was
not rendered. This method returns true when the overlays are rendered. This
is the method in question:

    shouldDraw: function() {
        var withinMaxExtent = false,
            maxExtent = this.layer.maxExtent;

        if (maxExtent) {
            var map = this.layer.map;
            var worldBounds = map.baseLayer.wrapDateLine && map.getMaxExtent();
            if (this.bounds.intersectsBounds(maxExtent, {inclusive:
false, worldBounds: worldBounds})) {
                withinMaxExtent = true;
            }
        }

        return withinMaxExtent || this.layer.displayOutsideMaxExtent;
    },


I captured the value of the worldBounds, this.bounds and maxExtent
variables inside it to create a test that anyone can reproduce:


// Test #1: values captured in a zoom request for which the WMS overlay was
NOT rendered
function test1() {
    var bounds = new OpenLayers.Bounds(-3785006.7128486, 2429373.3721214,
3729058.9146514, 8064922.5927464);
    var maxExtent = new OpenLayers.Bounds(-180, -90, 180, 90);
    var worldBounds = new OpenLayers.Bounds(-20037508.34, -20037508.34,
20037508.34, 20037508.34);

    if (bounds.intersectsBounds(maxExtent, {inclusive: false, worldBounds:
worldBounds})) {
        return "Intersected";
    }

    return "Not intersected";
}

//Example #2: values captured in a zoom request for which the WMS overlay
did render
function test2() {
    var bounds = new OpenLayers.Bounds(-7776854.077458, -677027.4569557,
7251277.177542, 10594070.984294);
    var maxExtent = new OpenLayers.Bounds(-180, -90, 180, 90);
    var worldBounds = new OpenLayers.Bounds(-20037508.34, -20037508.34,
20037508.34, 20037508.34);

    if (bounds.intersectsBounds(maxExtent, {inclusive: false, worldBounds:
worldBounds})) {
        return "Intersected";
    }

    return "Not intersected";
}


Does anyone in the community knows why the first test does not intersect?

- Is the Bounds.intersectsBounds() implementation incorrect?
- Are any of these values inside the function invalid or absurd? If so, why?

In the meanwhile the only thing I can do is to skip the shouldDraw()
verification and force draw = true inside Tile.draw(). A dirty hack to keep
me afloat...


Best regards,

Dalton

On Sat, Apr 20, 2013 at 1:32 PM, Gery . <gamejihou at hotmail.com> wrote:

> Hi Dalton,
>
> Are you using OL 2.12 or 2.11? I don't think you need
> setBaseLayer(gsat);
> because you already set that. I use google3 and 2.11 and it works perfect
> without that.
>
> HTH,
>
> Cheers,
>
> Gery
>
>
> Sent from my iBath
>
> On Apr 20, 2013, at 17:56, "Dalton Filho" <daltonfilho at gmail.com> wrote:
>
> Hello list,
>
> I created a map with Google layers as base layers + a WMS overlay layer.
> Unfortunately the WMS overlay disappears when zooming in. In fact, you can
> only start seeing the WMS overlay after you zoom out twice.
>
> In another test I created a map with Google Maps v.2 base layers + the
> *same* WMS overlay layer I used in the first test. This time the WMS
> overlay shows in all zoom levels.
>
> I have attached 4 files that reproduce the error (you should edit the
> openlayers inclusion or paste them under the examples directory)
>
> Has anyone had the same issue?
>
> Best regards,
>
> Dalton
> <google-v2-test.html>
> <google-v2-test.js>
> <google-v3-test.html>
> <google-v3-test.js>
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