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Fix longitudes outside of [-180,180] range #194

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Fix longitudes outside of [-180,180] range #194

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f4b1838
Fix longitudes outside of [-180,180] range
ka7eh Dec 24, 2021
99c877f
Add test for longitude values outside of -180 and +180 range
ka7eh Dec 24, 2021
9b944aa
Merge branch 'mapbox:main' into main
ka7eh Sep 7, 2022
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2 changes: 1 addition & 1 deletion index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -387,7 +387,7 @@ function getClusterProperties(cluster) {

// longitude/latitude to spherical mercator in [0..1] range
function lngX(lng) {
return lng / 360 + 0.5;
return lng / 360 + 0.5 + (lng > 180 || lng < -180 ? -Math.sign(lng) : 0);
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A slightly simpler / more reliable way to wrap the value:

Suggested change
return lng / 360 + 0.5 + (lng > 180 || lng < -180 ? -Math.sign(lng) : 0);
return ((lng / 360 + 0.5) % 1 + 1) % 1;

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Thanks for the tip on the alternative math. I tested it and unfortunately, it breaks the tests.

With the suggested approach, the returned values from lngX are different from the values from the first solution at their ~14-15 decimal digit, which causes the tests to fail. So I kept the original solution for now.

I've also added a test for this change in 99c877f.

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@mourner just a quick follow-up on this PR to see if there are any other changes you'd like me to include. :)

}
function latY(lat) {
const sin = Math.sin(lat * Math.PI / 180);
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23 changes: 23 additions & 0 deletions test/test.js
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Expand Up @@ -187,3 +187,26 @@ test('makes sure unclustered point coords are not rounded', (t) => {

t.end();
});

test('returns clusters when points are outside of -180 and 180 longitude range', (t) => {
const index = new Supercluster().load([
{
type: 'Feature',
properties: null,
geometry: {
type: 'Point',
coordinates: [-190, 0]
}
}, {
type: 'Feature',
properties: null,
geometry: {
type: 'Point',
coordinates: [190, 0]
}
}
]);

t.equal(index.getClusters([-180, -90, 180, 90], 1).length, 2);
t.end();
});