add Ox.containsArea (true if an area contains another one), Ox.intersectAreas (the area/s contained in all areas) and Ox.joinAreas (the smallest area contaning all areas)
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rolux
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@ -17,6 +17,13 @@
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});
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}
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function splitArea(area) {
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return Ox.crossesDateline(area.sw, area.ne) ? [
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{sw: area.sw, ne: {lat: area.ne.lat, lng: 180}},
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{sw: {lat: area.sw.lat, lng: -180}, ne: area.ne}
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] : [area];
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}
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/*@
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Ox.crossesDateline <f> Returns true if a given line crosses the dateline
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> Ox.crossesDateline({lat: 0, lng: -90}, {lat: 0, lng: 90})
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@ -24,6 +31,7 @@
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> Ox.crossesDateline({lat: 0, lng: 90}, {lat: 0, lng: -90})
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true
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@*/
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// FIXME: argument should be {w: ..., e: ...}
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Ox.crossesDateline = function(pointA, pointB) {
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return pointA.lng > pointB.lng;
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};
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@ -31,6 +39,7 @@
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/*@
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Ox.getArea <f> Returns the area in square meters of a given rectancle
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@*/
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// FIXME: argument should be {sw: ..., ne: ...}
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Ox.getArea = function(pointA, pointB) {
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/*
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area of a ring between two latitudes:
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@ -222,6 +231,221 @@
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return point.lat < Ox.MIN_LATITUDE || point.lat > Ox.MAX_LATITUDE;
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};
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/*@
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Ox.containsArea <f> Returns true if an area contains another area
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<script>
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Ox.test.areas = [
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{sw: {lat: -30, lng: -30}, ne: {lat: 30, lng: 30}},
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{sw: {lat: -20, lng: -40}, ne: {lat: 20, lng: 40}},
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{sw: {lat: -30, lng: 150}, ne: {lat: 30, lng: -150}},
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{sw: {lat: 10, lng: -170}, ne: {lat: 20, lng: -160}}
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];
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</script>
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> Ox.containsArea(Ox.test.areas[0], Ox.test.areas[1])
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false
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> Ox.containsArea(Ox.test.areas[2], Ox.test.areas[3])
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true
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@*/
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Ox.containsArea = function(areaA, areaB) {
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// If an area crosses the dateline,
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// we split it into two parts,
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// west and east of the dateline
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var areas = [areaA, areaB].map(splitArea),
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ret;
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function contains(areaA, areaB) {
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return areaA.sw.lat <= areaB.sw.lat
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&& areaA.sw.lng <= areaB.sw.lng
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&& areaA.ne.lat >= areaB.ne.lat
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&& areaA.ne.lng >= areaB.ne.lng;
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}
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// For each part of the inner area, test if it
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// is contained in any part of the outer area
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Ox.forEach(areas[1], function(area1) {
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Ox.forEach(areas[0], function(area0) {
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ret = contains(area0, area1);
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// Break if the outer part contains the inner part
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return !ret;
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});
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// Break if no outer part contains the inner part
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return ret;
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});
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return ret;
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};
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/*@
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Ox.intersectAreas <f> Returns the intersection of two areas, or null
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<script>
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Ox.test.areas = [
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{sw: {lat: -10, lng: -10}, ne: {lat: 0, lng: 0}},
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{sw: {lat: 0, lng: 0}, ne: {lat: 10, lng: 10}},
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{sw: {lat: -30, lng: 150}, ne: {lat: 30, lng: -150}},
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{sw: {lat: 25, lng: -155}, ne: {lat: 35, lng: -145}}
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];
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</script>
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> Ox.intersectAreas([Ox.test.areas[0], Ox.test.areas[1]])
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{sw: {lat: 0, lng: 0}, ne: {lat: 0, lng: 0}}
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> Ox.intersectAreas([Ox.test.areas[2], Ox.test.areas[3]])
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{sw: {lat: 25, lng: -155}, ne: {lat: 30, lng: -150}}
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@*/
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Ox.intersectAreas = function(areas) {
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// FIXME: handle the a corner case where
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// two areas have two intersections
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var intersections, ret;
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// If an area crosses the dateline,
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// we split it into two parts,
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// west and east of the dateline
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areas = areas.map(splitArea);
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ret = areas[0];
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function intersect(areaA, areaB) {
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return areaA.sw.lat > areaB.ne.lat
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|| areaA.sw.lng > areaB.ne.lng
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|| areaA.ne.lat < areaB.sw.lat
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|| areaA.ne.lng < areaB.sw.lng
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? null : {
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sw: {
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lat: Math.max(areaA.sw.lat, areaB.sw.lat),
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lng: Math.max(areaA.sw.lng, areaB.sw.lng)
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},
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ne: {
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lat: Math.min(areaA.ne.lat, areaB.ne.lat),
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lng: Math.min(areaA.ne.lng, areaB.ne.lng)
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}
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};
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}
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Ox.forEach(Ox.sub(areas, 1), function(parts) {
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if (ret.length == 1 && parts.length == 1) {
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ret = intersect(ret[0], parts[0]);
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} else {
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// intersect each part of the intersection
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// with all parts of the next area
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intersections = Ox.compact(ret.map(function(part) {
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return Ox.intersectAreas(Ox.merge(part, parts));
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}));
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ret = intersections.length == 0 ? null
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: Ox.joinAreas(intersections);
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}
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if (ret === null) {
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return false;
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} else {
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ret = splitArea(ret);
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}
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});
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return ret ? Ox.joinAreas(ret) : null;
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};
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/*@
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Ox.joinAreas <f> Joins an array of areas
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<script>
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Ox.test.areas = [
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{sw: {lat: -30, lng: 150}, ne: {lat: -20, lng: 160}},
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{sw: {lat: -10, lng: 170}, ne: {lat: 10, lng: -170}},
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{sw: {lat: 20, lng: -160}, ne: {lat: 30, lng: -150}}
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];
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</script>
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> Ox.joinAreas(Ox.test.areas)
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{sw: {lat: -30, lng: 150}, ne: {lat: 30, lng: -150}}
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@*/
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Ox.joinAreas = function(areas) {
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// While the combined latitude is trivial (min to max), the combined longitude
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// spans from the eastern to the western edge of the largest gap between areas
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var ret = areas[0],
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gaps = [{
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sw: {lat: -90, lng: ret.ne.lng},
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ne: {lat: 90, lng: ret.sw.lng}
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}];
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function containsGaps(area) {
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return Ox.map(gaps, function(gap, i) {
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return Ox.containsArea({
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sw: {lat: -90, lng: area.sw.lng},
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ne: {lat: 90, lng: area.ne.lng}
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}, gap) ? i : null;
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});
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}
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function intersectsWithGaps(area) {
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var ret = {};
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gaps.forEach(function(gap, i) {
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var intersection = Ox.intersectAreas([area, gap]);
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if (intersection) {
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ret[i] = intersection;
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}
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});
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return ret;
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}
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function isContainedInGap(area) {
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var ret = -1;
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Ox.forEach(gaps, function(gap, i) {
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if (Ox.containsArea(gap, area)) {
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ret = i;
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return false;
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}
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});
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return ret;
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}
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Ox.sub(areas, 1).forEach(function(area) {
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var index, indices, intersections;
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if (area.sw.lat < ret.sw.lat) {
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ret.sw.lat = area.sw.lat;
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}
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if (area.ne.lat > ret.ne.lat) {
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ret.ne.lat = area.ne.lat;
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}
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// If the area is contained in a gap, split the gap in two
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index = isContainedInGap(area);
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if (index > -1) {
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gaps.push({
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sw: gaps[index].sw,
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ne: {lat: 90, lng: area.sw.lng}
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});
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gaps.push({
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sw: {lat: -90, lng: area.ne.lng},
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ne: gaps[index].ne
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});
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gaps.splice(index, 1);
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} else {
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// If the area contains gaps, remove them
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indices = containsGaps(area);
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Ox.reverse(indices).forEach(function(index) {
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gaps.splice(index, 1);
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});
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// If the area intersects with gaps, shrink them
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intersections = intersectsWithGaps(area);
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Ox.forEach(intersections, function(intersection, index) {
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gaps[index] = {
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sw: {
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lat: -90,
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lng: gaps[index].sw.lng == intersection.sw.lng
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? intersection.ne.lng : gaps[index].sw.lng
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},
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ne: {
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lat: 90,
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lng: gaps[index].ne.lng == intersection.ne.lng
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? intersection.sw.lng : gaps[index].ne.lng
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}
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};
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});
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}
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});
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if (gaps.length == 0) {
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ret.sw.lng = -180;
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ret.ne.lng = 180;
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} else {
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gaps.sort(function(a, b) {
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return (
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b.ne.lng
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+ (Ox.crossesDateline(b.sw, b.ne) ? 360 : 0)
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- b.sw.lng
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) - (
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a.ne.lng
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+ (Ox.crossesDateline(a.sw, a.ne) ? 360 : 0)
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- a.sw.lng
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);
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});
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ret.sw.lng = gaps[0].ne.lng;
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ret.ne.lng = gaps[0].sw.lng;
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}
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return ret;
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};
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}());
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//@ Ox.Line <f> (undocumented)
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