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geo module: add getAverageBearing, getBearingDifference, getClosestBearing (find straightest path, mix two hues, etc.)

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rolux 2013-12-06 21:11:41 +01:00
parent 812e95d740
commit b834bb2b4d
1 changed files with 29 additions and 0 deletions
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29
source/Ox/js/Geo.js
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@ -62,6 +62,21 @@
* Math.abs(pointA.lng - pointB.lng);
};
/*@
Ox.getAverageBearing <f> Returns the average of two bearings
> Ox.getAverageBearing(0, 90)
45
> Ox.getAverageBearing(10, 350)
0
@*/
// FIXME: find the proper name of this operation
// FIMXE: use in manhattan grid example
Ox.getAverageBearing = function(bearingA, bearingB) {
return Ox.mod((bearingA + bearingB) / 2 + (
Math.abs(bearingA - bearingB) > 180 ? 180 : 0
), 360);
};
/*@
Ox.getBearing <f> Returns the bearing from one point to another
> Ox.getBearing({lat: -45, lng: 0}, {lat: 45, lng: 0})
@ -80,6 +95,12 @@
return (Ox.deg(Math.atan2(y, x)) + 360) % 360;
};
// FIXME: name, docs
Ox.getBearingDifference = function(bearingA, bearingB) {
var difference = Math.abs(bearingA - bearingB);
return difference > 180 ? 360 - difference : difference;
};
/*@
Ox.getCenter <f> Returns the center of a recangle on a spehre
> Ox.getCenter({lat: -45, lng: -90}, {lat: 45, lng: 90})
@ -115,6 +136,14 @@
});
};
// FIXME: name, docs
Ox.getClosestBearing = function(bearing, bearings) {
var differences = bearings.map(function(bearing_) {
return getBearingDifference(bearing, bearing_);
});
return bearings[differences.indexOf(Ox.min(differences))];
};
/*@
Ox.getDegreesPerMeter <f> Returns degrees per meter at a given latitude
> 360 / Ox.getDegreesPerMeter(0)