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May 11, 2018 06:58
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Browserifiied version of arc.js
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(function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.arc = f()}})(function(){var define,module,exports;return (function(){function r(e,n,t){function o(i,f){if(!n[i]){if(!e[i]){var c="function"==typeof require&&require;if(!f&&c)return c(i,!0);if(u)return u(i,!0);var a=new Error("Cannot find module '"+i+"'");throw a.code="MODULE_NOT_FOUND",a}var p=n[i]={exports:{}};e[i][0].call(p.exports,function(r){var n=e[i][1][r];return o(n||r)},p,p.exports,r,e,n,t)}return n[i].exports}for(var u="function"==typeof require&&require,i=0;i<t.length;i++)o(t[i]);return o}return r})()({1:[function(require,module,exports){ | |
'use strict'; | |
var D2R = Math.PI / 180; | |
var R2D = 180 / Math.PI; | |
var Coord = function(lon,lat) { | |
this.lon = lon; | |
this.lat = lat; | |
this.x = D2R * lon; | |
this.y = D2R * lat; | |
}; | |
Coord.prototype.view = function() { | |
return String(this.lon).slice(0, 4) + ',' + String(this.lat).slice(0, 4); | |
}; | |
Coord.prototype.antipode = function() { | |
var anti_lat = -1 * this.lat; | |
var anti_lon = (this.lon < 0) ? 180 + this.lon : (180 - this.lon) * -1; | |
return new Coord(anti_lon, anti_lat); | |
}; | |
var LineString = function() { | |
this.coords = []; | |
this.length = 0; | |
}; | |
LineString.prototype.move_to = function(coord) { | |
this.length++; | |
this.coords.push(coord); | |
}; | |
var Arc = function(properties) { | |
this.properties = properties || {}; | |
this.geometries = []; | |
}; | |
Arc.prototype.json = function() { | |
if (this.geometries.length <= 0) { | |
return {'geometry': { 'type': 'LineString', 'coordinates': null }, | |
'type': 'Feature', 'properties': this.properties | |
}; | |
} else if (this.geometries.length == 1) { | |
return {'geometry': { 'type': 'LineString', 'coordinates': this.geometries[0].coords }, | |
'type': 'Feature', 'properties': this.properties | |
}; | |
} else { | |
var multiline = []; | |
for (var i = 0; i < this.geometries.length; i++) { | |
multiline.push(this.geometries[i].coords); | |
} | |
return {'geometry': { 'type': 'MultiLineString', 'coordinates': multiline }, | |
'type': 'Feature', 'properties': this.properties | |
}; | |
} | |
}; | |
// TODO - output proper multilinestring | |
Arc.prototype.wkt = function() { | |
var wkt_string = ''; | |
var wkt = 'LINESTRING('; | |
var collect = function(c) { wkt += c[0] + ' ' + c[1] + ','; }; | |
for (var i = 0; i < this.geometries.length; i++) { | |
if (this.geometries[i].coords.length === 0) { | |
return 'LINESTRING(empty)'; | |
} else { | |
var coords = this.geometries[i].coords; | |
coords.forEach(collect); | |
wkt_string += wkt.substring(0, wkt.length - 1) + ')'; | |
} | |
} | |
return wkt_string; | |
}; | |
/* | |
* http://en.wikipedia.org/wiki/Great-circle_distance | |
* | |
*/ | |
var GreatCircle = function(start,end,properties) { | |
if (!start || start.x === undefined || start.y === undefined) { | |
throw new Error("GreatCircle constructor expects two args: start and end objects with x and y properties"); | |
} | |
if (!end || end.x === undefined || end.y === undefined) { | |
throw new Error("GreatCircle constructor expects two args: start and end objects with x and y properties"); | |
} | |
this.start = new Coord(start.x,start.y); | |
this.end = new Coord(end.x,end.y); | |
this.properties = properties || {}; | |
var w = this.start.x - this.end.x; | |
var h = this.start.y - this.end.y; | |
var z = Math.pow(Math.sin(h / 2.0), 2) + | |
Math.cos(this.start.y) * | |
Math.cos(this.end.y) * | |
Math.pow(Math.sin(w / 2.0), 2); | |
this.g = 2.0 * Math.asin(Math.sqrt(z)); | |
if (this.g == Math.PI) { | |
throw new Error('it appears ' + start.view() + ' and ' + end.view() + " are 'antipodal', e.g diametrically opposite, thus there is no single route but rather infinite"); | |
} else if (isNaN(this.g)) { | |
throw new Error('could not calculate great circle between ' + start + ' and ' + end); | |
} | |
}; | |
/* | |
* http://williams.best.vwh.net/avform.htm#Intermediate | |
*/ | |
GreatCircle.prototype.interpolate = function(f) { | |
var A = Math.sin((1 - f) * this.g) / Math.sin(this.g); | |
var B = Math.sin(f * this.g) / Math.sin(this.g); | |
var x = A * Math.cos(this.start.y) * Math.cos(this.start.x) + B * Math.cos(this.end.y) * Math.cos(this.end.x); | |
var y = A * Math.cos(this.start.y) * Math.sin(this.start.x) + B * Math.cos(this.end.y) * Math.sin(this.end.x); | |
var z = A * Math.sin(this.start.y) + B * Math.sin(this.end.y); | |
var lat = R2D * Math.atan2(z, Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2))); | |
var lon = R2D * Math.atan2(y, x); | |
return [lon, lat]; | |
}; | |
/* | |
* Generate points along the great circle | |
*/ | |
GreatCircle.prototype.Arc = function(npoints,options) { | |
var first_pass = []; | |
if (!npoints || npoints <= 2) { | |
first_pass.push([this.start.lon, this.start.lat]); | |
first_pass.push([this.end.lon, this.end.lat]); | |
} else { | |
var delta = 1.0 / (npoints - 1); | |
for (var i = 0; i < npoints; ++i) { | |
var step = delta * i; | |
var pair = this.interpolate(step); | |
first_pass.push(pair); | |
} | |
} | |
/* partial port of dateline handling from: | |
gdal/ogr/ogrgeometryfactory.cpp | |
TODO - does not handle all wrapping scenarios yet | |
*/ | |
var bHasBigDiff = false; | |
var dfMaxSmallDiffLong = 0; | |
// from http://www.gdal.org/ogr2ogr.html | |
// -datelineoffset: | |
// (starting with GDAL 1.10) offset from dateline in degrees (default long. = +/- 10deg, geometries within 170deg to -170deg will be splited) | |
var dfDateLineOffset = options && options.offset ? options.offset : 10; | |
var dfLeftBorderX = 180 - dfDateLineOffset; | |
var dfRightBorderX = -180 + dfDateLineOffset; | |
var dfDiffSpace = 360 - dfDateLineOffset; | |
// https://github.com/OSGeo/gdal/blob/7bfb9c452a59aac958bff0c8386b891edf8154ca/gdal/ogr/ogrgeometryfactory.cpp#L2342 | |
for (var j = 1; j < first_pass.length; ++j) { | |
var dfPrevX = first_pass[j-1][0]; | |
var dfX = first_pass[j][0]; | |
var dfDiffLong = Math.abs(dfX - dfPrevX); | |
if (dfDiffLong > dfDiffSpace && | |
((dfX > dfLeftBorderX && dfPrevX < dfRightBorderX) || (dfPrevX > dfLeftBorderX && dfX < dfRightBorderX))) { | |
bHasBigDiff = true; | |
} else if (dfDiffLong > dfMaxSmallDiffLong) { | |
dfMaxSmallDiffLong = dfDiffLong; | |
} | |
} | |
var poMulti = []; | |
if (bHasBigDiff && dfMaxSmallDiffLong < dfDateLineOffset) { | |
var poNewLS = []; | |
poMulti.push(poNewLS); | |
for (var k = 0; k < first_pass.length; ++k) { | |
var dfX0 = parseFloat(first_pass[k][0]); | |
if (k > 0 && Math.abs(dfX0 - first_pass[k-1][0]) > dfDiffSpace) { | |
var dfX1 = parseFloat(first_pass[k-1][0]); | |
var dfY1 = parseFloat(first_pass[k-1][1]); | |
var dfX2 = parseFloat(first_pass[k][0]); | |
var dfY2 = parseFloat(first_pass[k][1]); | |
if (dfX1 > -180 && dfX1 < dfRightBorderX && dfX2 == 180 && | |
k+1 < first_pass.length && | |
first_pass[k-1][0] > -180 && first_pass[k-1][0] < dfRightBorderX) | |
{ | |
poNewLS.push([-180, first_pass[k][1]]); | |
k++; | |
poNewLS.push([first_pass[k][0], first_pass[k][1]]); | |
continue; | |
} else if (dfX1 > dfLeftBorderX && dfX1 < 180 && dfX2 == -180 && | |
k+1 < first_pass.length && | |
first_pass[k-1][0] > dfLeftBorderX && first_pass[k-1][0] < 180) | |
{ | |
poNewLS.push([180, first_pass[k][1]]); | |
k++; | |
poNewLS.push([first_pass[k][0], first_pass[k][1]]); | |
continue; | |
} | |
if (dfX1 < dfRightBorderX && dfX2 > dfLeftBorderX) | |
{ | |
// swap dfX1, dfX2 | |
var tmpX = dfX1; | |
dfX1 = dfX2; | |
dfX2 = tmpX; | |
// swap dfY1, dfY2 | |
var tmpY = dfY1; | |
dfY1 = dfY2; | |
dfY2 = tmpY; | |
} | |
if (dfX1 > dfLeftBorderX && dfX2 < dfRightBorderX) { | |
dfX2 += 360; | |
} | |
if (dfX1 <= 180 && dfX2 >= 180 && dfX1 < dfX2) | |
{ | |
var dfRatio = (180 - dfX1) / (dfX2 - dfX1); | |
var dfY = dfRatio * dfY2 + (1 - dfRatio) * dfY1; | |
poNewLS.push([first_pass[k-1][0] > dfLeftBorderX ? 180 : -180, dfY]); | |
poNewLS = []; | |
poNewLS.push([first_pass[k-1][0] > dfLeftBorderX ? -180 : 180, dfY]); | |
poMulti.push(poNewLS); | |
} | |
else | |
{ | |
poNewLS = []; | |
poMulti.push(poNewLS); | |
} | |
poNewLS.push([dfX0, first_pass[k][1]]); | |
} else { | |
poNewLS.push([first_pass[k][0], first_pass[k][1]]); | |
} | |
} | |
} else { | |
// add normally | |
var poNewLS0 = []; | |
poMulti.push(poNewLS0); | |
for (var l = 0; l < first_pass.length; ++l) { | |
poNewLS0.push([first_pass[l][0],first_pass[l][1]]); | |
} | |
} | |
var arc = new Arc(this.properties); | |
for (var m = 0; m < poMulti.length; ++m) { | |
var line = new LineString(); | |
arc.geometries.push(line); | |
var points = poMulti[m]; | |
for (var j0 = 0; j0 < points.length; ++j0) { | |
line.move_to(points[j0]); | |
} | |
} | |
return arc; | |
}; | |
if (typeof module !== 'undefined' && typeof module.exports !== 'undefined') { | |
// nodejs | |
module.exports.Coord = Coord; | |
module.exports.Arc = Arc; | |
module.exports.GreatCircle = GreatCircle; | |
} else { | |
// browser | |
var arc = {}; | |
arc.Coord = Coord; | |
arc.Arc = Arc; | |
arc.GreatCircle = GreatCircle; | |
} | |
},{}]},{},[1])(1) | |
}); |
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