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| goog.provide('ol.geom.flat.geodesic');
goog.require('goog.asserts');
goog.require('goog.object');
goog.require('ol.TransformFunction');
goog.require('ol.math');
goog.require('ol.proj');
/**
* @private
* @param {function(number): ol.Coordinate} interpolate Interpolate function.
* @param {ol.TransformFunction} transform Transform from longitude/latitude to
* projected coordinates.
* @param {number} squaredTolerance Squared tolerance.
* @return {Array.<number>} Flat coordinates.
*/
ol.geom.flat.geodesic.line_ =
function(interpolate, transform, squaredTolerance) {
// FIXME reduce garbage generation
// FIXME optimize stack operations
/** @type {Array.<number>} */
var flatCoordinates = [];
var geoA = interpolate(0);
var geoB = interpolate(1);
var a = transform(geoA);
var b = transform(geoB);
/** @type {Array.<ol.Coordinate>} */
var geoStack = [geoB, geoA];
/** @type {Array.<ol.Coordinate>} */
var stack = [b, a];
/** @type {Array.<number>} */
var fractionStack = [1, 0];
/** @type {Object.<string, boolean>} */
var fractions = {};
var maxIterations = 1e5;
var geoM, m, fracA, fracB, fracM, key;
while (--maxIterations > 0 && fractionStack.length > 0) {
// Pop the a coordinate off the stack
fracA = fractionStack.pop();
geoA = geoStack.pop();
a = stack.pop();
// Add the a coordinate if it has not been added yet
key = fracA.toString();
Eif (!goog.object.containsKey(fractions, key)) {
flatCoordinates.push(a[0], a[1]);
fractions[key] = true;
}
// Pop the b coordinate off the stack
fracB = fractionStack.pop();
geoB = geoStack.pop();
b = stack.pop();
// Find the m point between the a and b coordinates
fracM = (fracA + fracB) / 2;
geoM = interpolate(fracM);
m = transform(geoM);
Eif (ol.math.squaredSegmentDistance(m[0], m[1], a[0], a[1],
b[0], b[1]) < squaredTolerance) {
// If the m point is sufficiently close to the straight line, then we
// discard it. Just use the b coordinate and move on to the next line
// segment.
flatCoordinates.push(b[0], b[1]);
key = fracB.toString();
goog.asserts.assert(!goog.object.containsKey(fractions, key),
'fractions object should contain key : ' + key);
fractions[key] = true;
} else {
// Otherwise, we need to subdivide the current line segment. Split it
// into two and push the two line segments onto the stack.
fractionStack.push(fracB, fracM, fracM, fracA);
stack.push(b, m, m, a);
geoStack.push(geoB, geoM, geoM, geoA);
}
}
goog.asserts.assert(maxIterations > 0,
'maxIterations should be more than 0');
return flatCoordinates;
};
/**
* Generate a great-circle arcs between two lat/lon points.
* @param {number} lon1 Longitude 1 in degrees.
* @param {number} lat1 Latitude 1 in degrees.
* @param {number} lon2 Longitude 2 in degrees.
* @param {number} lat2 Latitude 2 in degrees.
* @param {ol.proj.Projection} projection Projection.
* @param {number} squaredTolerance Squared tolerance.
* @return {Array.<number>} Flat coordinates.
*/
ol.geom.flat.geodesic.greatCircleArc = function(
lon1, lat1, lon2, lat2, projection, squaredTolerance) {
var geoProjection = ol.proj.get('EPSG:4326');
var cosLat1 = Math.cos(ol.math.toRadians(lat1));
var sinLat1 = Math.sin(ol.math.toRadians(lat1));
var cosLat2 = Math.cos(ol.math.toRadians(lat2));
var sinLat2 = Math.sin(ol.math.toRadians(lat2));
var cosDeltaLon = Math.cos(ol.math.toRadians(lon2 - lon1));
var sinDeltaLon = Math.sin(ol.math.toRadians(lon2 - lon1));
var d = sinLat1 * sinLat2 + cosLat1 * cosLat2 * cosDeltaLon;
return ol.geom.flat.geodesic.line_(
/**
* @param {number} frac Fraction.
* @return {ol.Coordinate} Coordinate.
*/
function(frac) {
if (1 <= d) {
return [lon2, lat2];
}
var D = frac * Math.acos(d);
var cosD = Math.cos(D);
var sinD = Math.sin(D);
var y = sinDeltaLon * cosLat2;
var x = cosLat1 * sinLat2 - sinLat1 * cosLat2 * cosDeltaLon;
var theta = Math.atan2(y, x);
var lat = Math.asin(sinLat1 * cosD + cosLat1 * sinD * Math.cos(theta));
var lon = ol.math.toRadians(lon1) +
Math.atan2(Math.sin(theta) * sinD * cosLat1,
cosD - sinLat1 * Math.sin(lat));
return [ol.math.toDegrees(lon), ol.math.toDegrees(lat)];
}, ol.proj.getTransform(geoProjection, projection), squaredTolerance);
};
/**
* Generate a meridian (line at constant longitude).
* @param {number} lon Longitude.
* @param {number} lat1 Latitude 1.
* @param {number} lat2 Latitude 2.
* @param {ol.proj.Projection} projection Projection.
* @param {number} squaredTolerance Squared tolerance.
* @return {Array.<number>} Flat coordinates.
*/
ol.geom.flat.geodesic.meridian =
function(lon, lat1, lat2, projection, squaredTolerance) {
var epsg4326Projection = ol.proj.get('EPSG:4326');
return ol.geom.flat.geodesic.line_(
/**
* @param {number} frac Fraction.
* @return {ol.Coordinate} Coordinate.
*/
function(frac) {
return [lon, lat1 + ((lat2 - lat1) * frac)];
},
ol.proj.getTransform(epsg4326Projection, projection), squaredTolerance);
};
/**
* Generate a parallel (line at constant latitude).
* @param {number} lat Latitude.
* @param {number} lon1 Longitude 1.
* @param {number} lon2 Longitude 2.
* @param {ol.proj.Projection} projection Projection.
* @param {number} squaredTolerance Squared tolerance.
* @return {Array.<number>} Flat coordinates.
*/
ol.geom.flat.geodesic.parallel =
function(lat, lon1, lon2, projection, squaredTolerance) {
var epsg4326Projection = ol.proj.get('EPSG:4326');
return ol.geom.flat.geodesic.line_(
/**
* @param {number} frac Fraction.
* @return {ol.Coordinate} Coordinate.
*/
function(frac) {
return [lon1 + ((lon2 - lon1) * frac), lat];
},
ol.proj.getTransform(epsg4326Projection, projection), squaredTolerance);
};
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