Files
iD/modules/geo/geo.js
2016-12-21 11:21:06 -05:00

277 lines
7.7 KiB
JavaScript

import _ from 'lodash';
export function geoRoundCoords(c) {
return [Math.floor(c[0]), Math.floor(c[1])];
}
export function geoInterp(p1, p2, t) {
return [p1[0] + (p2[0] - p1[0]) * t,
p1[1] + (p2[1] - p1[1]) * t];
}
// 2D cross product of OA and OB vectors, i.e. z-component of their 3D cross product.
// Returns a positive value, if OAB makes a counter-clockwise turn,
// negative for clockwise turn, and zero if the points are collinear.
export function geoCross(o, a, b) {
return (a[0] - o[0]) * (b[1] - o[1]) - (a[1] - o[1]) * (b[0] - o[0]);
}
// http://jsperf.com/id-dist-optimization
export function geoEuclideanDistance(a, b) {
var x = a[0] - b[0], y = a[1] - b[1];
return Math.sqrt((x * x) + (y * y));
}
// using WGS84 polar radius (6356752.314245179 m)
// const = 2 * PI * r / 360
export function geoLatToMeters(dLat) {
return dLat * 110946.257617;
}
// using WGS84 equatorial radius (6378137.0 m)
// const = 2 * PI * r / 360
export function geoLonToMeters(dLon, atLat) {
return Math.abs(atLat) >= 90 ? 0 :
dLon * 111319.490793 * Math.abs(Math.cos(atLat * (Math.PI/180)));
}
// using WGS84 polar radius (6356752.314245179 m)
// const = 2 * PI * r / 360
export function geoMetersToLat(m) {
return m / 110946.257617;
}
// using WGS84 equatorial radius (6378137.0 m)
// const = 2 * PI * r / 360
export function geoMetersToLon(m, atLat) {
return Math.abs(atLat) >= 90 ? 0 :
m / 111319.490793 / Math.abs(Math.cos(atLat * (Math.PI/180)));
}
export function geoOffsetToMeters(offset) {
var equatRadius = 6356752.314245179,
polarRadius = 6378137.0,
tileSize = 256;
return [
offset[0] * 2 * Math.PI * equatRadius / tileSize,
-offset[1] * 2 * Math.PI * polarRadius / tileSize
];
}
export function geoMetersToOffset(meters) {
var equatRadius = 6356752.314245179,
polarRadius = 6378137.0,
tileSize = 256;
return [
meters[0] * tileSize / (2 * Math.PI * equatRadius),
-meters[1] * tileSize / (2 * Math.PI * polarRadius)
];
}
// Equirectangular approximation of spherical distances on Earth
export function geoSphericalDistance(a, b) {
var x = geoLonToMeters(a[0] - b[0], (a[1] + b[1]) / 2),
y = geoLatToMeters(a[1] - b[1]);
return Math.sqrt((x * x) + (y * y));
}
export function geoEdgeEqual(a, b) {
return (a[0] === b[0] && a[1] === b[1]) ||
(a[0] === b[1] && a[1] === b[0]);
}
// Return the counterclockwise angle in the range (-pi, pi)
// between the positive X axis and the line intersecting a and b.
export function geoAngle(a, b, projection) {
a = projection(a.loc);
b = projection(b.loc);
return Math.atan2(b[1] - a[1], b[0] - a[0]);
}
// Rotate all points counterclockwise around a pivot point by given angle
export function geoRotate(points, angle, around) {
return points.map(function(point) {
var radial = [point[0] - around[0], point[1] - around[1]];
return [
radial[0] * Math.cos(angle) - radial[1] * Math.sin(angle) + around[0],
radial[0] * Math.sin(angle) + radial[1] * Math.cos(angle) + around[1]
];
});
}
// Choose the edge with the minimal distance from `point` to its orthogonal
// projection onto that edge, if such a projection exists, or the distance to
// the closest vertex on that edge. Returns an object with the `index` of the
// chosen edge, the chosen `loc` on that edge, and the `distance` to to it.
export function geoChooseEdge(nodes, point, projection) {
var dist = geoEuclideanDistance,
points = nodes.map(function(n) { return projection(n.loc); }),
min = Infinity,
idx, loc;
function dot(p, q) {
return p[0] * q[0] + p[1] * q[1];
}
for (var i = 0; i < points.length - 1; i++) {
var o = points[i],
s = [points[i + 1][0] - o[0],
points[i + 1][1] - o[1]],
v = [point[0] - o[0],
point[1] - o[1]],
proj = dot(v, s) / dot(s, s),
p;
if (proj < 0) {
p = o;
} else if (proj > 1) {
p = points[i + 1];
} else {
p = [o[0] + proj * s[0], o[1] + proj * s[1]];
}
var d = dist(p, point);
if (d < min) {
min = d;
idx = i + 1;
loc = projection.invert(p);
}
}
return {
index: idx,
distance: min,
loc: loc
};
}
// Return the intersection point of 2 line segments.
// From https://github.com/pgkelley4/line-segments-intersect
// This uses the vector cross product approach described below:
// http://stackoverflow.com/a/565282/786339
export function geoLineIntersection(a, b) {
function subtractPoints(point1, point2) {
return [point1[0] - point2[0], point1[1] - point2[1]];
}
function crossProduct(point1, point2) {
return point1[0] * point2[1] - point1[1] * point2[0];
}
var p = [a[0][0], a[0][1]],
p2 = [a[1][0], a[1][1]],
q = [b[0][0], b[0][1]],
q2 = [b[1][0], b[1][1]],
r = subtractPoints(p2, p),
s = subtractPoints(q2, q),
uNumerator = crossProduct(subtractPoints(q, p), r),
denominator = crossProduct(r, s);
if (uNumerator && denominator) {
var u = uNumerator / denominator,
t = crossProduct(subtractPoints(q, p), s) / denominator;
if ((t >= 0) && (t <= 1) && (u >= 0) && (u <= 1)) {
return geoInterp(p, p2, t);
}
}
return null;
}
export function geoPathIntersections(path1, path2) {
var intersections = [];
for (var i = 0; i < path1.length - 1; i++) {
for (var j = 0; j < path2.length - 1; j++) {
var a = [ path1[i], path1[i+1] ],
b = [ path2[j], path2[j+1] ],
hit = geoLineIntersection(a, b);
if (hit) intersections.push(hit);
}
}
return intersections;
}
// Return whether point is contained in polygon.
//
// `point` should be a 2-item array of coordinates.
// `polygon` should be an array of 2-item arrays of coordinates.
//
// From https://github.com/substack/point-in-polygon.
// ray-casting algorithm based on
// http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
//
export function geoPointInPolygon(point, polygon) {
var x = point[0],
y = point[1],
inside = false;
for (var i = 0, j = polygon.length - 1; i < polygon.length; j = i++) {
var xi = polygon[i][0], yi = polygon[i][1];
var xj = polygon[j][0], yj = polygon[j][1];
var intersect = ((yi > y) !== (yj > y)) &&
(x < (xj - xi) * (y - yi) / (yj - yi) + xi);
if (intersect) inside = !inside;
}
return inside;
}
export function geoPolygonContainsPolygon(outer, inner) {
return _.every(inner, function(point) {
return geoPointInPolygon(point, outer);
});
}
export function geoPolygonIntersectsPolygon(outer, inner, checkSegments) {
function testSegments(outer, inner) {
for (var i = 0; i < outer.length - 1; i++) {
for (var j = 0; j < inner.length - 1; j++) {
var a = [ outer[i], outer[i+1] ],
b = [ inner[j], inner[j+1] ];
if (geoLineIntersection(a, b)) return true;
}
}
return false;
}
function testPoints(outer, inner) {
return _.some(inner, function(point) {
return geoPointInPolygon(point, outer);
});
}
return testPoints(outer, inner) || (!!checkSegments && testSegments(outer, inner));
}
export function geoPathLength(path) {
var length = 0;
for (var i = 0; i < path.length - 1; i++) {
length += geoEuclideanDistance(path[i], path[i + 1]);
}
return length;
}