Sha256: aad88587580935ec0247fa100758f5716d50d5069bb13c0c9178dd207e7f2c2b
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Versions: 4
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Stored size: 1.45 KB
Contents
import "projection";
import "aitoff";
function winkel3(λ, φ) {
var coordinates = aitoff(λ, φ);
return [
(coordinates[0] + λ * 2 / π) / 2,
(coordinates[1] + φ) / 2
];
}
winkel3.invert = function(x, y) {
var λ = x, φ = y, i = 25;
do {
var cosφ = Math.cos(φ),
sinφ = Math.sin(φ),
sin_2φ = Math.sin(2 * φ),
sin2φ = sinφ * sinφ,
cos2φ = cosφ * cosφ,
sinλ = Math.sin(λ),
cosλ_2 = Math.cos(λ / 2),
sinλ_2 = Math.sin(λ / 2),
sin2λ_2 = sinλ_2 * sinλ_2,
C = 1 - cos2φ * cosλ_2 * cosλ_2,
E = C ? acos(cosφ * cosλ_2) * Math.sqrt(F = 1 / C) : F = 0,
F,
fx = .5 * (2 * E * cosφ * sinλ_2 + λ * 2 / π) - x,
fy = .5 * (E * sinφ + φ) - y,
δxδλ = .5 * F * (cos2φ * sin2λ_2 + E * cosφ * cosλ_2 * sin2φ) + .5 * 2 / π,
δxδφ = F * (sinλ * sin_2φ / 4 - E * sinφ * sinλ_2),
δyδλ = .125 * F * (sin_2φ * sinλ_2 - E * sinφ * cos2φ * sinλ),
δyδφ = .5 * F * (sin2φ * cosλ_2 + E * sin2λ_2 * cosφ) + .5,
denominator = δxδφ * δyδλ - δyδφ * δxδλ,
δλ = (fy * δxδφ - fx * δyδφ) / denominator,
δφ = (fx * δyδλ - fy * δxδλ) / denominator;
λ -= δλ, φ -= δφ;
} while ((Math.abs(δλ) > ε || Math.abs(δφ) > ε) && --i > 0);
return [λ, φ];
};
(d3.geo.winkel3 = function() { return projection(winkel3); }).raw = winkel3;
Version data entries
4 entries across 4 versions & 1 rubygems