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Contents
// @import parallel1
function rectangularPolyconic(φ0) {
var sinφ0 = Math.sin(φ0);
function forward(λ, φ) {
var A = sinφ0 ? Math.tan(λ * sinφ0 / 2) / sinφ0 : λ / 2;
if (!φ) return [2 * A, -φ0];
var E = 2 * Math.atan(A * Math.sin(φ)),
cotφ = 1 / Math.tan(φ);
return [
Math.sin(E) * cotφ,
φ + (1 - Math.cos(E)) * cotφ - φ0
];
}
// TODO return null for points outside outline.
forward.invert = function(x, y) {
if (Math.abs(y += φ0) < ε) return [sinφ0 ? 2 * Math.atan(sinφ0 * x / 2) / sinφ0 : x, 0];
var k = x * x + y * y,
φ = 0,
i = 10, δ;
do {
var tanφ = Math.tan(φ),
secφ = 1 / Math.cos(φ),
j = k - 2 * y * φ + φ * φ;
φ -= δ = (tanφ * j + 2 * (φ - y)) / (2 + j * secφ * secφ + 2 * (φ - y) * tanφ);
} while (Math.abs(δ) > ε && --i > 0);
var E = x * (tanφ = Math.tan(φ)),
A = Math.tan(Math.abs(y) < Math.abs(φ + 1 / tanφ) ? asin(E) * .5 : acos(E) * .5 + π / 4) / Math.sin(φ);
return [
sinφ0 ? 2 * Math.atan(sinφ0 * A) / sinφ0 : 2 * A,
φ
];
};
return forward;
}
(d3.geo.rectangularPolyconic = function() { return parallel1Projection(rectangularPolyconic); }).raw = rectangularPolyconic;
Version data entries
2 entries across 2 versions & 1 rubygems