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Contents
import "projection";
function quincuncialProjection(projectHemisphere) {
var dx = projectHemisphere(π / 2, 0)[0] - projectHemisphere(-π / 2, 0)[0];
function projection() {
var quincuncial = false,
m = projectionMutator(projectAt),
p = m(quincuncial);
p.quincuncial = function(_) {
if (!arguments.length) return quincuncial;
return m(quincuncial = !!_);
};
return p;
}
function projectAt(quincuncial) {
var forward = quincuncial ? function(λ, φ) {
var t = Math.abs(λ) < π / 2,
p = projectHemisphere(t ? λ : λ > 0 ? λ - π : λ + π, φ);
var x = (p[0] - p[1]) * Math.SQRT1_2,
y = (p[0] + p[1]) * Math.SQRT1_2;
if (t) return [x, y];
var d = dx * Math.SQRT1_2,
s = x > 0 ^ y > 0 ? -1 : 1;
return [s * x - sgn(y) * d, s * y - sgn(x) * d];
} : function(λ, φ) {
var s = λ > 0 ? -.5 : .5,
point = projectHemisphere(λ + s * π, φ);
point[0] -= s * dx;
return point;
};
if (projectHemisphere.invert) forward.invert = quincuncial ? function(x0, y0) {
var x = (x0 + y0) * Math.SQRT1_2,
y = (y0 - x0) * Math.SQRT1_2,
t = Math.abs(x) < .5 * dx && Math.abs(y) < .5 * dx;
if (!t) {
var d = dx * Math.SQRT1_2,
s = x > 0 ^ y > 0 ? -1 : 1,
x1 = -s * (x0 + (y > 0 ? 1 : -1) * d),
y1 = -s * (y0 + (x > 0 ? 1 : -1) * d);
x = (-x1 - y1) * Math.SQRT1_2;
y = (x1 - y1) * Math.SQRT1_2;
}
var p = projectHemisphere.invert(x, y);
if (!t) p[0] += x > 0 ? π : -π;
return p;
} : function(x, y) {
var s = x > 0 ? -.5 : .5,
location = projectHemisphere.invert(x + s * dx, y),
λ = location[0] - s * π;
if (λ < -π) λ += 2 * π;
else if (λ > π) λ -= 2 * π;
location[0] = λ;
return location;
};
return forward;
}
projection.raw = projectAt;
return projection;
}
Version data entries
4 entries across 4 versions & 1 rubygems