32 lines
888 B
Java
32 lines
888 B
Java
import {geoProjection as projection} from "d3-geo";
|
|
import {abs, asin, cos, epsilon, halfPi, pi, sin, sqrt} from "./math";
|
|
|
|
export function mtFlatPolarSinusoidalRaw(lambda, phi) {
|
|
var A = sqrt(6 / (4 + pi)),
|
|
k = (1 + pi / 4) * sin(phi),
|
|
theta = phi / 2;
|
|
for (var i = 0, delta; i < 25; i++) {
|
|
theta -= delta = (theta / 2 + sin(theta) - k) / (0.5 + cos(theta));
|
|
if (abs(delta) < epsilon) break;
|
|
}
|
|
return [
|
|
A * (0.5 + cos(theta)) * lambda / 1.5,
|
|
A * theta
|
|
];
|
|
}
|
|
|
|
mtFlatPolarSinusoidalRaw.invert = function(x, y) {
|
|
var A = sqrt(6 / (4 + pi)),
|
|
theta = y / A;
|
|
if (abs(abs(theta) - halfPi) < epsilon) theta = theta < 0 ? -halfPi : halfPi;
|
|
return [
|
|
1.5 * x / (A * (0.5 + cos(theta))),
|
|
asin((theta / 2 + sin(theta)) / (1 + pi / 4))
|
|
];
|
|
};
|
|
|
|
export default function() {
|
|
return projection(mtFlatPolarSinusoidalRaw)
|
|
.scale(166.518);
|
|
}
|