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37 lines
911 B
37 lines
911 B
1 year ago
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import {asin, atan2, cos, degrees, haversin, radians, sin, sqrt} from "./math";
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export default function(a, b) {
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var x0 = a[0] * radians,
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y0 = a[1] * radians,
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x1 = b[0] * radians,
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y1 = b[1] * radians,
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cy0 = cos(y0),
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sy0 = sin(y0),
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cy1 = cos(y1),
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sy1 = sin(y1),
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kx0 = cy0 * cos(x0),
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ky0 = cy0 * sin(x0),
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kx1 = cy1 * cos(x1),
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ky1 = cy1 * sin(x1),
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d = 2 * asin(sqrt(haversin(y1 - y0) + cy0 * cy1 * haversin(x1 - x0))),
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k = sin(d);
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var interpolate = d ? function(t) {
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var B = sin(t *= d) / k,
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A = sin(d - t) / k,
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x = A * kx0 + B * kx1,
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y = A * ky0 + B * ky1,
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z = A * sy0 + B * sy1;
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return [
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atan2(y, x) * degrees,
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atan2(z, sqrt(x * x + y * y)) * degrees
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];
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} : function() {
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return [x0 * degrees, y0 * degrees];
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};
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interpolate.distance = d;
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return interpolate;
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}
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