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