function interpolateProjection(raw0, raw1) {
const mutate = d3.geoProjectionMutator((t) => (x, y) => {
const [x0, y0] = raw0(x, y),
[x1, y1] = raw1(x, y);
return [x0 + t * (x1 - x0), y0 + t * (y1 - y0)];
});
let t = 0;
return Object.assign(mutate(t), {
alpha(_) {
return arguments.length ? mutate((t = +_)) : t;
}
});
}