Intermediate points on great circle route between two Points

[JivanRoquet]

One interesting addition to the library would be the ability, given two distinct initial points anywhere on Earth, to compute any intermediate point located on the Great Circle path between the two initial points.

impl<T> HaversineIntermediate<T> for Point<T>
where T: Float + Primivite
{
    fn haversine_intermediate(&self, other: &Point<T>, f: T) -> Point<T> {
        // return the intermediate point on the Great Circle between self and other
        // where f is the fraction along Great Circle route
        // (f = 0.0 returns self , f = 1.0 returns other)
    }
}

let p1 = Point::new(50.0, 20.0);
let p2 = Point::new(20.0, 10.0);

let i10  = p1.haversine_intermediate(p2, 0.1); // at 10% of the way between p1 and p2
let i20  = p1.haversine_intermediate(p2, 0.2); // at 20% of the way between p1 and p2
let i50  = p1.haversine_intermediate(p2, 0.5); // halfway between p1 and p2

let i0   = p1.haversine_intermediate(p2, 0.0);
let i100 = p1.haversine_intermediate(p2, 1.0);

assert_eq!(i0, p1);
assert_eq!(i100, p2);

Resources:

http://www.edwilliams.org/avform.htm#Intermediate
http://fraserchapman.blogspot.co.uk/2008/09/intermediate-points-on-great-circle.html

[JivanRoquet]

See PR #230

[JivanRoquet]

Feature: adding a method returning a sequence of points given a maximum distance between points.

Spec draft:

fn haversine_intermediate_fill(&self, other: &Point<T>, max_dist: T, include_ends: bool) -> Vec<Point<T>> {
    // return all the waypoints between and including self and other,
    // so that no two consecutive waypoints are distant of more than max_dist
    // and pick the waypoints so that they are evenly distributed along the path
}