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/*
Copyright 2017 Martin Buck
This file is part of rust-3d.
rust-3d is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
rust-3d is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with rust-3d.  If not, see <http://www.gnu.org/licenses/>.
*/

//! HasDistanceTo trait used for types which have a defined distance towards another T.
//! Implementing HasDistanceTo<T> for U also implements HasDistanceTo<U> for T

use prelude::*;

/// HasDistanceTo trait used for types which have a defined distance towards another T.
/// Implementing HasDistanceTo<T> for U also implements HasDistanceTo<U> for T
pub trait HasDistanceTo<T> {
    /// Should return the sqr distance to other
    fn sqr_distance(&self, other: &T) -> NonNegative;
    /// The distance to other
    fn distance(&self, other: &T) -> NonNegative {
        self.sqr_distance(other).sqrt()
    }
}

/*
@todo currently breaks A.distance(A). Possible, once specialization hits stable
impl<T, U> HasDistanceTo<T> for U where
    T: HasDistanceTo<U> {

    fn sqr_distance(&self, other: &T) -> NonNegative {
        other.sqr_distance(self)
    }
}*/