del-geo 0.1.20

2D/3D geometry utility codes
Documentation 
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//! methods for 2D Axis-aligned Bounding Box (AABB)

use num_traits::AsPrimitive;

pub fn from_vtx2xy<Real>(
    vtx2xy: &[Real]) -> [Real;4]
where Real: num_traits::Float
{
    let mut aabb = [vtx2xy[0], vtx2xy[1], vtx2xy[0], vtx2xy[1]];
    vtx2xy.chunks(2).skip(1).for_each(
        |v| {
            aabb[0] = if v[0] < aabb[0] { v[0] } else { aabb[0] };
            aabb[1] = if v[1] < aabb[1] { v[1] } else { aabb[1] };
            aabb[2] = if v[0] > aabb[2] { v[0] } else { aabb[2] };
            aabb[3] = if v[1] > aabb[3] { v[1] } else { aabb[3] };
        }
    );
    aabb
}

/// signed distance from axis-aligned bounding box
/// * `pos_in` - where the signed distance is evaluated
/// * `x_min` - bounding box's x-coordinate minimum
/// * `x_max` - bounding box's x-coordinate maximum
/// * `y_min` - bounding box's y-coordinate minimum
/// * `y_max` - bounding box's y-coordinate maximum
/// * signed distance (inside is negative)
pub fn signed_distance_aabb<Real>(
    pos_in: nalgebra::Vector2::<Real>,
    min0: nalgebra::Vector2::<Real>,
    max0: nalgebra::Vector2::<Real>) -> Real
    where Real: nalgebra::RealField + Copy,
          f64: AsPrimitive<Real>
{
    let half = 0.5_f64.as_();
    let x_center = (max0.x + min0.x) * half;
    let y_center = (max0.y + min0.y) * half;
    let x_dist = (pos_in.x - x_center).abs() - (max0.x - min0.x) * half;
    let y_dist = (pos_in.y - y_center).abs() - (max0.y - min0.y) * half;
    x_dist.max(y_dist)
}

pub fn from_vtx2vec<T>(
    vtx2vec: &[nalgebra::Vector2<T>])
    -> [T;4]
    where T: nalgebra::RealField + Copy
{
    let mut aabb = [vtx2vec[0][0], vtx2vec[0][1], vtx2vec[0][0], vtx2vec[0][1]];
    for xy in vtx2vec.iter().skip(1) {
        if xy[0] < aabb[0] { aabb[0] = xy[0]; }
        if xy[1] < aabb[1] { aabb[1] = xy[1]; }
        if xy[0] > aabb[2] { aabb[2] = xy[0]; }
        if xy[1] > aabb[3] { aabb[3] = xy[1]; }
    }
    aabb
}