spherical-cow 0.1.3

use crate::errors::SphericalCowError as Error;
use crate::shapes::Sphere;
use crate::Container;

#[derive(PartialEq, Debug, Clone)]
/// Constructs a cuboid centered at the origin in Euclidean space.
pub struct Cuboid {
    /// Central point in space where this sphere is located.
    pub half_extents: Vec<f32>,
}

impl Cuboid {
    /// Creates a new box from its `half_extents`. Half-extents are the box half-width along each
    /// axis, all of which must be greater than 0.
    pub fn new(extent_x: f32, extent_y: f32, extent_z: f32) -> Result<Cuboid, Error> {
        //TODO: Should also have an orientation vector so this can be arbitrarily rotated too.
        if extent_x <= 0.0 || extent_y <= 0.0 || extent_z <= 0.0 {
            Err(Error::NegativeExtents)
        } else {
            Ok(Cuboid {
                half_extents: vec![extent_x, extent_y, extent_z],
            })
        }
    }

    /// Similar than calling `new`, but the `half_extents` are contained within a vector.
    pub fn from_vec(half_extents: Vec<f32>) -> Result<Cuboid, Error> {
        if half_extents.iter().any(|he| *he <= 0.0) {
            Err(Error::NegativeExtents)
        } else {
            Ok(Cuboid { half_extents })
        }
    }
}

impl Container for Cuboid {
    /// Checks if sphere exists inside the current bounding box.
    fn contains(&self, sphere: &Sphere) -> bool {
        // Sphere's center point plus its radius must be less than all three half_extents
        self.half_extents
            .iter()
            .zip(sphere.center.coords.iter())
            .all(|(extent, sphere_extent)| sphere_extent.abs() + sphere.radius <= *extent)
    }

    /// Calculates the volume of this cuboid in normalised units.
    fn volume(&self) -> f32 {
        self.half_extents
            .iter()
            .map(|half_extent| 2. * half_extent)
            .product()
    }
}