conspire 0.7.2

The Rust interface to conspire.
Documentation 
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#[cfg(test)]
mod test;

use super::{Class, DIRECTIONS, topology::element_faces};
use crate::{
    geometry::{
        Coordinate, Coordinates, CoordinatesRef,
        bbox::BoundingBox,
        mesh::{Mesh, tessellation::D, tessellation::Tessellation},
    },
    math::Tensor,
};
use std::collections::{HashMap, hash_map::Entry};

impl Tessellation {
    pub fn classify(&self, mesh: &Mesh<D>) -> Vec<Class> {
        let surface = self.mesh();
        let surface_coordinates = surface.coordinates();
        let elements: Vec<&[usize]> = surface.connectivities().iter().flatten().collect();
        let normals: CoordinatesRef<'_, D> = self.normals().iter().flatten().collect();
        let directions = DIRECTIONS.map(|direction| direction.normalized());
        let bvh = self.bvh();
        let coordinates = mesh.coordinates();
        let number_of_elements = mesh.number_of_elements();
        let mut cut = vec![false; number_of_elements];
        mesh.iter()
            .flat_map(|block| {
                block
                    .iter()
                    .map(move |element| block.element_nodes(element))
            })
            .zip(cut.iter_mut())
            .for_each(|(nodes, flag)| {
                let bbox: BoundingBox<D> = nodes
                    .iter()
                    .map(|&node| &coordinates[node])
                    .collect::<CoordinatesRef<'_, D>>()
                    .into();
                *flag = bvh.overlapping(&bbox).into_iter().any(|triangle| {
                    let nodes = elements[triangle];
                    bbox.overlaps_triangle(
                        &surface_coordinates[nodes[0]],
                        &surface_coordinates[nodes[1]],
                        &surface_coordinates[nodes[2]],
                    )
                })
            });
        let mut faces = HashMap::new();
        let mut neighbors: Vec<Vec<usize>> = vec![Vec::new(); number_of_elements];
        let mut offset = 0;
        mesh.iter().for_each(|block| {
            block.iter().enumerate().for_each(|(local, element)| {
                let index = offset + local;
                if !cut[index] {
                    element_faces(block, element).into_iter().for_each(|face| {
                        let mut key = face;
                        key.sort_unstable();
                        match faces.entry(key) {
                            Entry::Occupied(entry) => {
                                let other = *entry.get();
                                neighbors[index].push(other);
                                neighbors[other].push(index);
                            }
                            Entry::Vacant(slot) => {
                                slot.insert(index);
                            }
                        }
                    })
                }
            });
            offset += block.number_of_elements();
        });
        let centroids = mesh.centroids();
        let mut classes: Vec<Class> = cut
            .iter()
            .map(|&flag| if flag { Class::Cut } else { Class::Outside })
            .collect();
        let mut visited = cut;
        let mut stack = Vec::new();
        (0..number_of_elements).for_each(|seed| {
            if !visited[seed] {
                let class = if self.encloses(
                    &centroids[seed],
                    surface_coordinates,
                    &elements,
                    &normals,
                    &directions,
                ) {
                    Class::Inside
                } else {
                    Class::Outside
                };
                visited[seed] = true;
                stack.push(seed);
                while let Some(index) = stack.pop() {
                    classes[index] = class;
                    neighbors[index].iter().for_each(|&next| {
                        if !visited[next] {
                            visited[next] = true;
                            stack.push(next);
                        }
                    })
                }
            }
        });
        classes
    }
    pub(super) fn encloses(
        &self,
        point: &Coordinate<D>,
        surface_coordinates: &Coordinates<D>,
        elements: &[&[usize]],
        normals: &CoordinatesRef<'_, D>,
        directions: &[Coordinate<D>; 3],
    ) -> bool {
        directions
            .iter()
            .find_map(|direction| {
                let ray = (point.clone(), direction.clone()).into();
                match self.bvh().intersect(&ray, surface_coordinates, elements) {
                    None => Some(false),
                    Some(hit) => {
                        let normal = &normals[hit.index()];
                        let cosine = (direction * normal) / normal.norm();
                        (cosine.abs() > super::GRAZING_TOLERANCE).then_some(cosine > 0.0)
                    }
                }
            })
            .unwrap_or(false)
    }
}