fj-core 0.49.0

Early-stage b-rep CAD kernel.
Documentation 
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use crate::{
    objects::{HalfEdge, Shell},
    storage::Handle,
};

use super::BoundingVerticesOfHalfEdge;

/// Queries related to the sibling of a [`HalfEdge`]
pub trait SiblingOfHalfEdge {
    /// Indicate whether the provided half-edges are siblings
    fn are_siblings(&self, a: &Handle<HalfEdge>, b: &Handle<HalfEdge>) -> bool;

    /// Retrieve the sibling of this half-edge
    ///
    /// Returns `None`, if the provided half-edge is not part of the object this
    /// method is called on, or if the provided half-edge has no sibling within
    /// the object.
    fn get_sibling_of(
        &self,
        half_edge: &Handle<HalfEdge>,
    ) -> Option<Handle<HalfEdge>>;
}

impl SiblingOfHalfEdge for Shell {
    fn are_siblings(&self, a: &Handle<HalfEdge>, b: &Handle<HalfEdge>) -> bool {
        let same_curve = a.curve().id() == b.curve().id();
        let same_boundary = a.boundary() == b.boundary().reverse();
        let same_vertices = {
            let Some(a_vertices) = self.bounding_vertices_of_half_edge(a)
            else {
                return false;
            };
            let Some(b_vertices) = self.bounding_vertices_of_half_edge(b)
            else {
                return false;
            };

            a_vertices == b_vertices.reverse()
        };

        same_curve && same_boundary && same_vertices
    }

    fn get_sibling_of(
        &self,
        half_edge: &Handle<HalfEdge>,
    ) -> Option<Handle<HalfEdge>> {
        for face in self.faces() {
            for cycle in face.region().all_cycles() {
                for h in cycle.half_edges() {
                    if self.are_siblings(half_edge, h) {
                        return Some(h.clone());
                    }
                }
            }
        }

        None
    }
}