Function iron_shapes_booleanop::connectivity_extraction::extract_connectivity

pub fn extract_connectivity<'a, I, T, ID>(
    edge_intersection: I,
    polygon_edges: impl Iterator<Item = (Edge<T>, ID)>,
    polygon_semantics: PolygonSemantics
) -> impl Iterator<Item = (ID, ID, Point<T>)>where
    I: Fn(&Edge<T>, &Edge<T>) -> EdgeIntersection<T, T, Edge<T>>,
    T: CoordinateType + Debug + 'a,
    ID: Clone + Hash + Eq,

Extract a connectivity of a set of polygons. The polygons are supplied in the form of an interator over the polygon edges. If the supplied edges are inconsistent, e.g. don’t form closed polygon shapes, then the result is undefined.

Each edge must be labelled with the identifier of the polygon it belongs to. Connectivity is encoded as an iterator over multi-graph edges. Each consists of the IDs of the two touching polygons and a location where the both polygons touch. Edges can appear many times.

Examples

use iron_shapes::prelude::*;
use iron_shapes::traits::Translate;
use iron_shapes_booleanop::connectivity_extraction::*;
use iron_shapes_booleanop::*;
use std::collections::HashSet;

let p0 = Polygon::from(vec![(0f64, 0.), (2., 0.), (2., 2.), (0., 2.)]);
let p1 = p0.translate((1., 1.).into());
let p2 = p0.translate((0., 100.).into()); // Far away, not touching anything.

let polygons = vec![p0, p1, p2];

// Convert the polygons into edges labelled with an identifier of their polygon.
let polygon_edges = polygons
    .iter()
    .enumerate()
    .flat_map(|(id, polygon)| polygon.all_edges_iter().map(move |e| (e, id)));

let connectivity_graph = extract_connectivity_graph(
    edge_intersection_float,
    polygon_edges,
    PolygonSemantics::Union,
);

// p0 and p1 are connected.
assert_eq!(connectivity_graph.get(&0), Some(&HashSet::from([1])));
assert_eq!(connectivity_graph.get(&1), Some(&HashSet::from([0])));

// p2 is not connected to any other polygon.
assert_eq!(connectivity_graph.get(&2), None);