dcel 0.8.14

Implementation of doubly-connected edge list.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223

// SPDX-FileCopyrightText: 2026 dcel contributors
//
// SPDX-License-Identifier: MIT OR Apache-2.0

use maplike::{Get, Insert, Push};

use crate::{Dcel, EdgeId, Face, FaceId, HalfEdge, Vertex, VertexId};

impl<
    VW: Clone,
    HEW: Clone + Default,
    FW: Clone + Default,
    VC: Get<usize, Value = Vertex<VW>> + Insert<usize> + Push<usize>,
    HEC: Get<usize, Value = HalfEdge<HEW>> + Insert<usize> + Push<usize>,
    FC: Get<usize, Value = Face<FW>> + Insert<usize> + Push<usize>,
> Dcel<VW, HEW, FW, VC, HEC, FC>
{
    /// Partition a face into triangles by inserting a vertex inside and adding
    /// edges between it and the original face's vertices.
    ///
    /// The original face is reused for the first triangle. New faces are
    /// created for all the other triangles.
    ///
    /// Returns the new vertex id together with the ids of all the newly created
    /// edges and faces (the reused already existing edges and face are not
    /// included).
    pub fn triangulate_face_around_point(
        &mut self,
        perimeter_face: FaceId,
        inner_vertex_weight: VW,
    ) -> (VertexId, Vec<EdgeId>, Vec<FaceId>) {
        let perimeter_vertex_count = self.face_vertices(perimeter_face).count();

        self.triangulate_face_around_point_with_all_weights(
            perimeter_face,
            inner_vertex_weight,
            std::iter::repeat_n(Default::default(), perimeter_vertex_count),
            std::iter::repeat_n(Default::default(), perimeter_vertex_count),
        )
    }

    /// Partition a face into triangles by connecting an existing vertex to all
    /// of the face's boundary vertices.
    ///
    /// The original face is reused for the first triangle. New faces are
    /// created for all the other triangles.
    ///
    /// Returns the ids of all the newly created edges and faces (the reused
    /// already existing edges and face are not included).
    pub fn fan_triangulate(
        &mut self,
        perimeter_face: FaceId,
        apex: VertexId,
    ) -> (Vec<EdgeId>, Vec<FaceId>) {
        let perimeter_vertex_count = self.face_vertices(perimeter_face).count();

        self.fan_triangulate_with_all_weights(
            perimeter_face,
            apex,
            std::iter::repeat_n(Default::default(), perimeter_vertex_count),
            std::iter::repeat_n(Default::default(), perimeter_vertex_count),
        )
    }
}

impl<
    VW: Clone,
    HEW: Clone,
    FW: Clone,
    VC: Get<usize, Value = Vertex<VW>> + Insert<usize> + Push<usize>,
    HEC: Get<usize, Value = HalfEdge<HEW>> + Insert<usize> + Push<usize>,
    FC: Get<usize, Value = Face<FW>> + Insert<usize> + Push<usize>,
> Dcel<VW, HEW, FW, VC, HEC, FC>
{
    /// Partition a face into triangles by inserting a vertex inside and adding
    /// edges between it and the original face's vertices, with all edge and
    /// triangle face weights specified.
    ///
    /// The original face is reused for the first triangle. New faces are
    /// created for all the other triangles.
    ///
    /// Returns the new vertex id together with the ids of all the newly created
    /// edges and faces (the reused already existing edges and face are not
    /// included).
    pub fn triangulate_face_around_point_with_all_weights(
        &mut self,
        perimeter_face: FaceId,
        inner_vertex_weight: VW,
        inner_edge_weights: impl IntoIterator<Item = (HEW, HEW)>,
        triangle_face_weights: impl IntoIterator<Item = FW>,
    ) -> (VertexId, Vec<EdgeId>, Vec<FaceId>) {
        let inner_vertex = self.add_unwired_vertex(inner_vertex_weight);
        let (new_edges, new_faces) = self.fan_triangulate_with_all_weights(
            perimeter_face,
            inner_vertex,
            inner_edge_weights,
            triangle_face_weights,
        );

        (inner_vertex, new_edges, new_faces)
    }

    /// Partition a face into triangles by connecting an existing vertex to all
    /// of the face's boundary vertices, with all edge and triangle face weights
    /// specified.
    ///
    /// The original face is reused for the first triangle. New faces are
    /// created for all the other triangles.
    ///
    /// Returns the ids of all the newly created edges and faces (the reused
    /// already existing edges and face are not included).
    pub fn fan_triangulate_with_all_weights(
        &mut self,
        perimeter_face: FaceId,
        apex: VertexId,
        inner_edge_weights: impl IntoIterator<Item = (HEW, HEW)>,
        triangle_face_weights: impl IntoIterator<Item = FW>,
    ) -> (Vec<EdgeId>, Vec<FaceId>) {
        let new_faces = self.add_unwired_triangulation_faces(perimeter_face, triangle_face_weights);

        let mut triangle_faces = vec![perimeter_face];
        triangle_faces.extend(new_faces.clone());

        let new_edges = self.add_unwired_triangulation_edges(
            perimeter_face,
            apex,
            &triangle_faces,
            inner_edge_weights,
        );
        self.wire_triangulation_faces_edges_vertices(perimeter_face, &new_edges);

        (new_edges, new_faces)
    }

    fn add_unwired_triangulation_faces(
        &mut self,
        first_face: FaceId,
        triangle_face_weights: impl IntoIterator<Item = FW>,
    ) -> Vec<FaceId> {
        let mut new_faces = vec![];

        let mut face_weights_iter = triangle_face_weights.into_iter();
        self.faces.insert(
            first_face.id(),
            Face {
                representative: self.faces.get(&first_face.id()).unwrap().representative,
                weight: face_weights_iter.next().unwrap(),
            },
        );

        for face_weight in face_weights_iter {
            new_faces.push(self.add_unwired_face(face_weight));
        }

        new_faces
    }

    fn add_unwired_triangulation_edges(
        &mut self,
        perimeter_face: FaceId,
        inner_vertex: VertexId,
        triangle_faces: &[FaceId],
        inner_edge_weights: impl IntoIterator<Item = (HEW, HEW)>,
    ) -> Vec<EdgeId> {
        let mut inner_edge_weights = inner_edge_weights.into_iter();
        let mut face_vertices_walker = self.face_vertices(perimeter_face).walker();
        let mut edges = vec![];

        let mut i: usize = 0;

        while let Some(perimeter_vertex) = face_vertices_walker.next(self) {
            let (weight, twin_weight) = inner_edge_weights.next().unwrap();

            let prev_face = if i == 0 {
                // Wrap to avoid negative index.
                triangle_faces[triangle_faces.len() - 1]
            } else {
                triangle_faces[i - 1]
            };

            let (forward, _backward) = self.add_unwired_edge(
                perimeter_vertex,
                inner_vertex,
                prev_face,
                triangle_faces[i],
                weight,
                twin_weight,
            );
            edges.push(self.full_edge(forward));

            i += 1;
        }

        edges
    }

    fn wire_triangulation_faces_edges_vertices(
        &mut self,
        perimeter_face: FaceId,
        inner_edges: &[EdgeId],
    ) {
        let inner_edges_circular_tuple_windows = inner_edges
            .iter()
            .zip(inner_edges.iter().skip(1).chain(inner_edges.iter().take(1)));
        let mut perimeter_half_edges_walker = self.face_half_edges(perimeter_face).walker();

        for (inner_edge, next_inner_edge) in inner_edges_circular_tuple_windows {
            let perimeter_half_edge = perimeter_half_edges_walker.next(self).unwrap();
            let triangle_face = self.incident_face(inner_edge.greater());

            self.wire_inner_half_edge_chain(
                triangle_face,
                &[
                    perimeter_half_edge,
                    next_inner_edge.lesser(),
                    inner_edge.greater(),
                ],
            );
        }
    }
}

// TODO: Tests.