math_utils/geometry/mesh/
edge_triangle.rs

1//! Edge-triangle meshes
2// code from GeometricTools:
3// <https://github.com/davideberly/GeometricTools/blob/f78dd0b65bc3a0a4723586de6991dd2c339b08ad/GTE/Mathematics/ETManifoldMesh.h>
4// <https://github.com/davideberly/GeometricTools/blob/f78dd0b65bc3a0a4723586de6991dd2c339b08ad/GTE/Mathematics/VETManifoldMesh.h>
5
6use std::collections::{BTreeMap, BTreeSet};
7
8#[derive(Default)]
9pub struct EdgeTriangleMesh {
10  edges     : BTreeMap <EdgeKey,     Edge>,
11  triangles : BTreeMap <TriangleKey, Triangle>,
12}
13
14#[derive(Default)]
15pub struct VertexEdgeTriangleMesh {
16  et_mesh  : EdgeTriangleMesh,
17  vertices : BTreeMap <u32, Vertex>
18}
19
20/// Note edge-keys are *un-ordered*
21#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
22pub struct EdgeKey (u32, u32);
23#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
24pub struct TriangleKey (u32, u32, u32);
25
26#[derive(Clone, Eq, Ord, PartialEq, PartialOrd)]
27pub struct Vertex {
28  index              : u32,
29  adjacent_vertices  : BTreeSet <u32>,
30  adjacent_edges     : BTreeSet <EdgeKey>,
31  adjacent_triangles : BTreeSet <TriangleKey>
32}
33
34#[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
35pub struct Edge {
36  vertices  : [u32; 2],
37  triangles : [Option <TriangleKey>; 2]
38}
39
40#[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
41pub struct Triangle {
42  /// Vertices listed in counter-clockwise order
43  vertices           : [u32; 3],
44  edges              : [Option <EdgeKey>; 3],
45  /// Triangle `i` points to the adjecent triangle sharing edge `i`
46  adjacent_triangles : [Option <TriangleKey>; 3],
47}
48
49impl EdgeTriangleMesh {
50  #[inline]
51  pub fn get_edge (&self, key : &EdgeKey) -> Option <&Edge> {
52    self.edges.get (key)
53  }
54  #[inline]
55  pub fn get_triangle (&self, key : &TriangleKey) -> Option <&Triangle> {
56    self.triangles.get (key)
57  }
58  /// Returns None if triangle already exists in the mesh
59  pub fn insert (&mut self, v0 : u32, v1 : u32, v2 : u32) -> Option <Triangle> {
60    self.insert_ (v0, v1, v2).map (|inserted| inserted.1)
61  }
62  fn insert_ (&mut self, v0 : u32, v1 : u32, v2 : u32)
63    -> Option <(TriangleKey, Triangle)>
64  {
65    let triangle_key = TriangleKey (v0, v1, v2);
66    if self.triangles.contains_key (&triangle_key) {
67      return None
68    }
69    let mut triangle = Triangle::new (v0, v1, v2);
70    let mut i0 = 2;
71    let mut i1 = 0;
72    while i1 < 3 {
73      let edge_key = EdgeKey::new (triangle.vertices[i0], triangle.vertices[i1]);
74      if let Some (mut edge) = self.edges.get (&edge_key).cloned() {
75        // TODO: the original implementation has a "manifold" check here
76        if edge.triangles[1].is_some() {
77          return None
78        }
79        edge.triangles[1] = Some (triangle_key);
80        let adjacent_key  = edge.triangles[0].unwrap();
81        let adjacent      = self.triangles.get_mut (&adjacent_key).unwrap();
82        for (i, e_key) in adjacent.edges.iter().enumerate() {
83          if e_key == &Some (edge_key) {
84            adjacent.adjacent_triangles[i] = Some (triangle_key);
85            break
86          }
87        }
88        triangle.edges[i0] = Some (edge_key);
89        triangle.adjacent_triangles[i0] = Some (adjacent_key);
90        *self.edges.get_mut (&edge_key).unwrap() = edge;
91      } else {
92        let mut new_edge = Edge::new (edge_key.0, edge_key.1);
93        new_edge.triangles[0] = Some (triangle_key);
94        triangle.edges[i0]    = Some (edge_key);
95        let _inserted = self.edges.insert (edge_key, new_edge);
96        debug_assert!(_inserted.is_none());
97      }
98      // iter
99      i0 = i1;
100      i1 += 1;
101    }
102    let _inserted = self.triangles.insert (triangle_key, triangle);
103    debug_assert!(_inserted.is_none());
104    Some ((triangle_key, triangle))
105  }
106
107  pub fn remove (&mut self, v0 : u32, v1 : u32, v2 : u32) -> bool {
108    let triangle_key = TriangleKey (v0, v1, v2);
109    if let Some (triangle) = self.triangles.remove (&triangle_key) {
110      for (i, edge_key) in triangle.edges.iter().map (|k| k.unwrap()).enumerate() {
111        let edge = self.edges.get_mut (&edge_key).unwrap();
112        if edge.triangles[0] == Some (triangle_key) {
113          edge.triangles[0] = edge.triangles[1];
114          edge.triangles[1] = None;
115        } else if edge.triangles[1] == Some (triangle_key) {
116          edge.triangles[1] = None;
117        } else {
118          unreachable!()
119        }
120        if edge.triangles[0].is_none() && edge.triangles[1].is_none() {
121          self.edges.remove (&edge_key);
122        }
123        if let Some (adjacent_key) = triangle.adjacent_triangles[i] {
124          let adjacent = self.triangles.get_mut (&adjacent_key).unwrap();
125          for key in adjacent.adjacent_triangles.iter_mut() {
126            if key == &Some (triangle_key) {
127              *key = None;
128              break
129            }
130          }
131        }
132      }
133      true
134    } else {
135      false
136    }
137  }
138
139  // TODO: more methods
140}
141
142impl VertexEdgeTriangleMesh {
143  #[inline]
144  pub fn get_vertex (&self, index : u32) -> Option <&Vertex> {
145    self.vertices.get (&index)
146  }
147
148  #[inline]
149  pub fn vertices (&self) -> &BTreeMap <u32, Vertex> {
150    &self.vertices
151  }
152
153  /// Returns None if triangle already exists in the mesh
154  pub fn insert (&mut self, v0 : u32, v1 : u32, v2 : u32) -> Option <Triangle> {
155    let (triangle_key, triangle) = self.et_mesh.insert_ (v0, v1, v2)?;
156    for index in triangle.vertices.iter() {
157      let vertex = self.vertices.entry (*index).or_insert_with (|| Vertex::new (*index));
158      vertex.adjacent_triangles.insert (triangle_key);
159      for edge_key in triangle.edges.iter().map (|k| k.unwrap()) {
160        let edge = self.et_mesh.edges.get (&edge_key).unwrap();
161        if edge.vertices[0] == *index {
162          vertex.adjacent_vertices.insert (edge.vertices[1]);
163          vertex.adjacent_edges.insert (edge_key);
164        } else if edge.vertices[1] == *index {
165          vertex.adjacent_vertices.insert (edge.vertices[0]);
166          vertex.adjacent_edges.insert (edge_key);
167        }
168      }
169    }
170    Some (triangle)
171  }
172
173  pub fn remove (&mut self, v0 : u32, v1 : u32, v2 : u32) -> bool {
174    let triangle_key = TriangleKey (v0, v1, v2);
175    if let Some (triangle) = self.et_mesh.triangles.get (&triangle_key) {
176      for index in triangle.vertices.iter() {
177        let vertex = self.vertices.get_mut (index).unwrap();
178        for edge_key in triangle.edges.iter().map (|k| k.unwrap()) {
179          let edge = self.et_mesh.edges.get (&edge_key).unwrap();
180          if edge.triangles[0].is_some() && edge.triangles[1].is_none() {
181            if edge.vertices[0] == *index {
182              vertex.adjacent_vertices.remove (&edge.vertices[1]);
183              vertex.adjacent_edges.remove (&edge_key);
184            } else if edge.vertices[1] == *index {
185              vertex.adjacent_vertices.remove (&edge.vertices[0]);
186              vertex.adjacent_edges.remove (&edge_key);
187            }
188          }
189        }
190        vertex.adjacent_triangles.remove (&triangle_key);
191        if vertex.adjacent_triangles.is_empty() {
192          self.vertices.remove (index);
193        }
194      }
195      self.et_mesh.remove (v0, v1, v2)
196    } else {
197      false
198    }
199  }
200
201  // TODO: more methods
202}
203
204impl std::ops::Deref for VertexEdgeTriangleMesh {
205  type Target = EdgeTriangleMesh;
206  fn deref (&self) -> &EdgeTriangleMesh {
207    &self.et_mesh
208  }
209}
210
211impl Vertex {
212  pub fn new (index : u32) -> Self {
213    Self {
214      index,
215      adjacent_vertices:  BTreeSet::new(),
216      adjacent_edges:     BTreeSet::new(),
217      adjacent_triangles: BTreeSet::new()
218    }
219  }
220  pub fn index (&self) -> u32 {
221    self.index
222  }
223  pub fn adjacent_vertices (&self) -> &BTreeSet <u32> {
224    &self.adjacent_vertices
225  }
226  pub fn adjacent_edges (&self) -> &BTreeSet <EdgeKey> {
227    &self.adjacent_edges
228  }
229  pub fn adjacent_triangles (&self) -> &BTreeSet <TriangleKey> {
230    &self.adjacent_triangles
231  }
232}
233
234impl Edge {
235  pub fn new (v0 : u32, v1 : u32) -> Self {
236    Edge {
237      vertices:  [v0, v1],
238      triangles: [None, None],
239    }
240  }
241  #[inline]
242  pub fn vertices (&self) -> &[u32; 2] {
243    &self.vertices
244  }
245  #[inline]
246  pub fn triangles (&self) -> &[Option <TriangleKey>; 2] {
247    &self.triangles
248  }
249}
250
251impl Triangle {
252  pub fn new (v0 : u32, v1 : u32, v2 : u32) -> Self {
253    Triangle {
254      vertices:           [v0, v1, v2],
255      edges:              [None, None, None],
256      adjacent_triangles: [None, None, None]
257    }
258  }
259
260  #[inline]
261  pub fn vertices (&self) -> &[u32; 3] {
262    &self.vertices
263  }
264  #[inline]
265  pub fn edges (&self) -> &[Option <EdgeKey>; 3] {
266    &self.edges
267  }
268  #[inline]
269  pub fn adjacent_triangles (&self) -> &[Option <TriangleKey>; 3] {
270    &self.adjacent_triangles
271  }
272}
273
274impl EdgeKey {
275  pub fn new (a : u32, b : u32) -> Self {
276    if a < b {
277      EdgeKey (a, b)
278    } else {
279      EdgeKey (b, a)
280    }
281  }
282}
math_utils/geometry/mesh/edge_triangle.rs

math_utils/geometry/mesh/
edge_triangle.rs
