Implement getting neighbors list from Delaunay, IntDelaunay, RawIntTriangulation

Author: mikwielgus

iTriangle/src/advanced/triangulation.rs

@@ -4,11 +4,13 @@ use alloc::vec::Vec;
 use i_overlay::i_float::int::point::IntPoint;
 
 impl IntDelaunay {
+    /// Returns the vertex positions in the triangulation.
     #[inline]
     pub fn points(&self) -> &Vec<IntPoint> {
         &self.points
     }
 
+    /// Returns indices forming counter-clockwise triangles.
     #[inline]
     pub fn triangle_indices<I: IndexType>(&self) -> Vec<I> {
         let mut result = Vec::with_capacity(3 * self.triangles.len());
@@ -23,6 +25,15 @@ impl IntDelaunay {
         result
     }
 
+    /// Returns the indices of each triangle's neighboring triangles.
+    #[inline]
+    pub fn triangle_neighbors(&self) -> Vec<[usize; 3]> {
+        self.triangles
+            .iter()
+            .map(|triangle| triangle.neighbors)
+            .collect()
+    }
+
     #[inline]
     pub fn into_triangulation<I: IndexType>(self) -> IntTriangulation<I> {
         IntTriangulation {

iTriangle/src/float/delaunay.rs

@@ -45,6 +45,12 @@ impl<P: FloatPointCompatible> Delaunay<P> {
         self.delaunay.triangle_indices()
     }
 
+    /// Returns the indices of each triangle's neighboring triangles.
+    #[inline]
+    pub fn triangle_neighbors(&self) -> Vec<[usize; 3]> {
+        self.delaunay.triangle_neighbors()
+    }
+
     /// Converts this refined mesh into a flat float [`Triangulation`].
     #[inline]
     pub fn to_triangulation<I: IndexType>(&self) -> Triangulation<P, I> {

iTriangle/src/int/triangulation.rs

@@ -154,14 +154,22 @@ impl RawIntTriangulation {
     /// Returns a flat list of triangle vertex indices (ABC ordering).
     ///
     /// Each triangle contributes 3 indices into the `points` buffer.
-    ///
     #[inline]
     pub fn triangle_indices<I: IndexType>(&self) -> Vec<I> {
         let mut indices = Vec::new();
         self.triangles.feed_indices(self.points.len(), &mut indices);
         indices
     }
 
+    /// Returns the indices of each triangle's neighboring triangles.
+    #[inline]
+    pub fn triangle_neighbors(&self) -> Vec<[usize; 3]> {
+        self.triangles
+            .iter()
+            .map(|triangle| triangle.neighbors)
+            .collect()
+    }
+
     /// Converts the int triangulation into a simpler index-based mesh.
     ///
     /// Returns a [`IntTriangulation`] with separate index buffer and point list.