Merge pull request #2077 from hannobraun/sibling

Add query API for half-edge siblings

crates/fj-core/src/objects/kinds/shell.rs

@@ -1,6 +1,5 @@
 use crate::{
-    objects::{handles::Handles, Face, HalfEdge},
+    objects::{handles::Handles, Face},
-    queries::BoundingVerticesOfHalfEdge,
     storage::Handle,
 };
 
@@ -22,28 +21,4 @@ impl Shell {
     pub fn faces(&self) -> &Handles<Face> {
         &self.faces
     }
-
-    /// Indicate whether the provided half-edges are siblings
-    pub 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
-    }
 }

crates/fj-core/src/queries/mod.rs

@@ -11,8 +11,10 @@
 
 mod all_half_edges_with_surface;
 mod bounding_vertices_of_half_edge;
+mod sibling_of_half_edge;
 
 pub use self::{
     all_half_edges_with_surface::AllHalfEdgesWithSurface,
     bounding_vertices_of_half_edge::BoundingVerticesOfHalfEdge,
+    sibling_of_half_edge::SiblingOfHalfEdge,
 };

crates/fj-core/src/queries/sibling_of_half_edge.rs

@@ -0,0 +1,60 @@
+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
+    }
+}

crates/fj-core/src/validate/shell.rs

@@ -5,7 +5,9 @@ use fj_math::{Point, Scalar};
 use crate::{
     geometry::SurfaceGeometry,
     objects::{HalfEdge, Shell, Surface},
-    queries::{AllHalfEdgesWithSurface, BoundingVerticesOfHalfEdge},
+    queries::{
+        AllHalfEdgesWithSurface, BoundingVerticesOfHalfEdge, SiblingOfHalfEdge,
+    },
     storage::{Handle, HandleWrapper},
 };