Merge pull request #1084 from compas-dev/fix-halfedge-before-on-boundary

Fix bug in Mesh.halfedge_before

Author: tomvanmele

CHANGELOG.md

@@ -36,6 +36,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Fixed bug in `_core.tangent` where the Circle's Plane was accessed instead of the centre.
 * Fixed the `test_tangent` to work with a properly defined circle
 * `RhinoBrep` serialization works now with surface types other than NURBS.
+* Fixed bug in finding halfedge before a given halfedge if that halfedge is on the boundary (`Mesh.halfedge_before`).
 
 ### Removed
 

src/compas/datastructures/halfedge/halfedge.py

@@ -2607,7 +2607,7 @@ def halfedge_after(self, u, v):
         if face is not None:
             w = self.face_vertex_after(face, v)
             return v, w
-        nbrs = self.vertex_neighbors(u, ordered=True)
+        nbrs = self.vertex_neighbors(v, ordered=True)
         w = nbrs[0]
         return v, w
 

tests/compas/datastructures/test_halfedge.py

@@ -269,6 +269,33 @@ def test_del_edge_attribute_in_view(mesh, edge_key):
         attrs["foo"]
 
 
+# ==============================================================================
+# Tests - Halfedges Before/After
+# ==============================================================================
+
+
+def test_halfedge_after_on_boundary(grid):
+    corners = list(grid.vertices_where(vertex_degree=2))
+    corner = corners[0]
+    nbrs = grid.vertex_neighbors(corner, ordered=True)
+    nbr = nbrs[-1]
+    edge = grid.halfedge_after(nbr, corner)
+    assert edge[0] == corner
+    assert grid.is_edge_on_boundary(*edge)
+    assert grid.halfedge_face(*edge) is None
+
+
+def test_halfedge_before_on_boundary(grid):
+    corners = list(grid.vertices_where(vertex_degree=2))
+    corner = corners[0]
+    nbrs = grid.vertex_neighbors(corner, ordered=True)
+    nbr = nbrs[0]
+    edge = grid.halfedge_before(corner, nbr)
+    assert edge[1] == corner
+    assert grid.is_edge_on_boundary(*edge)
+    assert grid.halfedge_face(*edge) is None
+
+
 # ==============================================================================
 # Tests - Loops & Strip
 # ==============================================================================