add boundary faces option to mesh_dual

add boundary faces option to mesh_dual

remove problem import

Author: GeneKao

AUTHORS.md

@@ -32,3 +32,4 @@
 - Mattis Koh <<[email protected]>> [@mattiskoh](https://github.com/mattiskoh)
 - Andrea Ghensi <<[email protected]>> [@sanzoghenzo](https://github.com/sanzoghenzo)
 - Nizar Taha <<[email protected]>> [@nizartaha](https://github.com/nizartaha)
+- Gene Ting-Chun Kao <<[email protected]>> [@GeneKao](https://github.com/GeneKao)

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Added `Data.guid` to JSON serialization.
 * Added `Data.guid` to pickle state.
 * Added `Assembly.find_by_key` to locate parts by key.
+* Added `Mesh.mesh_dual` with additional option to include boundary faces. 
 
 ### Changed
 

src/compas/datastructures/mesh/duality.py

@@ -3,15 +3,16 @@
 from __future__ import division
 
 from math import pi
-
+from compas.utilities import flatten
+from compas.utilities import geometric_key
 
 __all__ = ['mesh_dual']
 
 
 PI2 = 2.0 * pi
 
 
-def mesh_dual(mesh, cls=None):
+def mesh_dual(mesh, cls=None, boundary=0):
     """Construct the dual of a mesh.
 
     Parameters
@@ -21,6 +22,9 @@ def mesh_dual(mesh, cls=None):
     cls : Type[:class:`~compas.datastructures.Mesh`], optional
         The type of the dual mesh.
         Defaults to the type of the provided mesh object.
+    boundary: float, optional
+        boundary mode for the dual mesh
+        Default mode is 0, not create faces on boundaries
 
     Returns
     -------
@@ -34,17 +38,45 @@ def mesh_dual(mesh, cls=None):
     dual = cls()
 
     face_centroid = {face: mesh.face_centroid(face) for face in mesh.faces()}
-    inner = list(set(mesh.vertices()) - set(mesh.vertices_on_boundary()))
+    outer = list(flatten(mesh.vertices_on_boundaries()))
     vertex_xyz = {}
     face_vertices = {}
+    boundary_xyz = {}
 
-    for vertex in inner:
+    # safe guarded if face index is arbitrary, random, not starting from 0
+    num_faces = max(max(list(mesh.faces())) + 1, mesh.number_of_faces())
+    for vertex in mesh.vertices():
         faces = mesh.vertex_faces(vertex, ordered=True)
         for face in faces:
             if face not in vertex_xyz:
                 vertex_xyz[face] = face_centroid[face]
         face_vertices[vertex] = faces
 
+        if not boundary:
+            continue
+        if vertex not in outer or len(faces) <= 1:
+            continue
+
+        nbr_vertices = reversed(mesh.vertex_neighbors(vertex, ordered=True))
+        boundary_vertices = faces
+
+        for nbr_vertex in nbr_vertices:
+
+            if mesh.is_edge_on_boundary(vertex, nbr_vertex):
+                pt = mesh.edge_midpoint(vertex, nbr_vertex)
+
+                if geometric_key(pt) not in boundary_xyz and num_faces not in vertex_xyz:
+                    vertex_xyz[num_faces] = pt
+                    boundary_xyz[geometric_key(pt)] = num_faces
+                    num_faces += 1
+
+                if geometric_key(pt) in boundary_xyz:
+                    boundary_vertices.append(boundary_xyz[geometric_key(pt)])
+                else:
+                    boundary_vertices.append(num_faces)
+
+        face_vertices[vertex] = boundary_vertices
+
     for vertex in vertex_xyz:
         x, y, z = vertex_xyz[vertex]
         dual.add_vertex(vertex, x=x, y=y, z=z)