Merge pull request #1038 from GeneKao/feature/dualmesh_boundary

add boundary faces option to mesh_dual

Author: tomvanmele

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

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Fixed bug in `compas.robots.Configuration`.
 * Rebuild part index after deserialization in `Assembly`.
 * Fixed bug in `compas.artists.colordict.ColorDict`.
+* Change `Mesh.mesh_dual` with option of including the boundary. 
 
 ### Removed
 

src/compas/datastructures/mesh/duality.py

@@ -3,15 +3,15 @@
 from __future__ import division
 
 from math import pi
-
+from compas.utilities import flatten
 
 __all__ = ['mesh_dual']
 
 
 PI2 = 2.0 * pi
 
 
-def mesh_dual(mesh, cls=None):
+def mesh_dual(mesh, cls=None, include_boundary=False):
     """Construct the dual of a mesh.
 
     Parameters
@@ -21,20 +21,36 @@ 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.
+    include_boundary: bool, optional
+        Whether to include boundary faces for the dual mesh
+        If True, create faces on boundaries including all original mesh boundary vertices.
 
     Returns
     -------
     :class:`~compas.datastructures.Mesh`
         The dual mesh object.
 
+    Examples
+    --------
+    >>> import compas
+    >>> from compas.datastructures import Mesh
+    >>> mesh = Mesh.from_obj(compas.get('faces.obj'))
+    >>> mesh.delete_face(11)
+    >>> mesh.delete_face(6)
+    >>> mesh.delete_face(7)
+    >>> mesh.quads_to_triangles()
+    >>> mesh = mesh.subdivide('corner')
+    >>> dual = mesh.dual(include_boundary=True)
+
     """
     if not cls:
         cls = type(mesh)
 
     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 = set(flatten(mesh.vertices_on_boundaries()))
+    inner = list(set(mesh.vertices()) - outer)
     vertex_xyz = {}
     face_vertices = {}
 
@@ -52,4 +68,39 @@ def mesh_dual(mesh, cls=None):
     for face in face_vertices:
         dual.add_face(face_vertices[face], fkey=face)
 
+    if not include_boundary:
+        return dual
+
+    for boundary in mesh.faces_on_boundaries():
+        for face in boundary:
+            if not dual.has_vertex(face):
+                x, y, z = face_centroid[face]
+                dual.add_vertex(key=face, x=x, y=y, z=z)
+
+    edge_vertex = {}
+    for boundary in mesh.edges_on_boundaries():
+        for u, v in boundary:
+            x, y, z = mesh.edge_midpoint(u, v)
+            edge_vertex[u, v] = edge_vertex[v, u] = dual.add_vertex(x=x, y=y, z=z)
+
+    vertex_vertex = {}
+    for boundary in mesh.vertices_on_boundaries():
+        if boundary[0] == boundary[-1]:
+            boundary = boundary[:-1]
+        for vertex in boundary:
+            x, y, z = mesh.vertex_coordinates(vertex)
+            vertex_vertex[vertex] = dual.add_vertex(x=x, y=y, z=z)
+
+    for boundary in mesh.vertices_on_boundaries():
+        if boundary[0] == boundary[-1]:
+            boundary = boundary[:-1]
+        for vertex in boundary:
+            vertices = [vertex_vertex[vertex]]
+            nbrs = mesh.vertex_neighbors(vertex, ordered=True)[::-1]
+            vertices.append(edge_vertex[vertex, nbrs[0]])
+            for nbr in nbrs[:-1]:
+                vertices.append(mesh.halfedge_face(vertex, nbr))
+            vertices.append(edge_vertex[vertex, nbrs[-1]])
+            dual.add_face(vertices[::-1])
+
     return dual