Merge pull request #803 from compas-dev/thickening-direction

Update offset module

Author: tomvanmele

CHANGELOG.md

@@ -10,9 +10,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* Added Python 3.9 support.
 * Added crease handling to catmull-clark subdivision scheme.
-* Added Python 3.9 support
 * Added `compas_ghpython.get_grasshopper_userobjects_path` to retrieve User Objects target folder.
+* Added direction option for mesh thickening.
+* Added check for closed meshes.
 
 ### Changed
 

src/compas/datastructures/mesh/core/halfedge.py

@@ -1739,17 +1739,34 @@ def is_quadmesh(self):
         return not any(4 != len(self.face_vertices(fkey)) for fkey in self.faces())
 
     def is_empty(self):
-        """Boolean whether the mesh is empty.
+        """Verify that the mesh is empty.
 
         Returns
         -------
         bool
-            True if no vertices. False otherwise.
+            True if the mesh has no vertices.
+            False otherwise.
         """
         if self.number_of_vertices() == 0:
             return True
         return False
 
+    def is_closed(self):
+        """Verify that the mesh is closed.
+
+        Returns
+        -------
+        bool
+            True if the mesh is not empty and has no naked edges.
+            False otherwise.
+        """
+        if self.is_empty():
+            return False
+        for edge in self.edges():
+            if self.is_edge_on_boundary(*edge):
+                return False
+        return True
+
     def euler(self):
         """Calculate the Euler characteristic.
 

src/compas/datastructures/mesh/offset.py

@@ -14,51 +14,96 @@
 ]
 
 
-def mesh_offset(mesh, distance=1.0,):
+def mesh_offset(mesh, distance=1.0):
     """Offset a mesh.
 
     Parameters
     ----------
-    mesh : Mesh
+    mesh : :class:`compas.datastructures.Mesh`
         A Mesh to offset.
-    distance : float
+    distance : float, optional
         The offset distance.
+        Default is ``1.0``.
 
     Returns
     -------
-    Mesh
+    :class:`compas.datastructures.Mesh`
         The offset mesh.
 
+    Notes
+    -----
+    If the offset distance is a positive value, the offset is in the direction of the vertex normal.
+    If the value is negative, the offset is in the opposite direction.
+    In both cases, the orientation of the offset mesh is the same as the orientation of the original.
+
+    In areas with high degree of curvature, the offset mesh can have self-intersections.
+
+    Examples
+    --------
+    >>> from compas.datastructures import Mesh, mesh_offset
+    >>> from compas.geometry import distance_point_point as dist
+    >>> mesh = Mesh.from_vertices_and_faces([[0, 0, 0], [1, 0, 0], [1, 1, 0], [0, 1, 0]], [[0, 1, 2, 3]])
+    >>> offset = mesh_offset(mesh)
+    >>> all(dist(mesh.vertex_coordinates(a), offset.vertex_coordinates(b)) == 1 for a, b in zip(mesh.vertices(), offset.vertices()))
+    True
+
     """
     offset = mesh.copy()
 
-    for key in offset.vertices():
-        normal = mesh.vertex_normal(key)
-        xyz = mesh.vertex_coordinates(key)
-        offset.vertex_attributes(key, 'xyz', add_vectors(xyz, scale_vector(normal, distance)))
+    for vertex in offset.vertices():
+        normal = mesh.vertex_normal(vertex)
+        xyz = mesh.vertex_coordinates(vertex)
+        offset.vertex_attributes(vertex, 'xyz', add_vectors(xyz, scale_vector(normal, distance)))
 
     return offset
 
 
-def mesh_thicken(mesh, thickness=1.0):
+def mesh_thicken(mesh, thickness=1.0, both=True):
     """Thicken a mesh.
 
     Parameters
     ----------
-    mesh : Mesh
+    mesh : :class:`compas.datastructures.Mesh`
         A mesh to thicken.
-    thickness : real
-        The mesh thickness
+    thickness : float, optional
+        The mesh thickness.
+        This should be a positive value.
+        Default is ``1.0``.
+    both : bool, optional
+        If true, the mesh is thickened on both sides of the original.
+        Otherwise, the mesh is thickened on the side of the positive normal.
 
     Returns
     -------
-    thickened_mesh : Mesh
+    thickened_mesh : :class:`compas.datastructures.Mesh`
         The thickened mesh.
 
+    Raises
+    ------
+    ValueError
+        If ``thickness`` is not a positive number.
+
+    Examples
+    --------
+    >>> from compas.datastructures import Mesh, mesh_thicken
+    >>> from compas.geometry import distance_point_point as dist
+    >>> mesh = Mesh.from_vertices_and_faces([[0, 0, 0], [1, 0, 0], [1, 1, 0], [0, 1, 0]], [[0, 1, 2, 3]])
+    >>> thick = mesh_thicken(mesh)
+    >>> thick.is_closed()
+    True
+    >>> all(dist(mesh.vertex_coordinates(a), thick.vertex_coordinates(b)) == 1 for a, b in zip(mesh.vertices(), thick.vertices()))
+    True
+
     """
-    # offset in both directions
-    mesh_top = mesh_offset(mesh, +0.5 * thickness)
-    mesh_bottom = mesh_offset(mesh, -0.5 * thickness)
+    if thickness <= 0:
+        raise ValueError("Thickness should be a positive number.")
+
+    if both:
+        mesh_top = mesh_offset(mesh, +0.5 * thickness)
+        mesh_bottom = mesh_offset(mesh, -0.5 * thickness)
+    else:
+        mesh_top = mesh_offset(mesh, thickness)
+        mesh_bottom = mesh.copy()
 
     # flip bottom part
     mesh_flip_cycles(mesh_bottom)
@@ -85,4 +130,4 @@ def mesh_thicken(mesh, thickness=1.0):
 if __name__ == '__main__':
 
     import doctest
-    doctest.testmod(globs=globals())
+    doctest.testmod()