Refactor silhouette from add_mesh

pyvista/plotting/plotting.py

@@ -1875,31 +1875,11 @@ def add_mesh(self, mesh, color=None, style=None, scalars=None,
 
         ##### Plot a single PyVista mesh #####
 
-        silhouette_params = self._theme.silhouette.to_dict()
-        if isinstance(silhouette, dict):
-            silhouette_params.update(silhouette)
-            silhouette = True
         if silhouette:
-            if not isinstance(mesh, pyvista.PolyData):
-                raise TypeError(f"Expected type is `PolyData` but {type(mesh)} was given.")
-            if isinstance(silhouette_params["decimate"], float):
-                silhouette_mesh = mesh.decimate(silhouette_params["decimate"])
-            else:
-                silhouette_mesh = mesh
-            alg = _vtk.vtkPolyDataSilhouette()
-            alg.SetInputData(silhouette_mesh)
-            alg.SetCamera(self.renderer.camera)
-            if silhouette_params["feature_angle"] is not None:
-                alg.SetEnableFeatureAngle(True)
-                alg.SetFeatureAngle(silhouette_params["feature_angle"])
+            if isinstance(silhouette, dict):
+                self.add_silhouette(mesh, silhouette)
             else:
-                alg.SetEnableFeatureAngle(False)
-            mapper = make_mapper(_vtk.vtkDataSetMapper)
-            mapper.SetInputConnection(alg.GetOutputPort())
-            _, prop = self.add_actor(mapper)
-            prop.SetColor(parse_color(silhouette_params["color"]))
-            prop.SetOpacity(silhouette_params["opacity"])
-            prop.SetLineWidth(silhouette_params["line_width"])
+                self.add_silhouette(mesh)
 
         # Compute surface normals if using smooth shading
         if smooth_shading:
@@ -2694,6 +2674,73 @@ def add_volume(self, volume, scalars=None, clim=None, resolution=None,
 
         return actor
 
+    def add_silhouette(self, mesh, params=None):
+        """Add a silhouette of a PyVista/VTK mesh or dataset that PyVista can wrap to the scene.
+
+        A silhouette can also be generated directly in
+        :func:`pyvista.BasePlotter.add_mesh`.  See also :ref:`silhouette_example`.
+
+        Parameters
+        ----------
+        mesh : pyvista.PolyData
+
+        params : dict, optional
+                * If not supplied, the default theme values will be used.
+                * ``color``: ``str`` or 3-item ``list``, color of the silhouette
+                * ``line_width``: ``float``, edge width
+                * ``opacity``: ``float`` between 0 and 1, edge transparency
+                * ``feature_angle``: If a ``float``, display sharp edges
+                  exceeding that angle in degrees.
+                * ``decimate``: ``float`` between 0 and 1, level of decimation
+
+        Returns
+        -------
+        vtk.vtkActor
+            VTK actor of the silhouette.
+
+        Examples
+        --------
+        >>> import pyvista
+        >>> from pyvista import examples
+        >>> bunny = examples.download_bunny()
+        >>> plotter = pyvista.Plotter()
+        >>> _ = plotter.add_mesh(bunny, color='tan')
+        >>> _ = plotter.add_silhouette(bunny, 
+        ...     params={'color': 'red', 'line_width': 8.0})
+        >>> plotter.view_xy()
+        >>> plotter.show()
+
+        """
+        silhouette_params = self._theme.silhouette.to_dict()
+        if params:
+            silhouette_params.update(params)
+
+        if not is_pyvista_dataset(mesh):
+            mesh = wrap(mesh)
+        if not isinstance(mesh, pyvista.PolyData):
+            raise TypeError(f"Expected type is `PolyData` but {type(mesh)} was given.")
+
+        if isinstance(silhouette_params["decimate"], float):
+            silhouette_mesh = mesh.decimate(silhouette_params["decimate"])
+        else:
+            silhouette_mesh = mesh
+        alg = _vtk.vtkPolyDataSilhouette()
+        alg.SetInputData(silhouette_mesh)
+        alg.SetCamera(self.renderer.camera)
+        if silhouette_params["feature_angle"] is not None:
+            alg.SetEnableFeatureAngle(True)
+            alg.SetFeatureAngle(silhouette_params["feature_angle"])
+        else:
+            alg.SetEnableFeatureAngle(False)
+        mapper = make_mapper(_vtk.vtkDataSetMapper)
+        mapper.SetInputConnection(alg.GetOutputPort())
+        actor, prop = self.add_actor(mapper)
+        prop.SetColor(parse_color(silhouette_params["color"]))
+        prop.SetOpacity(silhouette_params["opacity"])
+        prop.SetLineWidth(silhouette_params["line_width"])
+
+        return actor
+
     def update_scalar_bar_range(self, clim, name=None):
         """Update the value range of the active or named scalar bar.
 

tests/plotting/test_plotting.py

@@ -569,6 +569,25 @@ def test_plot_silhouette(tri_cylinder):
     plotter.show(before_close_callback=verify_cache_image)
 
 
+def test_plot_silhouette_method(tri_cylinder):
+    plotter = pyvista.Plotter()
+
+    plotter.add_mesh(tri_cylinder)
+    actors = list(plotter.renderer.GetActors())
+    assert len(actors) == 1  # cylinder
+
+    plotter.add_silhouette(tri_cylinder)
+    actors = list(plotter.renderer.GetActors())
+    assert len(actors) == 2 # cylinder + silhouette
+
+    actor = actors[1]  # get silhouette actor
+    props = actor.GetProperty()
+    assert props.GetColor() == pyvista.parse_color(pyvista.global_theme.silhouette.color)
+    assert props.GetOpacity() == pyvista.global_theme.silhouette.opacity
+    assert props.GetLineWidth() == pyvista.global_theme.silhouette.line_width
+    plotter.show(before_close_callback=verify_cache_image)
+
+
 def test_plot_silhouette_options(tri_cylinder):
     # cover other properties
     plotter = pyvista.Plotter()