matplotlib · tacaswell · Sep 24, 2020 · Feb 9, 2015 · Sep 16, 2020 · Sep 17, 2020
diff --git a/doc/users/next_whats_new/mplot3d_modification.rst b/doc/users/next_whats_new/mplot3d_modification.rst
@@ -0,0 +1,8 @@
+3D Collection properties are now modifiable
+-------------------------------------------
+
+Previously, properties of a 3D Collection that were used for 3D effects (e.g.,
+colors were modified to produce depth shading) could not be changed after it
+was created.
+
+Now it is possible to modify all properties of 3D Collections at any time.
diff --git a/lib/mpl_toolkits/mplot3d/art3d.py b/lib/mpl_toolkits/mplot3d/art3d.py
@@ -403,6 +403,32 @@ def __init__(self, *args, zs=0, zdir='z', depthshade=True, **kwargs):
         super().__init__(*args, **kwargs)
         self.set_3d_properties(zs, zdir)
 
+    def get_depthshade(self):
+        return self._depthshade
+
+    def set_depthshade(self, depthshade):
+        """
+        Set whether depth shading is performed on collection members.
+
+        Parameters
+        ----------
+        depthshade : bool
+            Whether to shade the patches in order to give the appearance of
+            depth.
+        """
+        self._depthshade = depthshade
+        self.stale = True
+
+    def set_facecolor(self, c):
+        # docstring inherited
+        super().set_facecolor(c)
+        self._facecolor3d = self.get_facecolor()
+
+    def set_edgecolor(self, c):
+        # docstring inherited
+        super().set_edgecolor(c)
+        self._edgecolor3d = self.get_edgecolor()
+
     def set_sort_zpos(self, val):
         """Set the position to use for z-sorting."""
         self._sort_zpos = val
@@ -430,13 +456,13 @@ def do_3d_projection(self, renderer):
         fcs = (_zalpha(self._facecolor3d, vzs) if self._depthshade else
                self._facecolor3d)
         fcs = mcolors.to_rgba_array(fcs, self._alpha)
-        self.set_facecolors(fcs)
+        super().set_facecolor(fcs)
 
         ecs = (_zalpha(self._edgecolor3d, vzs) if self._depthshade else
                self._edgecolor3d)
         ecs = mcolors.to_rgba_array(ecs, self._alpha)
-        self.set_edgecolors(ecs)
-        PatchCollection.set_offsets(self, np.column_stack([vxs, vys]))
+        super().set_edgecolor(ecs)
+        super().set_offsets(np.column_stack([vxs, vys]))
 
         if vzs.size > 0:
             return min(vzs)
@@ -491,6 +517,42 @@ def set_3d_properties(self, zs, zdir):
         self._linewidth3d = self.get_linewidth()
         self.stale = True
 
+    def get_depthshade(self):
+        return self._depthshade
+
+    def set_depthshade(self, depthshade):
+        """
+        Set whether depth shading is performed on collection members.
+
+        Parameters
+        ----------
+        depthshade : bool
+            Whether to shade the patches in order to give the appearance of
+            depth.
+        """
+        self._depthshade = depthshade
+        self.stale = True
+
+    def set_facecolor(self, c):
+        # docstring inherited
+        super().set_facecolor(c)
+        self._facecolor3d = self.get_facecolor()
+
+    def set_edgecolor(self, c):
+        # docstring inherited
+        super().set_edgecolor(c)
+        self._edgecolor3d = self.get_edgecolor()
+
+    def set_sizes(self, sizes, dpi=72.0):
+        # docstring inherited
+        super().set_sizes(sizes, dpi=dpi)
+        self._sizes3d = self.get_sizes()
+
+    def set_linewidth(self, lw):
+        # docstring inherited
+        super().set_linewidth(lw)
+        self._linewidth3d = self.get_linewidth()
+
     def do_3d_projection(self, renderer):
         xs, ys, zs = self._offsets3d
         vxs, vys, vzs, vis = proj3d.proj_transform_clip(xs, ys, zs, renderer.M)
@@ -524,10 +586,10 @@ def do_3d_projection(self, renderer):
         fcs = mcolors.to_rgba_array(fcs, self._alpha)
         ecs = mcolors.to_rgba_array(ecs, self._alpha)
 
-        self.set_edgecolors(ecs)
-        self.set_facecolors(fcs)
-        self.set_sizes(sizes)
-        self.set_linewidth(lws)
+        super().set_edgecolor(ecs)
+        super().set_facecolor(fcs)
+        super().set_sizes(sizes)
+        super().set_linewidth(lws)
 
         PathCollection.set_offsets(self, vps)
 
@@ -722,10 +784,12 @@ def do_3d_projection(self, renderer):
             return np.nan
 
     def set_facecolor(self, colors):
+        # docstring inherited
         super().set_facecolor(colors)
         self._facecolors3d = PolyCollection.get_facecolor(self)
 
     def set_edgecolor(self, colors):
+        # docstring inherited
         super().set_edgecolor(colors)
         self._edgecolors3d = PolyCollection.get_edgecolor(self)
 

diff --git a/lib/mpl_toolkits/tests/test_mplot3d.py b/lib/mpl_toolkits/tests/test_mplot3d.py
@@ -243,6 +243,27 @@ def test_scatter3d_color():
                color='b', marker='s')
 
 
+@check_figures_equal(extensions=['png'])
+def test_scatter3d_modification(fig_ref, fig_test):
+    # Changing Path3DCollection properties post-creation should work correctly.
+    ax_test = fig_test.add_subplot(projection='3d')
+    c = ax_test.scatter(np.arange(10), np.arange(10), np.arange(10),
+                        marker='o')
+    c.set_facecolor('C1')
+    c.set_edgecolor('C2')
+    c.set_alpha([0.3, 0.7] * 5)
+    assert c.get_depthshade()
+    c.set_depthshade(False)
+    assert not c.get_depthshade()
+    c.set_sizes(np.full(10, 75))
+    c.set_linewidths(3)
+
+    ax_ref = fig_ref.add_subplot(projection='3d')
+    ax_ref.scatter(np.arange(10), np.arange(10), np.arange(10), marker='o',
+                   facecolor='C1', edgecolor='C2', alpha=[0.3, 0.7] * 5,
+                   depthshade=False, s=75, linewidths=3)
+
+
 @pytest.mark.parametrize('depthshade', [True, False])
 @check_figures_equal(extensions=['png'])
 def test_scatter3d_sorting(fig_ref, fig_test, depthshade):
@@ -526,6 +547,30 @@ def test_quiver3d_masked():
     ax.quiver(x, y, z, u, v, w, length=0.1, pivot='tip', normalize=True)
 
 
+@check_figures_equal(extensions=['png'])
+def test_patch_collection_modification(fig_test, fig_ref):
+    # Test that modifying Patch3DCollection properties after creation works.
+    patch = Circle((0, 0), 0.05)
+    c = art3d.Patch3DCollection([patch], linewidths=3)
+
+    ax_test = fig_test.add_subplot(projection='3d')
+    ax_test.add_collection3d(c)
+    c.set_edgecolor('C2')
+    c.set_facecolor('C3')
+    c.set_alpha(0.7)
+    assert c.get_depthshade()
+    c.set_depthshade(False)
+    assert not c.get_depthshade()
+
+    patch = Circle((0, 0), 0.05)
+    c = art3d.Patch3DCollection([patch], linewidths=3,
+                                edgecolor='C2', facecolor='C3', alpha=0.7,
+                                depthshade=False)
+
+    ax_ref = fig_ref.add_subplot(projection='3d')
+    ax_ref.add_collection3d(c)
+
+
 @mpl3d_image_comparison(['poly3dcollection_closed.png'])
 def test_poly3dcollection_closed():
     fig = plt.figure()
@@ -558,8 +603,10 @@ def test_poly3dcollection_alpha():
     c1 = art3d.Poly3DCollection([poly1], linewidths=3, edgecolor='k',
                                 facecolor=(0.5, 0.5, 1), closed=True)
     c1.set_alpha(0.5)
-    c2 = art3d.Poly3DCollection([poly2], linewidths=3, edgecolor='k',
-                                facecolor=(1, 0.5, 0.5), closed=False)
+    c2 = art3d.Poly3DCollection([poly2], linewidths=3, closed=False)
+    # Post-creation modification should work.
+    c2.set_facecolor((1, 0.5, 0.5))
+    c2.set_edgecolor('k')
     c2.set_alpha(0.5)
     ax.add_collection3d(c1)
     ax.add_collection3d(c2)