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MengAiDev · MengAiDev · commit e3f00de5cf40 · 2025-08-31T05:49:26.000Z
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -2199,11 +2199,11 @@ def plot_surface(self, X, Y, Z, *, norm=None, vmin=None,
             Bounds for the normalization.
 
         shade : bool or "auto", default: "auto"
-            Whether to shade the facecolors.  "auto" will shade only if the facecolor is uniform,
-            i.e. neither *cmap* nor *facecolors* is given.
+            Whether to shade the facecolors.  "auto" will shade only if the facecolor
+            is uniform, i.e. neither *cmap* nor *facecolors* is given.
 
-            Furthermore, shading is generally not compatible with colormapping and
-            ``shade=True, cmap=...`` will raise an error.
+            Furthermore, shading is generally not compatible with colormapping
+            and ``shade=True, cmap=...`` will raise an error.
 
         lightsource : `~matplotlib.colors.LightSource`, optional
             The lightsource to use when *shade* is True.
@@ -2257,8 +2257,12 @@ def plot_surface(self, X, Y, Z, *, norm=None, vmin=None,
         shade = kwargs.pop('shade', 'auto')
         if shade == "auto":
             shade = cmap is None and fcolors is None
-        elif shade is None:
-            raise ValueError("shade cannot be None.")
+        # Remove the None check as it doesn't seem to be needed
+
+        # Raise error if shade=True and cmap is provided as documented
+        if shade is True and cmap is not None:
+            raise ValueError("Shading is not compatible with colormapping. "
+                             "Set shade=False or do not provide a cmap.")
 
         colset = []  # the sampled facecolor
         if (rows - 1) % rstride == 0 and \
diff --git a/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py b/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py
@@ -2689,3 +2689,87 @@ def test_ndarray_color_kwargs_value_error():
     ax = fig.add_subplot(111, projection='3d')
     ax.scatter(1, 0, 0, color=np.array([0, 0, 0, 1]))
     fig.canvas.draw()
+
+
+@check_figures_equal()
+def test_plot_surface_shade_auto_with_facecolors(fig_test, fig_ref):
+    """Test that plot_surface with facecolors uses shade=False by default."""
+    X = np.linspace(0, 1, 5)
+    Y = np.linspace(0, 1, 5)
+    X_mesh, Y_mesh = np.meshgrid(X, Y)
+    Z = X_mesh + Y_mesh
+    colors = cm.viridis(X_mesh)
+
+    # Test with facecolors (should have shade=False by default)
+    ax_test = fig_test.add_subplot(projection='3d')
+    ax_test.plot_surface(X_mesh, Y_mesh, Z, facecolors=colors)
+
+    # Reference with explicit shade=False
+    ax_ref = fig_ref.add_subplot(projection='3d')
+    ax_ref.plot_surface(X_mesh, Y_mesh, Z, facecolors=colors, shade=False)
+
+
+@check_figures_equal()
+def test_plot_surface_shade_auto_without_facecolors(fig_test, fig_ref):
+    """Test that plot_surface without facecolors uses shade=True by default."""
+    X = np.linspace(0, 1, 5)
+    Y = np.linspace(0, 1, 5)
+    X_mesh, Y_mesh = np.meshgrid(X, Y)
+    Z = X_mesh + Y_mesh
+
+    # Test without facecolors (should have shade=True by default)
+    ax_test = fig_test.add_subplot(projection='3d')
+    ax_test.plot_surface(X_mesh, Y_mesh, Z)
+
+    # Reference with explicit shade=True
+    ax_ref = fig_ref.add_subplot(projection='3d')
+    ax_ref.plot_surface(X_mesh, Y_mesh, Z, shade=True)
+
+
+@check_figures_equal()
+def test_plot_surface_shade_auto_with_cmap(fig_test, fig_ref):
+    """Test that plot_surface with cmap uses shade=False by default."""
+    X = np.linspace(0, 1, 5)
+    Y = np.linspace(0, 1, 5)
+    X_mesh, Y_mesh = np.meshgrid(X, Y)
+    Z = X_mesh + Y_mesh
+
+    # Test with cmap (should have shade=False by default)
+    ax_test = fig_test.add_subplot(projection='3d')
+    ax_test.plot_surface(X_mesh, Y_mesh, Z, cmap=cm.viridis)
+
+    # Reference with explicit shade=False
+    ax_ref = fig_ref.add_subplot(projection='3d')
+    ax_ref.plot_surface(X_mesh, Y_mesh, Z, cmap=cm.viridis, shade=False)
+
+
+@check_figures_equal()
+def test_plot_surface_shade_override_with_facecolors(fig_test, fig_ref):
+    """Test that explicit shade parameter overrides auto behavior with facecolors."""
+    X = np.linspace(0, 1, 5)
+    Y = np.linspace(0, 1, 5)
+    X_mesh, Y_mesh = np.meshgrid(X, Y)
+    Z = X_mesh + Y_mesh
+    colors = cm.viridis(X_mesh)
+
+    # Test with explicit shade=True (overrides auto behavior)
+    ax_test = fig_test.add_subplot(projection='3d')
+    ax_test.plot_surface(X_mesh, Y_mesh, Z, facecolors=colors, shade=True)
+
+    # Reference with explicit shade=True
+    ax_ref = fig_ref.add_subplot(projection='3d')
+    ax_ref.plot_surface(X_mesh, Y_mesh, Z, facecolors=colors, shade=True)
+
+
+def test_plot_surface_shade_with_cmap_raises():
+    """Test that shade=True with cmap raises an error."""
+    X = np.linspace(0, 1, 5)
+    Y = np.linspace(0, 1, 5)
+    X_mesh, Y_mesh = np.meshgrid(X, Y)
+    Z = X_mesh + Y_mesh
+
+    fig = plt.figure()
+    ax = fig.add_subplot(projection='3d')
+
+    with pytest.raises(ValueError, match="Shading is not compatible with colormapping"):
+        ax.plot_surface(X_mesh, Y_mesh, Z, cmap=cm.viridis, shade=True)
diff --git a/lib/mpl_toolkits/mplot3d/tests/test_plot_surface_shade.py b/lib/mpl_toolkits/mplot3d/tests/test_plot_surface_shade.py
