Code review changes

scottshambaugh · scottshambaugh · commit f8c555054fa3 · 2022-01-05T08:21:09.000-07:00
diff --git a/doc/users/next_whats_new/3d_plot_focal_length.rst b/doc/users/next_whats_new/3d_plot_focal_length.rst
@@ -3,13 +3,16 @@ Give the 3D camera a custom focal length
 
 Users can now better mimic real-world cameras by specifying the focal length of
 the virtual camera in 3D plots. An increasing focal length between 1 and
-+infinity "flattens" the image, while a decreasing focal length between 1 and 0
+infinity "flattens" the image, while a decreasing focal length between 1 and 0
 exaggerates the perspective and gives the image more apparent depth. The
 default focal length of 1 corresponds to a Field of View (FOV) of 90 deg, and
 is backwards-compatible with existing 3D plots.
 
 The focal length can be calculated from a desired FOV via the equation:
-| ``focal_length = 1/tan(FOV/2)``
+
+.. mathmpl::
+
+    focal_length = 1/tan(FOV/2)
 
 .. plot::
     :include-source: true
diff --git a/examples/mplot3d/projections.py b/examples/mplot3d/projections.py
@@ -7,18 +7,18 @@
 changing the focal length for a perspective projection. Note that matplotlib
 corrects for the 'zoom' effect of changing the focal length.
 
-An increasing focal length between 1 and +infinity "flattens" the image, while
+An increasing focal length between 1 and infinity "flattens" the image, while
 a decreasing focal length between 1 and 0 exaggerates the perspective and gives
 the image more apparent depth. The default focal length of 1 corresponds to a
 Field of View (FOV) of 90 deg. In the limiting case, a focal length of
-+infinity corresponds to an orthographic projection after correction of the
+infinity corresponds to an orthographic projection after correction of the
 zoom effect.
 
 You can calculate focal length from a FOV via the equation:
-focal_length = 1/tan(FOV/2)
+:mathmpl:`1/tan(FOV/2)`
+
+Or vice versa: :mathmpl:`FOV = 2*atan(1/focal_length)`
 
-Or vice versa:
-FOV = 2*atan(1/focal_length)
 """
 
 from mpl_toolkits.mplot3d import axes3d
@@ -36,7 +36,7 @@
 
 # Set the orthographic projection.
 axs[0].set_proj_type('ortho')  # FOV = 0 deg
-axs[0].set_title("'ortho'\nfocal_length = +∞", fontsize=10)
+axs[0].set_title("'ortho'\nfocal_length = ∞", fontsize=10)
 
 # Set the perspective projections
 axs[1].set_proj_type('persp')  # FOV = 90 deg
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -1046,22 +1046,20 @@ def set_proj_type(self, proj_type, focal_length=None):
             The focal length can be computed from a desired Field Of View via
             the equation: focal_length = 1/tan(FOV/2)
         """
+        _api.check_in_list(['persp', 'ortho'], proj_type=proj_type)
         if proj_type == 'persp':
             if focal_length is None:
                 self.focal_length = 1
             else:
                 if focal_length <= 0:
-                    raise ValueError(f"focal_length = {focal_length} must be" +
+                    raise ValueError(f"focal_length = {focal_length} must be"
                                      " greater than 0")
                 self.focal_length = focal_length
         elif proj_type == 'ortho':
             if focal_length not in (None, np.inf):
-                raise ValueError(f"focal_length = {focal_length} must be" +
+                raise ValueError(f"focal_length = {focal_length} must be"
                                  f"None for proj_type = {proj_type}")
             self.focal_length = np.inf
-        else:
-            raise ValueError(f"proj_type = {proj_type} must be in" +
-                             f"{'persp', 'ortho'}")
 
     def _roll_to_vertical(self, arr):
         """Roll arrays to match the different vertical axis."""
