Add comment about new_colset

tomneep · tomneep · commit f31f2058ddc7 · 2021-07-26T10:50:00.000+01:00
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -1658,6 +1658,9 @@ def plot_surface(self, X, Y, Z, *args, norm=None, vmin=None,
             new_polys = []
             new_colset = []
 
+            # Depending on fcolors, colset is either an empty list or has as
+            # many elements as polys. In the former case new_colset results in
+            # a list with None entries, that is discarded later.
             for p, col in itertools.zip_longest(polys, colset):
                 new_poly = np.array(p)[~np.isnan(p).any(axis=1)]
                 if len(new_poly):
