expose 'mode' for plotting dipole on brain (#13162)

Co-authored-by: Marijn van Vliet <w.m.vanvliet@gmail.com>

Author: sappelhoff

mne/viz/_brain/_brain.py

@@ -2338,7 +2338,9 @@ def remove_forward(self):
         self._remove("forward", render=True)
 
     @fill_doc
-    def add_dipole(self, dipole, trans, colors="red", alpha=1, scales=None):
+    def add_dipole(
+        self, dipole, trans, colors="red", alpha=1, scales=None, *, mode="arrow"
+    ):
         """Add a quiver to render positions of dipoles.
 
         Parameters
@@ -2354,6 +2356,9 @@ def add_dipole(self, dipole, trans, colors="red", alpha=1, scales=None):
         scales : list | float | None
             The size of the arrow representing the dipole in
             :class:`mne.viz.Brain` units. Default 5mm.
+        mode : "2darrow" | "arrow" | "cone" | "cylinder" | "sphere" | "oct"
+            The drawing mode for the dipole to render.
+            Defaults to ``"arrow"``.
 
         Notes
         -----
@@ -2392,7 +2397,7 @@ def add_dipole(self, dipole, trans, colors="red", alpha=1, scales=None):
                     *this_ori,
                     color=color,
                     opacity=alpha,
-                    mode="arrow",
+                    mode=mode,
                     scale=scale,
                 )
                 self._add_actor("dipole", actor)

mne/viz/_brain/tests/test_brain.py

@@ -483,7 +483,9 @@ def __init__(self):
         ori=[[0, 1, 0]],
         gof=50,
     )
-    brain.add_dipole(dip, fname_trans, colors="blue", scales=5, alpha=0.5)
+    brain.add_dipole(
+        dip, fname_trans, colors="blue", scales=5, alpha=0.5, mode="sphere"
+    )
     brain.remove_dipole()
 
     with pytest.raises(ValueError, match="The number of colors"):