ENH: Add optional channel name overlay to plot_alignment

doc/changes/dev/13570.enhancement.rst

@@ -0,0 +1,5 @@
+Add an optional ``show_channel_names`` parameter to
+:meth:`mne.viz.plot_alignment` to overlay channel labels at sensor
+locations in the 3D alignment view.
+
+Contributed by Aman Srivastava (:gh:`aman-coder03`) in :pr:`13570`.

examples/visualization/eeg_on_scalp.py

@@ -35,6 +35,7 @@
     meg=[],
     coord_frame="head",
     subjects_dir=subjects_dir,
+    show_channel_names=True,
 )
 
 # Set viewing angle

mne/viz/_3d.py

@@ -554,6 +554,7 @@ def plot_alignment(
     sensor_colors=None,
     *,
     sensor_scales=None,
+    show_channel_names=False,
     verbose=None,
 ):
     """Plot head, sensor, and source space alignment in 3D.
@@ -646,7 +647,9 @@ def plot_alignment(
         .. versionchanged:: 1.6
             Support for passing a ``dict`` was added.
     %(sensor_scales)s
-
+    show_channel_names : bool
+        If True, overlay channel names at sensor locations.
+        Default is False.
         .. versionadded:: 1.9
     %(verbose)s
 
@@ -942,6 +945,23 @@ def plot_alignment(
             sensor_scales=sensor_scales,
         )
 
+    if show_channel_names and picks.size > 0:
+        chs = [info["chs"][pi] for pi in picks]
+
+        # channel positions are in head coordinates
+        pos = np.array([ch["loc"][:3] for ch in chs])
+
+        # transform to current coord frame
+        pos = apply_trans(to_cf_t["head"], pos)
+
+        for ch, xyz in zip(chs, pos):
+            renderer.text3d(
+                *xyz,
+                ch["ch_name"],
+                scale=0.005,
+                color=(1.0, 1.0, 1.0),
+            )
+
     if src is not None:
         atlas_ids, colors = read_freesurfer_lut()
         for ss in src: