draw deformation cutoff line in previews

web_backend.py

@@ -25,6 +25,7 @@ from head_extension_app import (
     APP_DIR,
     crop_head_neck,
     ct_window,
+    draw_cutoff_line,
     fit_image,
     load_dicom_volume,
     preview_deform_2d,
@@ -549,6 +550,7 @@ def start_job(kind, worker, owner=None, params=None, remember_user_task=True):
 def make_preview(input_dir, angle_degrees):
     volume = load_dicom_volume(input_dir)
     before = crop_head_neck(sagittal_mip(volume))
+    before = draw_cutoff_line(before, volume.shape[0])
     after = preview_deform_2d(before, float(angle_degrees))
 
     canvas = BytesIO()