Sculpt: Option to mask front faces only using Lasso and Box Mask

This adds a property that checks the normals of each vertex against the
view direction to decide if they should be masked (similar to the
"Front Faces Only" option works for brushes.

Reviewed By: sergey

Maniphest Tasks: T77637

Differential Revision: https://developer.blender.org/D8448

release/scripts/startup/bl_ui/space_toolsystem_toolbar.py

@@ -1226,22 +1226,32 @@ class _defs_sculpt:
 
     @ToolDef.from_fn
     def mask_border():
+        def draw_settings(_context, layout, tool):
+            props = tool.operator_properties("paint.mask_box_gesture")
+            layout.prop(props, "use_front_faces_only", expand=False)
+
         return dict(
             idname="builtin.box_mask",
             label="Box Mask",
             icon="ops.sculpt.border_mask",
             widget=None,
             keymap=(),
+            draw_settings=draw_settings,
         )
 
     @ToolDef.from_fn
     def mask_lasso():
+        def draw_settings(_context, layout, tool):
+            props = tool.operator_properties("paint.mask_lasso_gesture")
+            layout.prop(props, "use_front_faces_only", expand=False)
+
         return dict(
             idname="builtin.lasso_mask",
             label="Lasso Mask",
             icon="ops.sculpt.lasso_mask",
             widget=None,
             keymap=(),
+            draw_settings=draw_settings,
         )
 
     @ToolDef.from_fn