| Press "w" to toggle the GUI
to a 4 viewport display. Ensure that "3D
Snap" is active on the bottom toolbar. Access
the "Create"
panel and activate "Splines"
as the geometry type and "Line"
as the "Object Type". Use the "Perspective" view to create a line between the top arc and the smaller of the two lines in the viewport, as shown in the image. |