- Click to place center point.
- Move cursor away from center point to define radius.
- Click to finish circle.
- Esc = Cancel operation.
- Ctrl '+' or Ctrl '-' = Change the number of segments
- Shift (before 1st click) = Lock circle to current orientation
- Arrow keys (before 1st click) = Lock Surface Normal (Up=Blue, Left=Green, Right=Red, Down=Parallel)
- Arrow keys (after 1st click) = Lock drawing direction to specific inference direction (Up=Blue, Left=Green, Right=Red, Down=Parallel/Perpendicular)
