====== Train HUD ======
Passengers and drivers of trains get more information about the train they are in with a HUD.

===== Graphical driver HUD =====
The graphical driver HUD was introduced in version 2.2.0 and updated in 2.2.1.

{{:usage:ywang_trainhud_design_1.png?direct&400|}}

The HUD shows:
  * The speed in m/s indicated by the two-digit 7-segment display.
  * The corresponding speed shown as a white bar.
  * The physical speed limit (i.e. the speed limit of the wagons themselves), if lower than 20m/s.
  * The driving direction of the train as a lever
  * The throttle and brake controls of the train shown as a combined lever
  * "ATC" when ATC is active
  * "LZB" when LZB is active
  * "Shunt" when shunt mode is active
  * The signal aspect of the next signal shown by two rectangles and a number:
    * If the upcoming signal allows proceeding without any speed limit, the indicator is shown in green.
    * If the upcoming signal has a speed limit that is higher than 0m/s, the indicator is shown in orange, and the speed limit is shown as a red triangle pointing downward at the speed bar.
    * If the upcoming signal does not allow proceeding, the indicator is shown in red.
  * The status of the doors.
  * The speed current speed limit of the train (if present) shown as a red vertical bar
  * The ATC target speed (if present) shown as a cyan triangle pointing up


===== Passenger =====
Passengers only see the text shown inside the train, as configured on the onboard computer or LuaATC.

===== Text-based driver HUD =====
A text-based HUD was used before version 2.2.0. It looks similar to the following:
<code>
 [F] {B - >o< +} >|< >|<
Speed: |++++___________|> 15 km/h
Manual operation
</code>
The display shows:
  * The text that is normally shown inside the train, if any.
  * The driving direction: ''[F]'' when driving **f**orward or ''[R]'' when driving in the **r**everse direction.
  * The lever of the train:
    * ''>BB<'' when the emergency brake is applied
    * ''>B<'' when the normal brake is applied
    * ''>-<'' when the train rolls to stop
    * ''>o<'' when the speed of the train is constant
    * ''>+<'' when the train accelerates
  * The doors that are open:
    * ''>|< >|<'' when doors on both sides are closed
    * ''|<>| >|<'' when doors on the left side are open
    * ''>|< |<>|'' when doors on the right side are open
  * The current speed of the train: four ''+'' show that the train moves at 4m/s (15km/h)
  * An ''S'' in the speed indicator when shunt mode is active
  * The operation mode of the train:
    * When the train is manually controlled, ''Manual operation'' is shown
    * When ATC is active:
      * The target speed is shown similarly to the current speed of the train
      * The ATC command and delay (if any) is shown after the ATC target speed
    * When LZB is active (e.g. when the train is approaching the end of the track) **and** the train is manually controlled, ''-!- Safety override -!-'' is shown.