8.4 - Cockpit Display Updaters

A cockpit display updater is a C++ object that updates part of a GL Studio cockpit display (HUD).

An updater examines the entity state and sends the cockpit display object or its agent the appropriate message. All updaters send their values as text strings, as required by GL Studio cockpit displays.

VR-Vantage provides updaters for the cockpit displays it ships. However, you can use the VR-Vantage Toolkitand GL Studio to replace updaters or add custom updaters to be used with the supplied cockpit displays or your own cockpit displays. Custom updaters must derive from DtGlStudioVrlAttributeUpdater or DtGlStudioObjectAttributeUpdater. Updaters are created using a creator object. New updater creator objects are registered with the factory.

Creators have a name and a protocol. This is because updaters that work with DIS entities do not work with HLA entities. You can generate multiple updaters by using the shared source technique that is used elsewhere in the VR-Vantage Toolkit. (For more information, please see 6.2.2 Using Shared Source Files for Simulation Drivers.) The supported protocols are DtDis, DtHla13, DtHla1516, DtHla1516e, and Object. The updater factory is in the DtSharedCockpitSettings object. Registering a new creator is done through its registerUpdater() function.

VR-Vantage provides the following cockpit display updaters:

• Object Protocol:
  • AOA-Angle of Attack. Returns the pitch of the entity clamped (-5 to 30 degrees).
  • FeetAGL-Feet Above Ground Level. Returns the feet above the terrain (or buildings below).
  • FeetMSL-Feet Above Mean Sea Level. Returns the altitude above sea level.
  • FeetPerMinute. Returns the climb rate.
  • KilometersPerHour. Kilometer per hour.
  • MilesPerHour. Miles per hour.
  • KnotsPerHour. Nautical Miles per hour.
  • Pitch. Returns the pitch of the entity clamped (-180 to 180 degrees).
  • Roll. Returns the roll of the entity clamped (-180 to 180 degrees).
  • Yaw. Returns the yaw of the entity clamped (0 to 360 degrees).
  • Value. This is a special updater in that it will send any value to the cockpit display once and then never again. It's used to configure initial setup and to turn display components on or off.
• DtDis, DtHla13, DtHla1516, DtHla1516e Protocol:
  • Headlight. Returns the headlight state of the entity as true or false

Updaters can exist in the simulation thread, owned by the GL Studio Visualizer, or in the render thread, owned by the GL Studio cockpit display object.

Updaters that live in the simulation thread have access to the entire simulation state in the entity state repository. These updaters are updated at the same rate as the network thread (approximately 15 times per second). The values that these updaters send are not smoothed in the cockpit display. These updaters are derived from the DtGlStudioVrlAttributeUpdater and have a protocol of DtDis, DtHla13, DtHla1516, or DtHla1516e.

Updaters that live in the render thread are owned by the GL Studio cockpit display object. They have access to the cockpit display object's smoother. This smoother is updated by the simulation thread and the position, velocity, acceleration, and rotation are smoothed between updates. The render thread updaters update their values approximately 60 times per second. These updaters are registered with a protocol of Object.

Note

It is important to install new updaters after the display engine is initalized. Connect to the display engine object's post_initialzie signal to be notified when it is done initializing. Then install your updaters.

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