Dummy is an auxiliary object used for scene optimization, scripts and other purposes.

When an object is linked to a dummy near it, the object tree search is faster, thus the game itself performs better. A dummy has a variable called "clip distance" which determines the distance from which the dummy and its children are not drawn anymore.

The editor also supports Hierarchy Dummy object type. This is a dummy object, created in the center of the current (multiple) selection bounding box. The currently selected objects are then automatically linked to it. The tab in the editor panel is then switched to Properties so that the clip distance can be set.

Hierarchy Dummy can be also created using INSERT hotkey.

Example:

In this example, all of the objects linked to the Hierarchy dummy cease to be drawn as soon as the distance between the camera and the dummy center exceeds 50m.