llSensor

llSensor is a function in Linden Scripting Language (LSL) used in the Second Life platform to configure and perform proximity sensing from within a script. It enables an object to detect nearby avatars or other objects within a defined radius and, optionally, to filter results by type, name, or specific identifier. A sensor can be configured to emit repeated updates at a defined rate or to report a single update.

The function works by specifying filters for what to sense and how often to report results. Typical filters include the type of entities to detect (for example avatars, objects, or both), an optional name filter, an optional unique identifier filter, the sensing range in meters, and the update rate in seconds. By adjusting these parameters, a script can focus on particular targets and control the frequency of reports to balance responsiveness with performance.

When enabled, llSensor causes the environment to generate sensor events for each detected entity that matches the configured filters. Each event provides details such as the entity’s type, its unique ID, its displayed name, and its distance from the sensing object. The sensor can be disabled or reconfigured by calling llSensor again with new parameters.

Usage considerations include the impact on script performance and sim resources. Larger ranges and higher update rates increase processing load and memory use, potentially affecting script performance and teleporting behavior. llSensor is commonly employed in proximity-based interactions, access control, and scripted AI-like behaviors in virtual environments. See also related sensor functions such as llSensorRepeat and other proximity APIs in LSL.