Pathfinding in Second Life

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Overview

At a high level, pathfinding provides tools and functions to enable smoother and smarter movement behavior for non-avatar entities in Second Life (for example, monsters in a game, rats in a haunted house, wisps in a fantasy forest). We refer to these entities as characters; in gaming terminology, they are sometimes called NPCs (non-player characters) or mobs (mobile objects).

Up till now, content creators had to use resource-intensive scripting workarounds to emulate intelligent character movement. With the addition of pathfinding, content creators will have a much easier and better performing way of creating characters that can move around in the world. Characters can use LSL functions to avoid obstacles, move around corners, climb inclines, and move across region boundaries: things that were very difficult or even impossible before. Pathfinding will also enable new gameplay mechanics, such as creating food that attracts monsters.

KBnote.png Note: Pathfinding is not an animation system. It does not provide a way to animate a biped or quadruped in conjunction with the new movement functionality. You must use existing methods to animate characters. Nevertheless, pathfinding enables more dynamic movement and provides a better system for controlling character movement than was previously possible. For more information on creating animations, see Animation.

User group

Please go to the simulator user group for questions related to pathfinding. Andrew, Maestro, Falcon, or Stinson Linden should be able to help you with any technical questions.

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LSL functions

The pathfinding LSL functions enable you to create characters that dynamically avoid obstacles while performing typical behaviors you might want in a game or other virtual experience, including:

  • Create - Initialize an object to prepare it for using pathfinding functions. LlCreateCharacter
  • Delete - Stop the object from responding to pathfinding functions. LlDeleteCharacter
  • Evade - Run away from a specified object or avatar. See llEvade.
  • Flee - Attempt to get a specified distance from a specified location. See llFleeFrom.
  • Navigate - Move to a specific location. See llNavigateTo.
  • Patrol - Move through a path defined by a set of "patrol points." See llPatrolPoints.
  • Pursue - Chase a specified object or avatar. See llPursue.
  • Update - Update or change the parameters associated with a character. See LlUpdateCharacter.
  • Wander - Randomly move around a specified distance from a specified central point. See llWanderWithin.
  • ExecCharacterCmd - Miscellaneous character-related functions such as stopping and jumping. See llExecCharacterCmd.
  • GetStaticPath - The only function which can be used on non-characters and on regions with dynamic pathfinding disabled. Returns a path to the goal. See llGetStaticPath

For more details, see Pathfinding LSL Functions.

LSL events

The following event is designed to react when the various pathfinding event are triggered for an active pathfinding character:

  • path_update - Triggered when a pathfinding event occurs.