llCreateCharacter

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Revision as of 13:53, 16 February 2012 by Jeremy Linden (talk | contribs)
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Summary

Function: llCreateCharacter( list options );

Creates a pathfinding entity, known as a "character", from the object containing the script. Required to activate use of pathfinding functions.

• list options – Character configuration options.

By default, the character's shape will be an upright capsule approximately the size of the linkset, adjustable via the options list. The linkset must use the land impact accounting system introduced with the mesh project.

Option Default Range / Values Description
CHARACTER_DESIRED_SPEED 1 6 [0.2, 40.0] Speed of pursuit in meters per second.
CHARACTER_RADIUS 2 [0.125, 5.0] Set collision capsule radius.
CHARACTER_LENGTH 3 (0.0, 10.0] Set collision capsule length

If the value is less than twice the radius plus 0.1m, it will be set to twice the radius plus 0.1m.

CHARACTER_ORIENTATION 4 VERTICAL VERTICAL, HORIZONTAL Set the character orientation.
TRAVERSAL_TYPE 7 TRAVERSAL_TYPE_SLOW TRAVERSAL_TYPE_FAST, TRAVERSAL_TYPE_SLOW, TRAVERSAL_TYPE_NONE Controls the speed at which characters moves on terrain that is less than 100% walkable will move faster (e.g., a cat crossing a street) or slower (e.g., a car driving in a swamp).

To use _FAST or _SLOW, you must specify a CHARACTER_TYPE.

CHARACTER_TYPE 6 CHARACTER_TYPE_NONE CHARACTER_TYPE_A, CHARACTER_TYPE_B, CHARACTER_TYPE_C, CHARACTER_TYPE_D, CHARACTER_TYPE_NONE Specifies which walkability coefficient will be used by this character.
CHARACTER_AVOIDANCE_MODE 5 AVOID_CHARACTERS | AVOID_DYNAMIC_OBSTACLES Combinable Flags: AVOID_CHARACTERS, AVOID_DYNAMIC_OBSTACLES, AVOID_NONE Allows you to specify that a character should not try to avoid other characters, should not try to avoid dynamic obstacles (relatively fast moving objects and avatars), or both. This is framed in the positive sense ([CHARACTER_AVOIDANCE_MODE, AVOID_CHARACTERS] would create a character that avoided other characters but not agents or moving vehicles). Setting this parameter to AVOID_NONE causes the character to not avoid either category.
CHARACTER_MAX_ACCEL 8 20 [0.5, 40.0] The character's maximum acceleration rate.
CHARACTER_MAX_DECEL 9 30 [0.5, 60.0] The character's maximum deceleration rate.
CHARACTER_DESIRED_TURN_SPEED 12 6 [0.02, 40.0] The character's maximum speed while turning--note that this is only loosely enforced (i.e., a character may turn at higher speeds under certain conditions)
CHARACTER_MAX_TURN_RADIUS 10 1.25 [0.1, 10.0] The character's turn radius when traveling at CHARACTER_DESIRED_TURN_SPEED
CHARACTER_MAX_SPEED 13 20 [1, 40.0] The character's maximum speed. Affects speed when avoiding dynamic obstacles and when traversing low-walkability objects in TRAVERSAL_TYPE_FAST mode.
CHARACTER_ACCOUNT_FOR_SKIPPED_FRAMES 14 TRUE TRUE or FALSE TRUE matches pre-existing behavior. If set to FALSE, character will not attempt to catch up on lost time when pathfinding performance is low, potentially providing more reliable movement (albeit while potentially appearing to be more stuttery).
CHARACTER_STAY_WITHIN_PARCEL 15 Depends* TRUE or FALSE FALSE matches traditional behavior. If set to TRUE, treat the parcel boundaries as one-way obstacles (will re-enter but can't leave on it's own).

Caveats

(subject to change)

  • You only need to use one llCreateCharacter call per script, calling multiple times has no effect.
  • One script can contain an llCreateCharacter call and other scripts can exploit that with other path functions that require it.
  • llCreateCharacter status survives state changes.
  • llCreateCharacter is always required for all pathing functions.
  • If we have multiple scripts containing llCreateCharacter in the same object nothing untoward happens.
  • If multiple scripts use conflicting path functions in the same object (different prims or the same prim) one will take precedence randomly (apparently).
  • CHARACTER_DESIRED_SPEED ranges from 0.02 to 50.0.
  • CHARACTER_RADIUS ranges from 0.1 to 5.0.
  • CHARACTER_LENGTH ranges from 0.0 to 10.0.
  • TRAVERSAL_TYPE_SLOW | TRAVERSAL_TYPE_FAST | TRAVERSAL_TYPE_NONE - only use one of these parameters or omit. Defaults to TRAVERSAL_TYPE_NONE to if omitted. This affects whether a character moving on terrain that is less than 100% walkable will move faster (e.g., a cat crossing a street) or slower (e.g., a car driving in a swamp).
  • CHARACTER_TYPE_A | CHARACTER_TYPE_B | CHARACTER_TYPE_C | CHARACTER_TYPE_NONE - only use one of these parameters or omit. Defaults to CHARACTER_TYPE_NONE to if omitted. This determines which of the 4 walkability coefficients the character pays attention to.
  • The character's shape is a capsule (cylinder with spherical ends) with a length (from tip to tip) and a circular cross section of some radius. These two size parameters are what is controlled by the CHARACTER_LENGTH and CHARACTER_RADIUS params respectively.
  • Note that the characters true "length" cannot be smaller than twice the radius however you're welcome to specify a value lower than that (but more than zero) -- the script shouldn't complain.
  • The capsule is usually oriented vertically. It is possible to make the capsule lie horizontal by using an object that is long in its local X-axis, however these characters might not be able to navigate through gaps that cannot fit them lengthwise.
    • Use a vertical capsule whenever possible; horizontal capsules may become stuck more easily than vertical capsules.
  • Removing the script from a prim will not stop pathing behavior, in the same way that particles and hover text remain. To stop a pathing command use llExecPathingCmd(PATH_CMD_STOP, list empty_list).

Examples

<lsl> default { 

   state_entry()
   {
       llCreateCharacter([CHARACTER_DESIRED_SPEED, 50.0]);
   }
   
   touch_start(integer total_number)
   {
       list points = [llGetPos() + <5,0,0>, llGetPos() - <5,0,0>];
       llPatrolPoints(points, []);
   }

}

</lsl>

Notes

This function is currently in alpha testing.

Deep Notes

Footnotes

  1. ^ The ranges in this article are written in Interval Notation.

Signature

function void llCreateCharacter( list options );
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