#SL Server-Scripting News Update Week 7

Oskar Linden says the voice package running on the Blue Steel and Le Tigre release channels was fixed to clean up extra voice information being sent during region crossings. With the fix crossings should be a hair faster.

Server Beta Meeting

Magnum got the Phase I region crossing change over to multi-threading.

Osker says they flubbed this roll. The main trunk code did not get rolled into the release channel packages before they were loaded into the release channels. So all the code running on the main channel is not part of the code in the RC’s.

Lorca Linden

Lorca introduced himself as an associate producer at the Lab. He came on board about 5 months ago. He primarily works on the new pathfinding project. He is the voice in the video: Pathfinding Sneak Peek.

Lorca describes the new Pathfinding feature as a collection of new LSL calls and viewer tools. The purpose of them is to allow you to create lots of things that can intelligently navigate the SL world.

Alpha Testing

Lorca, Andrew, and Falcon came to the Server Beta meeting to talk about how residents could participate in the testing.

Obstacle Course in ADITI

Adding pathfinding to robot avatars is not yet part of this project. It is being considered for ‘down the road.’ The key there is the word considered. That means the Linden have not committed to providing pathing for avatars/bots.

For information about how to help with testing see: Pathfinding Alpha Testing.

Known Issues

The Known Issues posted on the wiki page a couple of days ago and in my previous articles have mostly been fixed. So, they have been taken off the wiki. See: Pathfinding Alpha Release Notes.

Testing Maze in ADITI

One major known issue right now is that if you teleport into a pathfinding region, it may crash. They have a hacky fix but are hoping to get enough data for a real fix. One should remove scripted attachments and HUDs before tp’ing into a test region.

This means one needs to tp to Sandbox Wanderton or Sandbox Newcomb and walk or fly into the test regions.

  • secondlife://Aditi/secondlife/Sandbox%20Wanderton/108/42/36
  • secondlife://Aditi/secondlife/Sandbox%20Newcomb /114/140/36

Since the Lindens are publishing the PathTest region names and SLURL’s all over expect lots of people to tp into the PathTest regions. I have to wonder if that is deliberate or if the Lindens just didn’t think about it when the posted the SLURL’s.

Havok AI

I haven’t worked with Havok code. The Lindens say this new pathfinding is based in Havok’s AI. When you watch the video, you’ll likely be surprised how fast the system finds a path.

Vector or Way Points

Havok generates a series of way points. However, the list of way points is not going to be available to the LSL script, which the Lindens say would be useless as the path can change quickly. Paths are updated dynamically.

User Group

One if the interesting points is that Lorca will be creating a User Group for Pathfinding. Expect to see it in the next couple of weeks. I expect that is when we will see the Project Viewer too.


Not that lag is ever an issue… right, but the question came up. The pathfinding consumes about 50 microseconds per frame. If you test this on the ADITI grid you’ll be disappointed. Those servers are using a debug version of the software and are slower. Lorca says things are running about 1/10 or 1/15 of the normal speed. Under heavy load conditions, pathfinding can run at half frame rate because it does intense validation every frame.

Navigation Mesh & Pathing Control Panel

Lorca says they have used pathfinding with a ‘load’ of ants without problems. The new functions require far less resources than any previous type of movement animation. Falcon Linden says, We currently see a single pathfinding character consume roughly 50 microseconds per frame. More depending on what it’s doing.

Converting Link Sets

If you are wondering what converting a link set does, Falcon says the conversion completely replaced its physics representation.  The link set becomes a character, somewhat like and avatar.

Land Impact Cost

The new pathfinding characters will use the new Land Impact cost system. The new viewer tools will allow one to determine the cost.

The physics cost of a pathfinding objects will be some yet to be determined fixed cost. Thinking about it, all the prims in the link set convert to a single collision capsule. So, more or less prims would change only the size of the capsule not the number of collision surfaces. Increasing the number of surfaces to be checked for collision increases the calculation cost for the physics engine. Since there will only be the one capsule per object surrounding all the link set prims the calc load is basically independent of prim count.

Animation of Link Sets

The pathfinding functions do not animate the link set. However, typical animation works with pathfinding objects.

Rock Monsters

The rock monsters in Linden Realms do not use pathfinding. They were the inspiration for developing pathfinding. Pathfinding using LSL was far too difficult.


At this point no collisions are reported. Falcon is working on detecting collisions now.

Volume detection is a type of collision detection. Currently it is not available. But, Falcon says it eventually will be.

Caveats and Such Stuff

Pathfinding is not working under water. Falcon Linden doubts they will be able to get it working before release.

When is the release? The release is when it is done. We are not going to get and ETA or timeline at this point. There are too many things that can go wrong.

Objects that are pathfinding will stall if they attempt to enter a full parcel. May be at some point they can navigate around a full parcel, but not by initial release. For release 1, they will probably ban pathfinding objects from pathing into no-entry parcels.

Pathfinding cannot backup. If the object back tracks, it will try to turn around.

Pathfinding does not handle banked turns. One will have to handle that with standard scripting.

Pathfinding has no energy aspects. This means the batteries don’t run down. It keeps on going and going, like a bunny.

Pathfinding supports bridges and tunnels. Arbitrary flight is not supported. Flight can be done with invisible platforms  and columns. The pathfinding is volumetric, meaning, I think, that is it mostly 2D but will floow a surface. At some point it may be possible to go up a wall and walk on the ceiling.

For detection the pathfinding object will detect as an Active Object, but the Lindens at the meeting were not certain. The Lab may add a character/object type.

One can have one navigation mesh per region. All pathfinding agents can use it. Viewer tools will need to be added for working with the navigation mesh. Estate managers can place a nav mesh. Then, if I understood correctly, others with permissions can edit the nav mesh.

Lorca Linden: anything that you build which is not explicitly marked as pathable will be considered an obstacle by a pathfinding enabled character.

New tools coming to the viewer will make it easy to convert existing roads to navigable paths.

One can make pathfinding vehicles. One can sit on pathfinding objects.


Oddly I didn’t hear much conversation about griefing. I asked about it but either they or I don’t understand. I can imagine building a rezzer that rez’s a 20 prim ant and sends it on its way. About a million ants later parcels all over the place will be filling up.

Lorca says, ‘we are also providing tools for estate managers (and anyone who owns characters) to see all pathfinding enabled characters on a region and delete / edit them.’

Falcon explans farther, ‘we’ll have a single panel where you can select any number of them and return at once.’

A little playing in the test regions and I found it is possible to trap pathfinding objects. One can do a sort of under the stairs thing.


We have an amazing new feature. The new functions will change how animals and vehicles work in SL. It should be fun.

Leave a Reply

Your email address will not be published. Required fields are marked *