Wednesday, August 8, 2012

Dance Lag and Pathfinding

Dance Lag and Pathfinding 120808

Susie Chaffe alerted me to something that is happening today that could affect dance lag. Pathfinding is being implemented. Huh? What is that? With Susie's help here is what I know:


The Firestorm website helps understanding what Pathfinding is:

"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 are very difficult or even impossible before. Pathfinding will also enable new gameplay mechanics, such as creating food that attracts monsters.

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." 


Again from the Firestorm website:

"Pathfinding & Region Performance
Once your region has been updated today, it will have Pathfinding running on it. Until your region has been optimized, this may have a performance impact. Linden Lab has assured me the impact will be at worst 4ms on main regions and 1ms on homesteads and at best won't be noticed. In layman's terms, this is around 18% max of region performance. In order to optimize your region, you will need a viewer with pathfinding tools; currently these tools are only available in a LL Beta Viewer.

Your options will be to A) optimize your region; B) turn Pathfinding off on your region; or C) do nothing. Instructions for the first two options below...

Only Region Owners and Estate Managers can enable/disable Pathfinding on a region. Parcel owners can optimize their parcels on a Pathfinding enabled region."

So, as I understand it, Pathfinding uses some of the server resources for managing script time. If you look at the SL Knowledge Base article on improving viewer performance way at the bottom you will see a reference to 22 ms for a server. This is the maximum amount of script time that a server can handle and still deliver 45 frames per second (SL's maximum frame rate). If you own a region like I do, you can see the server script time with details for every script on the region. Avatars wearing scripted items also show up. This is a tool we used during the last Dance Festival to control server demand. You can also look at the total server script demands with your viewer. On Firestorm enter ctrl+shift+1 to get the statistics bar. Scroll down to see the server FPS.

So adding Pathfinding increases server demand in terms of script handling. This means that servers will have fewer resources to handle avatars and other scripts ... i.e. implementing Pathfinder with no change in number of avatars and scripts on a sim MAY increase lag. YUCK.

If you want to manage Pathfinding see the SL Wiki or the Firestorm website.

Now for some opinion. I love dancing, but I am becoming more and more a technology geek and I don't like it. Dancing is beginning to be like being on a treadmill. The better you want to be the more you have to learn about the underlying technology. Maybe this will lead to an opportunity for someone who can optimize regions so dance clubs and dance shows can provide dancing with the best possible conditions.


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