[Opensim-users] Question: Avatar Draw Weight

[Kay McLennan]

Hi Gwyn,

Thank you for the avatar draw weight resource links!

Best,
Kay


On Wed, Aug 29, 2012 at 11:45 AM, Gwyneth Llewelyn <
gwyneth.llewelyn at gwynethllewelyn.net> wrote:

> Dear Kay,
>
> You might wish read how Avatar Draw Weight is calculated:
> http://wiki.secondlife.com/wiki/Mesh/Rendering_weight
>
> Base calculation is indeed linked to the number of triangles an avatar
> has, and, of course, any attachment will add to that value. But extra
> settings like glow, flexi, and some scripts will add even more.
>
> But remember: except for scripts on attachments, Avatar Draw Weight is a
> measure of *viewer-side *lag, i.e. how big an effort *your* graphics card
> has to make in order to render an avatar, and *not* an impact on the *
> server* where OpenSim is running. While an avatar with tons of
> attachments needs to download them first — which will create some impact on
> the simulator, as it starts sending all that data to you; the more avatars
> with attachments on the region, the more effort the simulator has to do —
> after they're fully loaded, they should have no impact on the simulator any
> more (attachments are phantom). Scripts, of course, running server-side,
> are a different story. Scriptless attachments should not make a huge
> difference on the simulator (except during the initial load).
>
> On the other hand, viewers will definitely notice the impact of high draw
> weights. This is mostly noticeable on low-end, old graphics cards, which
> cannot process so many triangles per frame. It's not so easy to find specs
> for each and every card out there, and to know where the threshold is.
> Modern, high-end graphics cards can render so many polygons per frame that
> I would seriously suspect that they would not notice much of a difference.
>
> A simple rule of thumb: Draw weight of 1000 = just the standard avatar =
> 7500 triangles
> Everything above 1000, divided by 5, gives the amount of extra triangles
> (assuming no glow, no flexiprims, etc.) So an avatar with draw weight of
> 25,950 would have at most 12,500 or so triangles. 18 of those would come up
> to 225,000 triangles. As far back as 2001, high-end graphic cards would
> easily handle 60-100k triangles per frame, assuming 30 FPS (
> http://www.gamedev.net/topic/55764-how-many-triangles-do-most-computer-games-render-per-frame/).
> In 2004, 400-500k triangles at 30 FPS seemed to be more typical (
> http://www.gamedev.net/topic/253770-how-many-triangles-can-your-engine-handle/
> )
>
> Raz Welles has a thorough explanation of where all those triangles come
> from:
> http://razwelles.blogspot.pt/2012/06/opensim-and-mesh-understanding.html He
> quotes a "typical" graphics card being able to render 1.5 million triangles
> at 33 FPS. His articles is from June 2012, so you can see how the amount of
> triangle rendering per second has been growing steadily in the past decade.
>
> Still, all these numbers are merely a rough guideline. LL's own engine on
> the viewer might have performance limits as well — i.e. it may not be able
> to send all those triangles to the OpenGL layer quickly enough for the GPU
> to tender them. OpenGL, in return, also has a limit on how many triangles
> it can send. And finally, these counts are usually for untextured triangles
> — add texturing, and the number obviously drops!
>
> However, I think it's a relatively safe bet that anyone with a graphics
> card of around 2010 or so should easily view those 18 avatars with Avatar
> Draw Weight of 25,950, as easily as if they had no attachments, and still
> get 30 FPS, if they don't turn on shadows or the more sophisticated
> advanced lighting options on the newest viewers.
>
> I hope this helps.
>
> Cheers,
>
> - Gwyn
>
> On 29/08/2012, at 16:18, Kay McLennan wrote:
>
> OpenSim-User List Serve Colleagues,
>
> I currently use the Zen and Phoenix viewers (3) and noticed how the
> "avatar draw weight" feature in these viewers reveals a dramatic increase
> in my draw weight whenever I add any attachments to my avatar (read:  prim
> hair, face light, sculpt shoes or clothes, etc.).  More specifically,
> without any attachments, my avatar has a draw weight of 1,000 but with the
> above listed attachments has a draw weight of 25,950.  Further, when I was
> at an [OpenSim] in-world meeting last week, I observed how many of the
> approximately 18 avatars in attendance had even higher draw weights.
>
> What is the significance of the avatar draw weight when it comes to region
> performance and lag?  More specifically, if a region can support 18 avatars
> with fairly high draw weights, could the region support double the number
> of avatars if everyone used an avatar than only had a draw weight of 1,000?
>
> Thank you in advance.
>
> -- Kay McLennan
>
>
>
> --
>
> "I'm not building a game. I'm building a new country."
>
>   -- Philip "Linden" Rosedale, interview to Wired, 2004-05-08
>
>
>
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>



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