Hoochie Hair

oh my!

*runs*

PHOTOSHOP causes lag??!!!!

Hmm...you gotta be kidding, right?

I've noticed this as well. A Fashion Show & Tell once ground to a very slow crawl when one of those huge primmy evening gowns showed up. (I think there was an avatar inside it cuz it moved, but they were so covered in lilac lagginess it was hard to tell.) People don't tend to wear the primtastic clothing every single day like they do the hair, but some people are more accessorized than Las Vegas Drag Queens.

Yeah, but most fashion shows are lag hells anyway. I haven't seen one where everything moves smoothly.

I think that the hair toss is what is causing most of the lag. I know on TV when a gorgeous supermodel tosses her hair it usually causes the slow motion to kick in. Maybe that's a feature of Second Life?

As a person who routinely has 400+ prims attached to his avatar, I'd like to appologise for the sim lag I cause.

Yet another phrase heard only in SL

Read his original explanation, he is confused, and it is understandable if you do not realize the hair attachments are made out of prims. Standard hair is done using textures, so to a new player might not realize that this is caused by prims and not a texture (thus, the Photoshop connection). Photoshop does not cause lag, but giant textures created in any paint program certainly can.

Again with that faux blush lol. BTW, many people don't know this, but Pendari is actually made completely of prims.

I wear them too. I intend to keep wearing them, unless I know the sim I am in requires the additional resources. No apology required.
I just mentioned this because I never realized the dramatic affect this can have, and suspect many others didn't either.
It was explained to me that any object attached to your avatar becomes physical.
Physical cut tori are the worst thing in SL. As is any number of intersecting cut prims...including cubes.

This doesnt jive with some other stuff I've found about attachments. Attachments are "physical" in the sense that the avatar is effected by physics and the attachments move with it, *but*, attachments are also phantom... The primary reason torii are so bad for a sim is dealing with collisions and physical interaction, which is not an issue with attachments.

What can the dramatic effect of this particular style of hair attachment be attributed to? It is definitely not the only lag inducing attachment, just a prime example.

You know WAY more about this stuff than I do. I am fairly ignorant when talking about this stuff. So please correct me if I am wrong. But....this is what was shown to me:

default
{

touch_start(integer total_number)
{
llSay(0, (string)llGetStatus(STATUS_PHYSICS) );
}
}

Drop that script into a non physics prim on the ground. Then touch the prim. Then wear that prim and touch it again. It will show status physics. It seems that even if they are phantom they still report as physical, and thats probably why they effect sim FPS.

Hee hee hee

I'm not denying they are physical, they clearly are.

The issue is that just being physical alone shouldn't cause the type of performance loss you are seeing. Attachments basicly should only have a minor impact on sim performance, as they are essentialy just a cosmetic thing, unless:

An insane number of prims are involved. I routinely wear 400+, and have not noticed any signifigant sim FPS drops when I enter sims (In sims I have land, I monitor the stats... I can check things easy enough). Less than 200 for a hair attachment shouldn't do it.

A ton of scripts are doing things. Again, I'm not seeing why this should be an issue in a hair attachment, but I could be wrong.

Textures. Textures can drop sim FPS if a ton of different, high-res textures are used.... This *could* be an issue in a hair attachment, but I doubt it.

Beyond this, I'm not understanding it.

I've been to furry avatar contests and such. Those can drop a sim's FPS a good bit, but you are talking about *thousands* of prims, with many textures, and often a good number of scripts, spread over a dozen or more AVs. One single hair attachment shouldnt be capable of causing this level of performance drop.

I actually encounted this when I was building on Cape Destiny. It was right after the update and an AV that came over to watch me build was wearing a wig of (at the time newly available) twisty curly rings.

There was a very noticable difference in update speed - BUT - only when they were in view.

I tested this by turning my back to them at all times as I built

When they took off the twisty ring wig - voila - back to normal... I don't think it was so much a lag problem as in the actual game lagging - but an issue with the client trying to draw them (think about it, intertwined twisty rings.......)

Either way - I didn't jot down any server stats, so I can't back that up one way or the other...

Siggy.

Ok, now its starting to make a little more sense...

If turning your back on it causes it to go away, yes, its client lag, not sim lag. The initial post seemed to suggest the sim was lagging, however.

Its not so much the number of prims or even the shape, exactly, that's causing it. It's the fact that the more complex, organic, and tortured the shape is, the more polygons are needed to render it. As any computer game designer (or dabbler) can tell you, polys = performance. People who do the 2 percent twist trick on cylinders to get around LoD deterioration can unintentionaly play hell with client performance by doing this, if they do it alot.

Torii, particularly in some of their more distorted itterations, require a large number of polys to render correctly, and dont get LoD'ed properly, as far as I've been able to tell.

...a maze of twisty passages, all alike...

</GEEK>

150 twisted, hollow, and cut torii? And you wonder why it causes lag?

The answer is that it isn't lag, it's low FPS (lag is high latency). Most people's PCs cant render something like that very well @_o. It's all the roundness.

When your video card draws a 3d scene, all those prims get converted into tens or hundreds of thousands of small flat triangles.

If the prim already has flat edges, such as with a cube, pyramid, or prism, it takes *very* few triangles to make the shape. For example, a non-hollow cube only takes 12 triangles (less if the invisible ones are culled, which I'm not sure SL does) since it draws two triangles per face (to make a square), with six faces.

If the prim has *any* rounded edges, the video card has to then be given a whole bunch of tiny flat triangles in order to make the shape actually appear rounded.

Think of what happens if you approximated a cylinder with a tall hexagonal peg. Now add more sides to make it more round. Now keep adding more sides until it actually starts to look around. Each time you add another side, you're adding at least two more triangles to represent that extra side (ignoring the complexities that happen to the top and bottom surfaces).

Things get even worse when you're dealing with spheres, now you have to add many many triangles across two directions on the surface. Torii are the same as a sphere in this regard.

It gets even worse when the torii (or any shape) are hollowed (now both sides must have separate triangles (basically doubling the number needed).

And then finally, stretching them into long strands will require even more triangles to maintain a curvy shape with the greater needed level of detail.

Therefore, a good rule of thumb for video rendering performance is is:

straight edged prims = fast

hollow prims = slightly slower

curvy prims = slow

curvy hollowed prims = slowest

curvy twisted revolved hollow prims = a very unhappy video card

The real reason they are reported as physical is that they are nailed to an avatar, which itself is physical, and counts as one prim as far as Havok is concerned. Havok is not actually aware of any of the prims in attachments. What people are calling "lag" is really not lag at all, in this case - it is low FPS.

I have noticed the effects of prim hair on several occasions - it tends to have lots and lots of little ringlets, and it absolutely murders my framerate the instant it comes into view. One of my avatars has ~140 prims, but most of them are of the 12-triangle variety Kex described (i.e. they are resized cubes.) Compare that to a bunch of rings and torii. SL has to generate many times more triangles for curved surfaces, which takes more CPU time. Then it has to upload all those vertices and faces and texture offsets to the video card in something OpenGL calls a "display list," and that takes longer to transfer over the AGP bus. It has to upload the entire collection of triangles once every frame. Then the GPU has to compute texel coordinates for a polygon with tens or even hundreds of vertices instead of just twelve.

I notice that when I am flying in a vehicle, SL doesn't even bother to render torii (like the tires stacked at the Balance rezzing area) and any prim that is relatively small. As soon as I get out of my plane, they show up. Kind of a pain to run into a huge stack of tires you can't even see, but I appreciate that they are doing it to keep my framerate up.

But... but...

Twisty hair is pretty!

*smacks myself upside the head, so others won't have to*

Yeah... it's absolutely hilarious to see these people complain about lag. When really, it's just client FPS they're ruining.. for everyone they're hanging around with their long prim chains and gajillion spiked bracelets, prim "piercings," and such.

Sometimes I couldn't bite my tongue and just let them know what exactly it was they were unaware of -- but they love their attachments so much they didn't care and continued to prance around, lagging everyone's client. Doesn't usually hit my system too bad...

but I guess it was like leisure suits back in the day.

Hmmmm... maybe a right-click/hide option on an AV in your field of view, which would instantly hide all attachments and turn the AV to gray would be a fix here.

Little Miss Hoochie Hair can still prance around like she's the hottest thing since sliced bread, but we could easily tell our clients, "thanks, but no thanks... I've seen enough".

- Ace