Invisiprims Interfere with Occlusion Culling

I reported this as a "bug" already, but decided to make people aware of it anyways.

Just rez an invisiprim, make it big enough to cover at least one Octree node, then look through the invisiprim from various angles. You can see objects and terrain being culled as you move the camera around. It's a nice way to see Occlusion Culling at work, but it obviously shouldn't be happening.

I think I know WHY it happens, since invisiprims are basically a hack of the rendering engine, where the prim is marked as "solid", even though you can see through it. Thus, many things aren't drawn behind the invisiprim.

This is why I think a feature similar (or better?) to invisiprims should be built-in. I'm pretty sure this has been requested before, but it's becoming more and more necessary. This hack won't work forever.

Ooh, heh. That little complication never occurred to me. I haven't gotten a chance to see how much this side-effect would occur in practice -- hopefully not too often if most folks are using just a few fairly small invisiprims on their avs.

That said, Delta, I do agree with your sentiment 100%. We really need an official, non-hacky-buggy solution for people who want part or all of the default av skin hidden.

Pretty please, Lindens?
** does cute foxie-beg to Lindens for jagillionth time **

Yah, invisiprims aren't alpha, so they occlude stuff. Since LL is making such an effort to keep invisiprims working, I suppose they could special-case invisiprims in the OC code.

Even after they come up with a workaround, I think they'll need to keep them around for a while, there's just too much content that uses them.

Yeh, what would you need?

1. Avatar filter layer. Add a layer that acts like a multiply filter for the avatar, you'd select it like the tattoo and it'd multiply R G B and A on the avatar's skin with this layer.

2. Constructive solid geometry. Let you define the prims in an object as combining in more ways than just "union"... allow "intersection" and "complement" as well.

What else?

I don't really think this is a problem. Culling the world around you can actually be a neat effect. ^.^
Besides, do you ever really expect to see invisiprims THAT big in use without it being on purpose?

i'm with Feynt that would be neat, you could set them around your land/house and enjoy a nice unclutterd view.

Hmm yes, that is exactly what I think I will do. I was hoping you culd do just this with an alpha prim, but you cant, which makes sense. So I hope this does get labelled as a feature, not a bug, as my avatar attached invisiprims are never big enough to cause culling, but I would like to surround my property with culling.

...

Holy Hana! You could use this to block out ugly builds, like a Bush Sign! Oh, Oh, it's a feature not a bug!

I haven't tryed this on the preview grid yet, but... I placed a invisiprim inside the transarent glass of my windows. I hope this makes culling work and since the glass is textured you really can't see much past it anyway.

As for the AV. How about having skins support a alpha channel?

This would allow for all kinds of things.
headless horesmen, bullet holes, missing limbs.

Just add prims to make up the missing space.

Yeah, the skins-with-alpha-channels idea gets thrown around a lot. Seems to be the simplest official approach to solving some of the same problems as invisprims. Sadly it doesn't really help people who use invisprims for commercial high-heeled shoes etc. where the buyer won't be willing/able to hack up their existing skin, clothes, etc.

Back on-topic, I don't really mind invisprims causing occlusion, though I'd rather they didn't; the only unexpected benefit that I can imagine is that they let you unclutter your skyline in a performant way, but since occlusion culling supposedly affects land segments (and who knows, in the future perhaps sky octants, etc) you'd perhaps get a less hacky and more artistically predictable and flexible effect from just placing a nice inwardly-opaque skybox around your property.

Woot I hope they keep this nice new feature.

@grumble Loudon

We need to help Linden find a good compromise solution to this. While some form of avatar invisibity is needed to create some particularly wild designs the problem is that alpha solutions will lead to truly invisible avatars and in turn to lots of new griefing methods. Limiting the alpha to maybe 10% will still have problems because all these creative designs will have this ghostly form of your avatar still visible .. ugly, right?

We don't want our requested solutions creating even more problems than we already have.

I use! I has been using giant Invisiprims to create invisible room in the sky for some times now. With combination of invisiprims and transparency, you can make the whole room invisible from the outside, yet very solid and fulled of furniture once you step in.

But that wouldn't affect you then would it? As the culling would remove the things you can't see anyway, and also unclutter your outside view.

I like this possibility, I want this 'bug' to remain as it will be VERY handy! I moved from Web-Worm because my beautiful lake view suddenly had an ugly-ass build in the way, just invisiprim it away and I'd have a wonderful landscape outside, with a really good frame-rate to boot! I've been making my tinting windows so that they go opaque in order to take advantage of occlusion culling, but I could use invisi-prims instead, keeping a nice view AND improving performance!

You could wear invisisocks.
That's actually cool. I'm altready using big one-sided invisprim panels around one build to hide some ugly alpha stuff... if it hid the whole build that would definitely be a bonus.

I'll have to experiment with this.

This is a non-issue because this "problem" already exists with invisiprims. You can even hide your label with invisiprims which you wouldn't be able to do with alpha.

How about this option... an extension of the one I proposed earlier? On the clothes and tattoo textures, have a checkbox called "Filter". If you check it, then that texture is used as a multiply filter on the underlying textures. This would not only allow you to create "alpha clothes", but you could also have tattoos that just darkened or tinted the underlying skin tone: an "alpha tattoo" would be solid white where a normal tattoo would be transparent, and would have tinted sections where you want the pattern to show.

Hmm, taking a look at this culling 'bug', it seems that the culling effect with invisiprims isn't great, I made an invisi-prim box in the test area which you can get to here and look around (you'll know when you hit the walls )

NOTE: The top of the box is phantom so you can get in and out =)

It looks to me though like flexi-prims aren't being culled at all, at least in this test? Is that consistent with anyone else's findings? Even in the distance they are all still visible, not a good thing as they are client rendered even if they should be culled!

[edit]
Just noticed, it does cull them eventually, but it takes a while, over a minute for me!

Well... not really. Alpha on the skin is quite different from alpha on clothing, where you'd expect the alpha channel to be used as it currently is, for revealing the (i.e. skin) layer underneath, not actively erasing the layer underneath.

On top of which, people might reasonably be attached to their own choice of socks...

The issue is that the occlusion culling doesn't just hide builds. It hides terrain too (well, reportedly it does, though I've never seen it happen) and, as it becomes more efficient in the future, any amount of other stuff including the sky, to the point where at some mythical future point it's 100% efficient and occluded areas don't even get a GL colour buffer clear and you get to see a flickering GL backbuffer where your occluding invisprims are (think DOOM idspispopd/noclip). I think that this isn't the solution/hack you're really looking for.

There are already other more controlled parcel-skyline-clearing feature requests outstanding.

I doubt they'd remove the sky IMO, besides, if this hack is being used actively to hide neighbouring builds then they'd like make sure it isn't broken completely. Besides, my view is mostly skyline where I am now, so I'd be happy just to see the horizon outside

Your absolutely right, considering how fast they implimented Havok 2 we should count on feature requests to accomplish what we want, not new bugs that are alrdy implemented... :-/

Replying with equal amounts of sarcasm, you're right, we should rely on hamstringing another hack to replace an existing hack that itself gets broken EVERY PREVIEW RELEASE.

Alpha on the skin (tattoo) is also necessary for hiding or revealing things like facial hair on male avs, so current alpha is going to have to remain unblemished for compatibility with existing skins. that's why I'm proposing a "filter" option.
While wearing prim heels?

"This isn't the hack you're looking for. You don't need to see his culling list. Move along."

Whoa, what was that?

The Toon has power over mundane minds.

Cool.