Where do the prims go?

[Arduenn Schwartzman]

Bit of a builder's question here, but also a sim question, a viewer question, a nostalgia question and an over-all philosophical question...

Back in the old days, when pre-mesh SL viewers were still allowed, conservative users would perceive the brave new mesh world quite differently from the trendy kids with their newfangled mesh viewers. From the old guards' points of view, the new kids would wear cubes and spheres and cylinders, sometimes tortured, always covered in weird textures implying the existence of a newer reality.

So mesh objects had prim counterparts, likely for the sake of backward compatibility. And 8 years after the non-mesh viewers had been blocked, they still manifest themselves. Sometimes you can still see their outlines when you have the Edit window open while rezzing a new object, while suffering from a slow network connection. And after a few seconds they disappear and make place for all the triangled goodies. This makes me wonder.

Where do all these prim counterparts go once the mesh has become fully visible? Do the prims disappear both from view and from my graphics card memory? Or are they merely hidden from view, yet, still making my graphics card work?

And what is, consequently, the single-most elementary object in SL? Would that be a mesh triangle? Or does it always come with a hidden from view, but ever present prim counterpart? Should the honor of being the simplest shape in SL therefore be bestowed upon the humble, yet more complex prim cube? And with regard to complex link sets such as sofas and fireplaces: would it be more efficient to use invisible prim cubes as additional particle emitter sources or sit targets rather than single invisible mesh triangles?

Edited June 17, 2021 by Arduenn Schwartzman

[Phil Deakins]

I think I've understood the question correctly but that's not a certainty. So...

The prims don't go anywhere. Prims are mesh objects, and their shapes are designed by LL. What we think of as mesh objects are the same except their shapes are designed by users. They are user-designed prims. Seeing prim shapes change to mesh shapes is merely a delay in downloading the shape to put on the prim. The viewer receives data to rez a prim, but it hasn't yet received the data of the prim's shape. So it rezzes a prim and changes its shape when it receives the data.

 

[Arduenn Schwartzman]

So you suggest there's this entity that manifests itself as a LL-designed object, because it receives the LL data first? And, as time progresses and more data comes in, then the entity manifests itself differently, because the LL-generated data gets replaced by user-generated?

By example: I rez an object called 'Mesh Triangle'. At first I see it as a cube (12 mesh triangles). But then, after a second, the 12 triangles are replaced by the single triangle that I uploaded it as. So your answer to the question would be that a series of mesh data is replaced by another series of mesh data and the original prim data is gone? Ho do you know this?

For all I know, that cube could still be around being invisible to the user, but not to the graphics card. Why do I think this could be a possibility? Well, if you make a face on a prim or a mesh object 'invisible' (set alpha to 0) it's not visible but still there for your graphics card. It still works as hard on it as on any visible surface. How do I know? I've been exploiting that apparent inefficiency for preloading textures. Maybe it's a false equivalence, apples to pears, but maybe not.

[Profaitchikenz Haiku]

Just a guess, but maybe you're seeing the lowest LOD model or physics shape first, and then the vertices of the mesh object come into view?

You can see a similar sort of thing with sculpts in a region that is running a bit slow, a sphere appears and then the actual shape.

[Gavin Hird]

The prims don't go anywhere. The renderer (the most important part of the viewer) which paints what you see in world to the screen has a pass per frame where it calculates what is obscured by other objects. So if the prims are obscured by an overlying mesh, it simply drops painting the prims into the 2D frame that is sent to your screen. The result is they appear to be hidden.

Transparency can also influence what is obscured, so the renderer also has a pass to apply transparency to objects before it finally paints out what shall be visible or not in a frame.

From a performance standpoint, remove all prims you might wear from the outfit if these prims will be obscured by the meshes you wear. The more you pile on, the harder the renderer must work to figure out what shall and shall not be visible, resulting in lower frame rates. 

Edited June 18, 2021 by Gavin Hird

[Phil Deakins]

I was going to use sculpties as an example of an LL prim shape first, followed by the same prim being shaped by the user-designed sculpty shape. But Prof beat me to it   The sphere prim you see initially doesn't go anywhere, but its shape changes. It's the same with user-designed mesh shapes.

 

[Arduenn Schwartzman]

2 hours ago, Profaitchikenz Haiku said:

Just a guess, but maybe you're seeing the lowest LOD model or physics shape first, and then the vertices of the mesh object come into view?

No, absolutely not. It's literally the type of prims you can make with Edit, not the lower LoD or physics models. I know, because it happens with mesh object I've made myself too.

[Edit] You do see the lower LoD versions too, as the higher ones still get streamed in. So, basically, the order of appearance would be this:

1. Ghost prim companion, followed by 2. Low LoD mesh, followed by 3. Medium, 4. High and 5. Highest.

Edited June 18, 2021 by Arduenn Schwartzman

[Arduenn Schwartzman]

2 hours ago, Gavin Hird said:

The more you pile on, the harder the renderer must work to figure out what shall and shall not be visible, resulting in lower frame rates. 

Then would it be prudent for LL to drop all those ghostly companion prims to mesh objects, since no more non-mesh viewer is allowed anymore anyway? Or would the improvement be insignificant? Given that these prims are still around, it's either the latter, or it's #23,951 on their priorities list, or removal would break something deeper and more fundamental.

32 minutes ago, Phil Deakins said:

I was going to use sculpties as an example of an LL prim shape first, followed by the same prim being shaped by the user-designed sculpty shape.

As for sculpties, yes. spheres tend to become visible first, which then disappear as the sculptie map loads in steps from low-res to full-res. Even though disappearing from view, these initial spheres continue to manifest themselves as physics shapes and as low-poly spheres on the world map (typically hexagonal, viewed from above). But I believe that that's an entirely different mechanism from the 'ghost companion prims' that come with mesh objects.

 

Edited June 18, 2021 by Arduenn Schwartzman

[Gavin Hird]

59 minutes ago, Arduenn Schwartzman said:

Then would it be prudent for LL to drop all those ghostly companion prims to mesh objects, since no more non-mesh viewer is allowed anymore anyway? Or would the improvement be insignificant? Given that these prims are still around, it's either the latter, or it's #23,951 on their priorities list, or removal would break something deeper and more fundamental.

 

Not sure what you mean by companion prims?

All the original prims are low poly meshes which can be morphed into many shapes. They are also quite efficient as building blocks for many purposes as they have flexible texturing and you don't need to add physics. Removing them would break a large amount of builds and content.

The absolute worst are sculpt, which they simply should get rid of. A full 128x128 sculpt map will create a mesh of 16834 vertices. Many sculpted panel plants still used throughout are made from 32x32 sculpt maps which are 1024 vertices, but often the creator have used a bigger map. A similar panel plant can be made from 12 vertices with an uploaded mesh, and is infinitely more efficient for the renderer.

What makes sculpt even worse is that a large number of the vertices are often hidden, imposing an extra burden on the renderer in the pass that calculates transparency. 

 

[Phil Deakins]

Arduenn. There are no companion prims, and no ghostly prims. There are no prims for LL to drop. You receive data for a prim, and then data how on to shape it. That's all there is to it.There is nothing left over.

[Profaitchikenz Haiku]

30 minutes ago, Phil Deakins said:

You receive data for a prim, and then data how on to shape it.

So if I'm following you, the viewer receives data for object "blah" size x,y,z at position x,y,x rotation x,y,z,s and while it's waiting for the shape data it throws up a default cube shape (or sphere if it's a sculpt), and that's the supposed companion prim, the best-guess in order to position the item whilst waiting for vertex data?

Edited June 18, 2021 by Profaitchikenz Haiku

[Qie Niangao]

We need a viewer developer to explain this. This all sounds like a rendering artifact, an object placeholder while data is downloaded and converted into geometry. I can't quite remember how the viewer used to display aberrant mesh (a yellow triangular "!" warning sign maybe?) but this feels like a step in that process.

If there's actual prim geometry defined in the sim while this is going on, I'd be surprised.

[Profaitchikenz Haiku]

1 hour ago, Qie Niangao said:

a yellow triangular "!" warning sign maybe?

Yes, it still does in exceptional circumstances when mesh won't load.

[arton Rotaru]

I don't have an answer to Arduenn's questions either, but here is a thread that explaines what he is actually talking about.

 

[Gavin Hird]

3 hours ago, Qie Niangao said:

We need a viewer developer to explain this. This all sounds like a rendering artifact, an object placeholder while data is downloaded and converted into geometry. I can't quite remember how the viewer used to display aberrant mesh (a yellow triangular "!" warning sign maybe?) but this feels like a step in that process.

If there's actual prim geometry defined in the sim while this is going on, I'd be surprised.

There is no prims, but while attached meshes are loading, it can display some really weird artifacts till the mesh is fully rendered. This is particularly evident if the viewer is on a slow connection or the asset server is slow to deliver a mesh (you can often see this in some opensim installations). Some builds may also use prims for physics, and those could show while the mesh is loading. Obviously they will be embedded in the mesh as they are never meant to be visible.

[Prokofy Neva]

On 6/17/2021 at 2:46 PM, Arduenn Schwartzman said:

Bit of a builder's question here, but also a sim question, a viewer question, a nostalgia question and an over-all philosophical question...

Back in the old days, when pre-mesh SL viewers were still allowed, conservative users would perceive the brave new mesh world quite differently from the trendy kids with their newfangled mesh viewers. From the old guards' points of view, the new kids would wear cubes and spheres and cylinders, sometimes tortured, always covered in weird textures implying the existence of a newer reality.

So mesh objects had prim counterparts, likely for the sake of backward compatibility. And 8 years after the non-mesh viewers had been blocked, they still manifest themselves. Sometimes you can still see their outlines when you have the Edit window open while rezzing a new object, while suffering from a slow network connection. And after a few seconds they disappear and make place for all the triangled goodies. This makes me wonder.

Where do all these prim counterparts go once the mesh has become fully visible? Do the prims disappear both from view and from my graphics card memory? Or are they merely hidden from view, yet, still making my graphics card work?

And what is, consequently, the single-most elementary object in SL? Would that be a mesh triangle? Or does it always come with a hidden from view, but ever present prim counterpart? Should the honor of being the simplest shape in SL therefore be bestowed upon the humble, yet more complex prim cube? And with regard to complex link sets such as sofas and fireplaces: would it be more efficient to use invisible prim cubes as additional particle emitter sources or sit targets rather than single invisible mesh triangles?

I was happier before I read this thread.

[Da5id Weatherwax]

21 hours ago, Gavin Hird said:

There is no prims, but while attached meshes are loading, it can display some really weird artifacts till the mesh is fully rendered.

And for clothing the rigging data loads last. At crowded events this means it's quite possible for somebody to TP in, their viewer to be busily downloading everything to rez everybody... and you to be completely nude to them until the rigging data for your clothes makes it through the queue to them and your garments snap into place on your body. If you've got the covered parts of your body alpha'd out of course, this isn't a concern. But folks seem to be doing that less these days. I've decided to look away from the screen or cam in on an empty piece of floor for a minute or two to preserve folks modesty more than once.

[Jaylinbridges]

11 hours ago, Da5id Weatherwax said:

I've decided to look away from the screen or cam in on an empty piece of floor for a minute or two to preserve folks modesty more than once.

I am not offended by a naked body, we were born that way.  Are your eyes showing up on the new arrivals screen?  This just strikes me as strange and funny.  I take it you hide your eyes on a nude beach too?   

Who started this naked is evil crap?  Must have been a church.

No, I'm not trying to crash a thread about prims - viewing someone's avatar skin for 15 seconds in public is not a crime. I call it a feature of Mesh and SL lag.

 

 

Edited June 20, 2021 by Jaylinbridges

[Wulfie Reanimator]

4 minutes ago, Jaylinbridges said:

I am not offended by a naked body, we were born that way.  Are your eyes showing up on the new arrivals screen?  This just strikes me as strange and funny.  I take it you hide your eyes on a nude beach too?   

Who started this naked is evil crap?  Must have been a church.

This ain't it, chief.

[Arduenn Schwartzman]

11 hours ago, Da5id Weatherwax said:

And for clothing the rigging data loads last. At crowded events this means it's quite possible for somebody to TP in, their viewer to be busily downloading everything to rez everybody... and you to be completely nude to them until the rigging data for your clothes makes it through the queue to them and your garments snap into place on your body.

The best way to witness this phenomenon is by teleporting to the cam shopping regions adjacent to big events like Collabor 88, Anthem, Kustom 9, Access. Set max bandwidth to 28k or dial in via phone, always visit on the first few days of the event, and always empty your cache before going in.

[Da5id Weatherwax]

5 hours ago, Jaylinbridges said:

I am not offended by a naked body, we were born that way.  Are your eyes showing up on the new arrivals screen?  This just strikes me as strange and funny.  I take it you hide your eyes on a nude beach too?   

Who started this naked is evil crap?  Must have been a church.

No, I'm not trying to crash a thread about prims - viewing someone's avatar skin for 15 seconds in public is not a crime. I call it a feature of Mesh and SL lag.

 

 

Nor am I. I'm perfectly OK with skin if the person showing it is doing it of their own accord. I'll look and appreciate with the best (or worst) of 'em. I just choose not to intrude my gaze on somebody unclothed, no matter how beautiful I might otherwise find them, if they have not chosen to be unclothed. It's a respect thing.