[sldev] Sculpties: Vacuum-Forming, Skittering, Zone Linking

[Kent Quirk (Q Linden)]

So it's an interesting point of view you're expressing.

To me, sculpties define a smooth mapping of the vertices of a 
well-defined closed mesh. After that, anything that happens is largely 
an artifact of the implementation and could easily vary between 
platforms or implementations.

You, as you put it, "see optimization and untapped power." You're trying 
to find ways to extend sculpties to do things like change the topology 
of the prims.

The architect in me wants to preserve the freedom to change the 
implementation of sculpties in the future as we learn more about ways to 
improve and design the implementation. If people start depending on 
implementation details to do things like drill holes in sculpties by 
abusing the way rendering works, it constrains our ability to extend the 
feature in the future. Of course, it'll probably happen whether I want 
it to or not -- but it's where I'm coming from.

In any case, seems like you're asking for sculpties to be able to do 
things that are better suited to using separate objects. Could you 
explain your motivation for wanting to extend the definition so far?

Dale Mahalko wrote:
> On 9/28/07, *Argent Stonecutter* <secret.argent at gmail.com 
> <mailto:secret.argent at gmail.com>> wrote:
>
>     On 28-Sep-2007, at 11:27, Dale Mahalko wrote:
>     > Tunnels and linked holes are technically impossible in a sculptie
>
>     PRIM_SCULPT_TYPE_TORUS
>
> But what if you need more than one hole, multiple interlinking holes, 
> or any number of holes? What if you're making a swiss-cheese sculptie? 
> I realize this rapidly becomes a discussion of topology and the limit 
> of how many hole configurations LL may offer in predefined prim types..
>  
>  
> What's really needed is a way to arbitrarily define holes (or at least 
> seams) through a sculptie mesh so that the mesh can be literally cut 
> and peeled apart into independent flexible sections that are then 
> wrapped and shaped as needed to form potentially independent meshes.
>  
> This could be done by defining a particular color as a special code 
> for "make seam here". Since sculpties don't use the alpha channel for 
> anything, seaming data can be stored in there.
>  
>  
> Conceptual diagram: Sculpties Store Seam Data in Alpha
>  
> http://img211.imageshack.us/my.php?image=sculptiestoresseamsinalit2.png
>  
> So if you need a hole through the sculptie you simply draw an 
> alpha-channel line across the color vertex image.The points directly 
> below the alpha-channel form one edge around the mouth of the seam 
> while the points directly to the right (or directly above/below, if a 
> horizontal seam on the RGB data) form the other edge around the mouth 
> of the seam. The adjoining triangles across the seam are dropped and 
> not rendered. To properly form a tunnel, two seams need to be cut and 
> the open ends of the seams go inside and pass through the interior of 
> the object. The open ends of both seams are aligned and overlap to 
> form a continuous tunnel.
>  
> Or if you want to just tear off a section of mesh from the sculptie, 
> to be used as a free-floating object always hovering in place nearby 
> the main sculptie, cut all the way around a large section of vertexes 
> and then fold the edges of that tiny patch together, so that the 
> normals all face outward to form a continuous shape. The square hole 
> in the main sculptie can just be pulled across and tucked shut to hide 
> the cutout hole.
>  
> - Scalar Tardis aka Dale Mahalko