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

[Strife Onizuka]

I have a 3DM model I aim to be able to export. It is a decorative knot
I saw acting as a tassel on a piece of samurai armor. Took several
hours to just do a crude model (had to make sure I could actually tie
it first, which turned out harder then I expected considering I only
had a couple views of the knot and non of them were the critical
part). It would give any alg a run for it's money.

On 9/27/07, Dale Mahalko <dmahalko at gmail.com> wrote:
> I am looking for some sort of 3D editor that is optimized to work with the
> sculptie concept. I know what features need to exist in a proper sculptie
> editor but I don't know enough about what's available to know if it already
> exists or not. At this point what I'm looking for probably does not exist,
> and so I'm putting this here to plant a seed, hopefully for its eventual
> creation.. :-)
>
>
> 1. Vacuum-Forming
>
> A sculptie is best defined as a balloon. It is a continuous shape that is
> extremely flexible, and pliable, that can be poked and prodded and molded
> into practically any shape. The difficulty in working with a sculptie is
> finding ways to manipulate this balloon.
>
> One of the easiest ways to make complex meshes and individual prims
> translate into a sculptie, is to treat the sculptie as if it were being made
> in a vacuum-forming machine. To do this, traditional meshes and prims are
> placed inside a sculptie "inflated" to its maximum size, and the sculptie is
> then programmatically "deflated" so that it surrounds and conforms to the
> shape of the meshes/prims within.
>
> http://video.google.com/videoplay?docid=8573678537143717206
>
>
> 2. Skittering
>
> A sculptie has some special properties beyond traditional vacuum-forming, in
> that it can be stretched without limit to the maximum distance possible
> between points without tearing or pulling apart. In order for a sculptie to
> best conform to the shape of an object, and to optimize control point
> distribution, it would be useful for the points to be able to move around
> the surface of the formed shape to concentrate the points into areas of
> highest detail. This I refer to as the Skitter function.
>
> Across a large flat space there is relatively little detail and therefore a
> need for relatively few control points to define the shape. The control
> points can be allowed to stretch out and skitter away from the flat surface
> to accumulate around the edges where higher detail is needed. When modeling
> a skull as a sculptie, it is best if the control points skitter towards and
> concentrate on the face and ears, while also skittering away from the back
> and top of the skull, so that the points are concentrated in the areas where
> higher detail is required.
>
>
> To assist in the shaping of the sculpty around the objects within, it might
> be displayed as a transparent sheet draping over the objects inside, with
> recesses that are not properly matched by the sculpty given a highlight
> color so the user knows to skitter more points towards that location.
>
> Automatic optimized skittering is potentially an intensively computational
> problem, but can be assisted by allowing the user to manually control how
> points are distributed. A default sculptie mesh is deflated around a set of
> target meshes or prims, and the user is then able to "touch" the surface of
> the sculptie to define whether mesh points should skitter away or towards
> the touch point. The editor then programmatically distributes points towards
> or away from the center of the location touched, based on the strengthening
> and weakening of the elastic lines connecting the points together.
>
> Direct repositioning of the surface mesh is also possible by allowing the
> used to grab a point and then drag it across the surface of the prims below,
> causing all other points to stretch or contract around the point that the
> user is holding, and then setting a new "stretch memory" for all the elastic
> lines between points when the user lets go. In this way a mesh can be
> deformed, but then attempts to retain the deformed shape as additional
> deformations are applied. Being able to pin control points to the defined
> surface so that they cannot move would further assist in the economizing of
> point distribution.
>
>
> 3. Zone Linking
>
> Because sculpties can overlap and self-intersect without any problems, it is
> possible to create a hole in a sculptie by wrapping it around an open space
> and having the sculptie self-intersect when it has wrapped completely around
> the open area. Special handling is needed to allow for the creation of
> overlaps inside a deflation-capable editor, and one way to deal with this is
> to use Zone Linking.
>
> The internal objects which build up the sculptie are linked together to
> create zones of deflation. The sculptie deflation begins with objects being
> defined within a single zone, ignoring all other objects not selected as
> part of the initial zone. To extend out a wrap-around tentacle from the
> initial zone, a new zone is defined that links off from one of the objects
> within the primary zone. Points are then skittered across the first zone to
> spread out across the new, additional zone. The overtlap is formed by
> defining still more links and zones that reselect objects from the previous
> zones, and continuing to skitter the control points to spread out across the
> expanding chain.
>
>
> The key to making this work is that the base object from which a
> self-intersecting sculptie is to be formed, needs to be built up using
> separate meshes or prims so that each section of the object can be split off
> into its own zone. This method cannot work with a complex mesh that has
> already a hole cut through it, because the sculptie vacuum-forming can only
> wrap completely around the outside of each object within each zone..
>
>
>
> Skittering and Zone Linking can make complex sculptie objects such as an
> octopus relatively easy to produce by defining an initial body zone, and
> then defining tentacled zones that link off from objects in the main body.
>
> A traditional wooden rocking chair can potentially be modeled with a single
> sculptie by defining the seat as the initial zone, and then each of the
> wooden legs, rockers, and back-rest posts defined as a separate tentacled
> zone extending off from the seat base. Each tentacled post zone overlaps
> into other tentacle zones at the end of each post or plate, to form what
> appears to be a single solid object with multiple open spaces between the
> leg posts and back-rest posts.
>
> Other possibilities include making a gift box lid with a flower-shaped bow
> on top, and each loop of the bow is defined as a separate zone and sculptie
> tentacle extending off from the base of the bow, with each bow loop tentacle
> overlapping in the center of the bow so as to appear to be continuous.
>
> A mesh grille sculptie is simply rows and columns of zoned tentacles which
> cross through each other and extend off from a base zone formed from one
> column and one row along the edge of the grille.
>
>
> So far I don't know of any 3D editor which offers scultpie design methods
> like this.
>
> - Scalar Tardis, aka Dale Mahalko
>
> _______________________________________________
> Click here to unsubscribe or manage your list subscription:
> /index.html
>
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: raw.JPG
Type: image/jpeg
Size: 57213 bytes
Desc: not available
Url : http://lists.secondlife.com/pipermail/sldev/attachments/20070928/03af5611/raw-0001.jpeg