[sldev] 3D mesh support, vs lossless compressed sculpts

[SignpostMarv Martin]

If user-created meshes had skeletons, doesn't that mean that 
llRequestPermissions(lllGetKey(),PERMISSION_ANIMATION); would allow 
people to use BVH to animate a mesh ?


~ Marv.

Dahlia Trimble wrote:
> There must be some support for skeleton or morph animation of meshes 
> in the viewer as the avatars use those techniques. I have no idea if 
> they could be applied to other meshes.
>
> On Thu, Mar 19, 2009 at 5:54 PM, SignpostMarv Martin 
> <me at signpostmarv.name <mailto:me at signpostmarv.name>> wrote:
>
>     Didn't I read something about the possibility for sculpties to be
>     animated/manipulated with shader language code ?
>
>     How would arbitrary meshes be animated/manipulated ?
>
>
>     ~ Marv.
>
>     Dahlia Trimble wrote:
>
>         One advantage sculpts have is they require little or no
>         modifications to the SL asset storage/distribution model. I'm
>         not sure how other mesh storage methods would fit into this
>         model, but I suspect some modifications would be required.
>
>         One problem I have with sculpties is the lack of precision for
>         the vertex elements as a result of quantifying them to 8 bit
>         integers to convert them to a color. Another is the need for
>         square or rectangular arrays of vertices which makes some
>         techniques of free form mesh modeling difficult or impossible
>         as arbitrary polygons cannot be added or deleted.
>
>         Still, I am impressed with the cleverness of sculpted prims
>         and although I do share your desire for more flexible means of
>         designing meshes for SL, I am grateful that sculpties exist
>         and are being improved upon.
>
>         On Thu, Mar 19, 2009 at 4:53 PM, Dale Mahalko
>         <dmahalko at gmail.com <mailto:dmahalko at gmail.com>
>         <mailto:dmahalko at gmail.com <mailto:dmahalko at gmail.com>>> wrote:
>
>            It occurred to me recently that LL's reasoning for not
>         supporting
>            raw 3D meshes as a prim type is basically invalid, what
>         with how
>            SL functions right now.
>                The whole premise behind sculpted primitives was the
>         idea that
>            wavelet/JPEG lossy compression could be used to store "organic"
>            shapes that don't have a very definite shape or form. The lossy
>            wavelet compression of the RGB map allows the data size to stay
>            very small on the asset server, and that this could not work if
>            applied to storing and rendering mesh data.
>                However, that whole argument was thrown out the window
>         after
>            people kept demanding precision in sculpted shapes, and
>         some time
>            ago someone at LL said "Okay, FINE, we will allow the option of
>            lossless compression for RGB sculpt-map uploads" and
>         support for
>            this lossless uploading has been added into the viewer.
>                        So, uh, if lossless compression of sculpted
>         primitives is
>            permitted, doesn't that mean that there could equally be
>         support
>            for lossless compressed 3D mesh uploads, like traditional 3D
>            editors use?
>                There apparently isn't really any reason to prevent
>         mesh uploads
>            anymore, at least as long as the meshes are very small and
>         simple,
>            and the largest uploaded mesh byte size is equal to or smaller
>            than the most randomized, incompressible compressed sculpt-map.
>                        Allowing use of small meshes would be more
>         efficient for the 3D
>            renderer anyway. Since sculpts have a fixed number of
>         triangles,
>            if your model does not need the triangles for detail then they
>            need to be "bunched up" into a pile to get them out of the way,
>            possibly tucked inside the model so they don't show. But these
>            unnecessary bunched up triangles are still being processed
>         by the
>            3D renderer whether or not they are needed.
>                LL's own sample sculpt maps demonstrate this problem,
>         like with
>            the S-shaped sculpt that has a ton of prims scrunched up on
>            it, and which could drop 50% or more of the triangle faces
>         on it
>            and still look good.
>                So sculpted prims actually add to 3D scene rendering
>         lag and
>            contribute to a lower framerate and poor performance
>         because they
>            do not and cannot "turn off" unneeded triangle faces, vs a mesh
>            which just simply would not include any more detail
>         triangles than
>            the mesh actually requires.
>                        But there seems to be major LL heel-dragging
>         against implementing
>            actual 3D mesh support and making models a heck of a lot
>         easier to
>            build in external editors, vs the arcanary of sculpts that very
>            few people understand or can use effectively to reduce prim
>         usage.
>                So, I am not expecting this post will change anything.
>         But oh
>            well, I thought I would bring up this small detail for
>         discussion.
>            The sldev list has been pretty quiet lately anyway.. ;-)
>                - Scalar Tardis / Dale Mahalko
>                
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