[Opensim-dev] Mesh to primitive converter

[Dahlia Trimble]

I've heard of a tool that once existed that could recreate a tri-mesh (all
polygons are in the form of triangles) object and reproduce it in SL with
triangular shaped prims. I think it was a combination of a blender script
and a LSL script. The problem with such an approach is the relatively high
cost of prims in SL. I cant remember the name of the tool but I suspect some
careful googling and/or searching the SL forums might get you there.
Sculpties are rather limited in what shapes they can reproduce, but I think
a tool that could divide a complex mesh into multiple sculpties might be an
easier way to accomplish what you want.

As far as the server is concerned, all it needs to know is that an asset is
in a certain place/orientation in the scene and how other objects should
collide with it. One could potentially design a custom viewer which rather
than rendering prims or sculpties, could reference some attribute of the
scene object, say the object name or description which could contain
alternate rendering instructions, and display a custom mesh in it's place.
The collision proxy could be constructed in a cruder form of normal prims.
Such an approach would work in an unmodified OpenSim region, and even in SL,
but would require a special viewer.

On Thu, Feb 12, 2009 at 2:39 PM, Mircea Kitsune <
mircea_the_kitsune at hotmail.com> wrote:

>  I hope this list is a good place to discuss this, I have thought of this
> feature as an addon for Opensim possibly something that could be in the core
> at one point. I'm not sure if what I have in mind is possible as I see it or
> not, but I think this feature would allow awesome graphics and revolutionary
> styles of buildings in SL (excluding realXtend which has direct mesh
> support). What if a 'mesh to primitive' converter could be created which
> would allow a user to import a mesh in-world in the forum of many primitives
> arranged next to one another to simulate that exact shape?
>
> Lets say I model something in a 3D modeling application and export it as a
> .ase model. I would place the model file in Opensim's bin folder then from
> the console write something like "importmodel mymodel.ase". Opensim would
> read the model, see how it's made and create primitives to respect that
> shape as close as possible (a box prim for every face). For instance, if my
> mesh was a 5 side cylinder and I'd attempt to use this tool, Opensim would
> generate 5 tapered boxes arranged like this<http://img252.imageshack.us/img252/1299/meshexampleig3.jpg>
> .
>
> No converter could probably be smart enough to use primitives like
> cylinders, spheres or any other types in places it could use them in, so
> every mesh would be represented from boxes tapered and positioned
> accordingly... basically a box primitive would represent each face. The
> converter could also place the clear texture on the hidden faces on the
> insides of the object and automatically link everything into a linkset. Also
> the UV mapping of every specific face of the model could be set as the
> texture mapping on every box, so one could just upload the texture after
> 'importing' the model and place it on the object.
>
> I don't know how that could be done but the idea seemed too interesting to
> keep for myself. Sculpt prims could not reach such a level of detail nor
> contain any holes in the model so this would allow realXtend-like meshes in
> the normal Opensim / SL (of course under a reasonable number of polys
> otherwise the converter could use thousands of boxes). What do you think?
>
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