John Tsiombikas <[EMAIL PROTECTED]>
writes:
> I can't see how one could use whatever scenes and objects he finds on
> the internet for anything useful. First of all, they won't be what
> you want. Ok you may find a generic dragon, or a dolphin. But in
> general you need to show specific things, not just anything you can
> get your hands on :)
>
> Even if you manage to find exactly what you need as a stock object,
> the size of the models will be random, the polygon counts probably
> will not be what you need, they may or may not have texture
> coordinates.
Well, everybody has their own needs. Personally, I probably fall into
the "testing" category more than anything else. I write software, but
I'm not very good or experienced at modelling, so it's really nice to be
able to download a spaceship or three from the net, plonk them in a
scene and render away.
I find that the issues you mention are not really much of a problem, as
it's easy enough to deal with them after loading. E.g., I typically
replace all the materials used (which is easy given that 3ds files used
named materials), and normalize the mesh size before placing it myself.
The main issue for me is that it's hard to make geometry, and that's
what all those free .3ds files provide.
E.g. example from a scene file I have:
mmap = material_map {
Ball_1 = mirror{reflectance=.8};
Ball_2 = cook_torrance{{r=.1,g=.2,b=.8, i=.6}, m=.04};
Ball_3 = cook_torrance{grey(.8), m=.04};
Glass_outer = glass{ior=1.5};
...
}
add_mesh ("../dist/models/Apartment.3ds", mmap, 11, -6,-0.05,-5, deg(-90))
The materials in that 3ds file are essentially useless, but because they
have names I can easily replace them.
> I mean at the very least you would need to import them to 3dstudio,
> fix them up and re-export them.
If I had proprietary apps like 3dstudio, I probably wouldn't be using
lib3ds... :-)
> The only real use of stock objects that I can think of is for "testing"
> algorithms, in case you're bored to tears with the bloody teapot. In
> which case 3ds is definitely the wrong format to use. Stanford provides
> great meshes in ply format, aquired with 3d scanners, you can use those.
> http://graphics.stanford.edu/data/3Dscanrep/
Man, I'm bored with them too!!! That damn dragon ... :-/
Actually those .ply files illustrate another nice thing about 3ds files:
they _do_ have more than just geometry, and that information is usable
in practice (even if you replace the materials, as I usually do, just
having the _references_ to them is extremely useful).
Ply files as commonly found tend to contain only geometry. The ply
format is fairly flexible, so maybe you _could_ do more, but AFAICS,
nobody does, and there doesn't seem to be much standardization beyond
basic geometry -- and without some (at least defacto) standardization,
flexibility isn't terribly useful in an interchange format.
**
Mind you, it would really be cool if there was a scene format without
the limitations of 3ds, which was (freely) documented, widely supported,
widely used, and easy to develop for ... but as far as I can figure
there really isn't. There have been lots of "contenders" but they all
seem to have foundered for one reason or another, and the mostly widely
used formats you find all seem to be heavily proprietary and without
good free library support.
Another point for using lib3ds is simply that it is in fact, really easy
to use: it's a straight-forward and lightweight library, with few
dependencies, which just does the loading and provides the info in a
highly usable form -- and otherwise stays out of your way. There are
other free graphics systems which support this or that format, but in
general they seem to be a _lot_ more heavyweight than lib3ds.
-Miles
--
Ich bin ein Virus. Mach' mit und kopiere mich in Deine .signature.
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