[yt-users] Porting .ply files to Blender with colors?

[Matthew Turk]

On Mon, Feb 25, 2013 at 1:43 AM, Jill P. Naiman <jnaiman at ucolick.org> wrote:
> Hi Matt,
>
> I've tried a few different things with PLY files and no luck.  Actually, I'm
> not 100% sure if Blender really likes PLY files anyway - you can't even
> export color easily in PLY format in Blender.  So, I've given up on PLY and
> have hacked together a bit of a messy OBJ exporter:
> http://paste.yt-project.org/show/3205/

This looks nice.  We should incorporate this, or a modified version,
into the AMRSurface object.  We used to have a .obj file format
exporter, but I (incorrectly, it seems) thought the PLY format, which
can be in binary and is thus much smaller, had feature parity.  Would
you be up for making this a bit more general, and then adding it to
the AMRSurface object?

>
> I'm probably doing the colors wrong, since there's likely a nicer way to get
> actual "face" values then just taking the value at 1/3 of the vertex values,
> but it worked, so I didn't mess with it too much.

There is a simpler way, but honestly it's pretty non-intuitive and I
think the face/vertex sampling in the AMRSurface is a bit clunky.  If
you do:

surf.get_data(field, "face")

it will sample at the faces rather than the vertices.  This is also
the default behavior for getting data through the dict-like method:

surf[field]

which should be face sampled.

>
> A few other things: (1) in theory, this can set transparencies, but I
> haven't got that working as of yet, (2) the default specular (ambient?)
> color settings make for a bit of a washed-out view in sketchfab:
> http://skfb.ly/54jged0b, (3) the .mtl file is a bit too long since I'm
> essentially setting each face as a different material, when one would just
> like to use 1 material per color and set all the faces with that color on a
> specific surface plot to that material, but I haven't got that bit working
> well either.

(2) Is this something that can be controlled by the materials editor
on Sketchfab?
(3) Ah, interesting.  One could do just 255 materials, for instance,
and then that is now the colormap.

This is definitely very interesting, and would be a huge upgrade for
our Sketchfab / Blender / etc capabilities.  Thank you for sharing all
of this!

-Matt

>
> Thanks for the info, and please let me know if any of that doesn't make
> sense.
> -Jill
>
>
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