Re: vrml file compression

Chris Schoeneman ([email protected])
Mon, 12 Jun 1995 09:11:22 -0700

> Later, I noticed that 3DS was producing a large amount of normals data that
> I believed to be unnecessary. I added more code to remove the normal data,
> which reduced the file size by another 25% with no perceived change to the
> file. This WILL NOT WORK with some programs, but it works with 3DS. For
> example, doing the same thing to LVS files is a bad idea.

[snip]

> Theater* original: 1683979 bytes
> post-munge: 151455 bytes 91.1%
>
> * The theater was done with LVS and could not have its normals removed

Does LVS mean Lightscape's software? If so, then I'm confused about
the normals thing. Lightscape precomputes all lighting so there aren't
any light sources so you don't need _any_ normals. Early versions of
ls2iv and ls2vrml put them in unnecessarily (cos my brain went on
sabbatical).

BUT you have to tell your browser not to do lighting. WebSpace on the
sgi's understands Inventor's LightModel node. I don't know if the vrml
community has agreed upon a standard Info node extension to provide a
no-lighting hint.

In the meantime, you can change any diffuseColor field to emissiveColor
and make sure the ambient and diffuse fields are zero. This effectively
(but probably not efficiently) turns off lighting.

Cheers,
-chris