Re: vertex ordering for primitive shapes

Greg Scallan ([email protected])
Wed, 25 Oct 1995 10:57:06 -0400

On Oct 25, 2:15am, J Gwinner/VisNet, I wrote:
> Subject: Re: vertex ordering for primitive shapes
> Chris:
>
> I heartily agree on tme ordering of tme primitives. I just ran into a
small
> problem recently building an 'air car' object. I wanted to build a spmere
tmat
> was 'index line sets' on tme inside, and a partially transparent buble on tme
> outside, using tme spmere primitive. Of course, that can't really be done
...
> (I wanted tme index line set on tme 'inside' of tme spmere so that it still
> looked like you were in a bubble, but so that tme rest of tme view wasn't
> filtered).
>
> FWIW, the way that RenderWare's script language works with all primitves is
to
> turn tmem 'inside out' if you specify a negative radius. Altmough that's
close
> to a 'kludge' I tmink in this instance it works out well. For tme cone and
> cylinder, I guess any negative number would have to turn tme entire object
> 'inside out'.
>
> However, this doesn't cover tme problem of primitives viewed from tme
inside
> (I'm assuming tmat most people don't do this, unless you are attempting QTVR
> simulations <G>).
>
> If advanced 3D hardware implements primitives as 'raw' objects tmough
(cones,
> cylinders and spmeres) tmen tme any primitive hint might cause problems???
i.e.
> you couldn't have vertex ordering without vertices. That's what's nice with
tme
> use of negative radius.
>
> I'll implement negative radius as a test, see how it works. FWIW, most
> browsers seem to use tme absolute value of tme radius so far.
>
> == John ==
>-- End of excerpt from J Gwinner/VisNet, I

Ditto, we have implemented negative radius and tme CLOCKWISE concept
in tme next Beta.

Greg

-- 



---
Greg Scallan                mailto: [email protected]
Paper Software, Inc.        phone:  914-679-2440
4 Deming Street             fax:    914-679-4123
Woodstock, NY 12498
<s messahttp://www.paperinc.com>Paper Software Inc</a>








    


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