Special:
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[DAT] (requires LDraw-compatible viewer)
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Subject:
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Re: Conditional lines on sloped wedge parts 43720 and 43721
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Newsgroups:
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lugnet.cad.dat.parts
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Date:
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Wed, 27 Apr 2005 00:08:52 GMT
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Viewed:
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4307 times
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In lugnet.cad.dat.parts, Niels Karsdorp wrote:
> In lugnet.cad.dat.parts, Lars C. Hassing wrote:
>
> > In lugnet.cad.dat.parts, Steve Bliss wrote:
> >
> > > I'm pretty sure that's going to be the problem with *any* partition of this
> > > surface into polygons. Having a mathematical description of the surface would
> > > be good, because then we could potentially create a primitive for the surface,
> > > and rendering programs could substitute a smooth-curve construct for the
> > > primitive.
> >
> > I have made a 43720.inc for the test of the coming L3PPARTS.
> > The mathematical description of the surface is:
> > 80x + 40y + yz = 0
> > and I have used the POV primitive quadric:
> > quadric {
> > <0,0,0>, <0,0,1>, <80,40,0>, 0
> > clipped_by { box { <-20,0,-40>, <0,20,40> } }
> > }
>
>
> Looks good.
> Should we create a new primitive with the next dimensions:?
> 2 24 0 0 1 0 1 1
> 2 24 1 0 -1 0 1 -1
> 2 24 0 0 1 1 0 -1
> 2 24 0 1 1 0 1 -1
> and a POV-quadric version in the coming L3PPARTS.
>
> As the outer twisted surface of the parts with this shape are
> pretty the same size, the inner surface differs among these parts
> (in 43720/43721 the inner surface has a z-size of 72,
> in 45407 the inner suface has a z-size of 76).
> With a general primitive it can be stretched to any dimension.
Good idea with a twist primitive (twist.dat ?).
Perhaps it would be simpler if it were only in one octant:
2 24 0 0 0 0 0 1
2 24 0 0 1 1 1 1
2 24 1 1 1 0 1 0
2 24 0 1 0 0 0 0
POV code would be:
//x - yz = 0
quadric {
<0,0,0>, <0,0,-1>, <1,0,0>, 0
clipped_by { box { <0,0,0>, <1,1,1> } }
}
/Lars
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