Subject:
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Re: 30223 contains co-planar polygons
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Newsgroups:
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lugnet.cad.dev
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Date:
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Wed, 6 Sep 2000 14:48:47 GMT
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Viewed:
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1095 times
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In lugnet.cad.dev, Manfred Moolhuysen wrote:
> In lugnet.cad.dev, Steve Bliss writes:
> > One more comment (to everyone, not Dave) about overlapping rectangles, and why
> > not to use them. When this approach is used simply as a shortcut so the
> > author doesn't have to figure out more vertices, they can generate notice
> > artifacts (ie, errors) in programs that do 'shading', such as LDLite and
> > L3Lab. This is noticable when the edge of one polygon intersects another
> > polygon, but not at the second polygon's edge. This can cause a line to
> > appear in the second polygon.
> >
> > This is noticeable in the 1x5x4 inverted half-arch. See <part:2339>.
>
> Axel Poqué has already submited an update for this particular part. I've been
> giving it a "second opinion" adding a fix for the ghost lines mentioned above.
>
> In my opinion this part isn't an example of overlapping faces. What happened
> in the case of part 2339 is that the outer face of the arched wall was simply
> copied to form the inner face of that same wall. This was done without editing
> the inner face, where 4 LDU should have taken of the top and of both sides,
> compensating for wall and top-lid thickness. Because the inner face still
> extents all the way to the outer skin of the part, gost lines emerge.
True, this case isn't an example of coplanar, overlapping polygons. Good
catch.
But it is an example of what can happen when you take shortcuts that have
no visible effect at the time.
No offense meant to James--the number of parts he wrote was incredible.
Especially when you consider that he was creating the LDraw system at the
same time he was writing the parts.
Steve
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Message is in Reply To:
 | | Re: 30223 contains co-planar polygons
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| (...) Axel Poqué has already submited an update for this particular part. I've been giving it a "second opinion" adding a fix for the ghost lines mentioned above. In my opinion this part isn't an example of overlapping faces. What happened in the (...) (24 years ago, 5-Sep-00, to lugnet.cad.dev)
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