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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Tue, 5 Sep 2000 21:38:08 GMT
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Viewed:
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1211 times
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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.
Greetings, M. Moolhuysen.
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Message has 1 Reply:
 | | Re: 30223 contains co-planar polygons
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| (...) 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 (...) (24 years ago, 6-Sep-00, to lugnet.cad.dev)
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Message is in Reply To:
| | Re: 30223 contains co-planar polygons
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| (...) Yes, please. Fixes and improvements are always accepted! (...) Great! 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 (...) (24 years ago, 5-Sep-00, to lugnet.cad.dev)
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