Subject:
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Re: Rendering implementation details
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Newsgroups:
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lugnet.cad.dev
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Date:
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Sat, 29 Jan 2005 16:17:33 GMT
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Viewed:
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1902 times
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In lugnet.cad.dev, Mark Tarrabain wrote:
> But the idea I was envisioning was something like this...
>
> ...
What you are describing is in fact a very old and basic edge
rendering algorithm, which can be found in most detailed
textbooks on computer graphics. CAD style and wire frame
rendering went out of style during the 90's, so some recent
"fancy eye-candy" textbooks fail to cover it, but look it up
in any of the old classics like Foley/van Dam or Hearn/Baker
and you will find the very same idea you presented:
Keep a list of edges, associate them with adjacent polygons,
find the edges that are adjacent to both a visible and a
non-visible polygon and draw them. This will give you a good
contour of any object, convex or not, without the need for
any hardwired stuff like conditional lines.
I have a hard time adjusting to the fact that the majority of
LDraw parts were created without consideration to winding.
A large amount of existing computer graphics algoritms fall
flat on their faces if you have no knowledge of what is
inside and outside of objects. I am glad to see this issue
being resolved with the new LDR winding standard.
Stefan G
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Message is in Reply To:
 | | Re: Rendering implementation details
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| Okay.... having had a day to think about it and a night to sleep on it, I think I've figured out something.... But it would only work if the optional lines were incident to edges of polygons that are part of the object being drawn. I'm not sure if (...) (20 years ago, 25-Jan-05, to lugnet.cad.dev)
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