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 CAD / Development / 7642
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Subject: 
Re: Detemining Polygon Winding (Was: New Plugin for LDDesignPad)
Newsgroups: 
lugnet.cad.dev
Date: 
Thu, 8 Aug 2002 01:36:47 GMT
Viewed: 
668 times
  
Portals. It's not backface culling, it's testing all polygons for visibility
using possible rays through the openings, or from the sides of a bounding
box. This is no longer culling based on front/back but true visibility that
is computed once at load-time, and could scale to the whole model as you
build it.

I figured LDRAW was full of holes (: but I haven't yet gained a deep
familiarity with them.

By the way, how about the new version of Moller's Real Time Rendering? It's
sure to be interesting.


In lugnet.cad.dev, Don Heyse writes:
In lugnet.cad.dev, Orion Pobursky writes:
In lugnet.cad.dev, Don Heyse writes:
I wouldn't bother.  This well known algorithm is based on an assumption
that simply isn't true for the parts files.  The assumption is that there
is one single enclosed space inside of each part.  But I think the studs
are open at one end and are positioned with the open end on top of another
surface.  This breaks the algorithm.

Yes but I'm not parsing primitive subfiles in my plugin, just quads and
triangles.

OK, but if the quads and triangles don't form a single closed surface,
or actually a bunch of closed surfaces, then the algorithm won't work.

However, like I said, if you find something that works, post the code
or the algorithm and you'll be my hero.  I don't think I'll ever add
code to parse the BFC meta-commands in ldglite.  (I just don't like
them).  But I will add code that BFCs parts automatically if someone
comes up with it.

Don



Message has 1 Reply:
  Re: Detemining Polygon Winding (Was: New Plugin for LDDesignPad)
 
(...) Oops, I guess you caught me. I knew about that one but I'm too lazy to implement it. Isn't that the method used by MLCAD? (...) Yeah, probably. Seems like only yesterday I was all excited about some code snippet of his that I found on the (...) (22 years ago, 8-Aug-02, to lugnet.cad.dev)

Message is in Reply To:
  Re: Detemining Polygon Winding (Was: New Plugin for LDDesignPad)
 
(...) OK, but if the quads and triangles don't form a single closed surface, or actually a bunch of closed surfaces, then the algorithm won't work. However, like I said, if you find something that works, post the code or the algorithm and you'll be (...) (22 years ago, 8-Aug-02, to lugnet.cad.dev)

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