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Subject: 
Re: Detemining Polygon Winding (Was: New Plugin for LDDesignPad)
Newsgroups: 
lugnet.cad.dev
Date: 
Thu, 8 Aug 2002 01:29:02 GMT
Viewed: 
2365 times
  
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 2 Replies:
  Re: Detemining Polygon Winding (Was: New Plugin for LDDesignPad)
 
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 (...) (24 years ago, 8-Aug-02, to lugnet.cad.dev)
  Re: Detemining Polygon Winding (Was: New Plugin for LDDesignPad)
 
"Don Heyse" <dheyse@hotmail.spam....away.com> skrev i meddelandet news:H0I44E.2vE@lugnet.com... (...) An idea: Drawing with a software Z-buffer it's trivial to note _which_ polygons are the finally visible ones (at every pixel). Those are on the (...) (24 years ago, 8-Aug-02, to lugnet.cad.dev)

Message is in Reply To:
  Re: Detemining Polygon Winding (Was: New Plugin for LDDesignPad)
 
(...) Yes but I'm not parsing primitive subfiles in my plugin, just quads and triangles. -Orion (24 years ago, 8-Aug-02, to lugnet.cad.dev)

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