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 CAD / Development / 6895
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Subject: 
Re: A comprehensive LDraw object model
Newsgroups: 
lugnet.cad.dev
Date: 
Mon, 11 Feb 2002 20:09:30 GMT
Viewed: 
510 times
  
"Kyle McDonald" <kmcdonald@bigfoot.com> skrev i meddelandet
news:3C671582.8010404@bigfoot.com...

[...Occlusion culling...]
You could take this to the extreme and even try to tag the geometry
based on whether it is part of the top, bottom, front, back, left,
right, or inside of the part.

If the parts are BFC compliant, there's no need to tag for 'top', 'left' etc.
as this information is already there in the surface normal (with much better
detail!).

Tagging for 'inside', 'outside' could be useful. In BlockCAD I can tag each
polygon/line with a 'detail level' value - if the renderer is set to level 1,
no polygons (or lines) with a higher detail level are drawn. In BC this is
mainly used to draw a block with/without decoration.

The typical levels for LDRAW parts could be:

0 - wireframe outline
1 - outside surfaces
2 - studs outside surfaces
3 - inside surfaces
4 - ???

But it's a big job going through all parts, and add the tag information, it's
probably better to try to deduce inside surfaces with a program.

--
Anders Isaksson, Sweden
BlockCAD:  http://user.tninet.se/~hbh828t/proglego.htm
Gallery:   http://user.tninet.se/~hbh828t/gallery/index.htm



Message has 1 Reply:
  Re: A comprehensive LDraw object model
 
(...) Well again BFC is only useful for culling surfaces that face away from you. It doesn't really do anything for faces that face you but are blocked by other faces. When I talked about top, left, right, etc, I was envisioning some system by which (...) (22 years ago, 11-Feb-02, to lugnet.cad.dev)

Message is in Reply To:
  Re: A comprehensive LDraw object model
 
(...) Yes, What you're describing does sound like BFC to me. As someone else (travis I think?) said, BFC is a useful optimiziation for reducing the number of surfaces that need to be drawn. But it's not the same thing I was talking about. BFC (...) (22 years ago, 11-Feb-02, to lugnet.cad.dev)

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