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 CAD / Development / 4387
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Subject: 
Re: Some Words To BFC
Newsgroups: 
lugnet.cad.dev
Date: 
Thu, 6 Apr 2000 20:41:45 GMT
Viewed: 
7801 times
  
In lugnet.cad.dev, Leonardo Zide wrote:

> Steve Bliss wrote:
> > 
> > > Can Michael or any other programmers estimate the time savings from being
> > > able to assume all parts as BFC compliant, rather than having to check each
> > > one?
> > 
> > Good point.  We definitely *should* muddy this discussion up with some
> > real facts. ;)
> 
>  I can't speak for the other programs but if you allow a part to have
> CCW and CW faces in any OpenGL program, it's going to be slower (but as
> LeoCAD's library is pre-processed than it won't be a problem). If you
> have some parts BFC compliant and some not than it won't make a big
> difference in the total rendering time.

As someone pointed out once, it's not a big deal to get all windings the
same before passing the data to OpenGL.  Just swap the order of the
points.  For quads, switch points 2 and 4.  For triangles, switch points
2 and 3. This could/should be done while parsing the input files.  For
LeoCAD, I guess that would be when you convert them to your binary
format.

>  I'm also against requiring all parts to be BFC compliant unless
> there's a *completely automatic* way of checking.

That's good to know.

Steve



Message has 1 Reply:
  Re: Some Words To BFC  [DAT]
 
(...) I don't mind that because I preprocess the files anyway and anyone who wants to get a good speed increase should do the same. But it's not a good idea to turn on/off BFC several times and in some cases, it's nicer to have the faces reversed. (...) (26 years ago, 7-Apr-00, to lugnet.cad.dev)

Message is in Reply To:
  Re: Some Words To BFC
 
(...) I can't speak for the other programs but if you allow a part to have CCW and CW faces in any OpenGL program, it's going to be slower (but as LeoCAD's library is pre-processed than it won't be a problem). If you have some parts BFC compliant (...) (26 years ago, 6-Apr-00, to lugnet.cad.dev)

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