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 CAD / Development / Organizations / LDraw / 4739
Subject: 
Re: Why quads? Re: L(EGO)Draw parts - 4th batch
Newsgroups: 
lugnet.cad.dev.org.ldraw
Date: 
Thu, 23 Sep 2010 16:17:23 GMT
Viewed: 
25333 times
  
In lugnet.cad.dev.org.ldraw, Don Heyse wrote:
I see.  So what you really want to do in LDView is ignore the Type 5
lines (at least for smoothing) and smooth wherever there's no Type 2
edge lines between the triangles (and quads).

Actually, no.  That is indeed a long-term goal, but it is hampered by two
things.  First of all, it's a lot of work.  Secondly, the current algorithm is
actually useful to part authors, since it can visually highlight missing
conditional lines.  (Of course, since the current algorithm has bugs, that
decreases its utility for this purpose.)  If I implement the new smoothing
algorithm you suggest, I'll retain the current one as an optional one for part
authors to use, while making the new one the default one.

My planned fix for the bug in the current algorithm is to add dummy entries in
my "type 5 map" used for the smoothing.  So, when I build the map of type 5
lines that is specifically used for smoothing and nothing else, I'll insert
entries between adjacent co-planar triangles.  I believe that this should be
straightforward, but I haven't really investigated yet.

--Travis


Subject: 
Re: Why quads? Re: L(EGO)Draw parts - 4th batch
Newsgroups: 
lugnet.cad.dev.org.ldraw
Date: 
Thu, 23 Sep 2010 17:56:29 GMT
Viewed: 
25884 times
  
In lugnet.cad.dev.org.ldraw, Travis Cobbs wrote:
In lugnet.cad.dev.org.ldraw, Don Heyse wrote:
I see.  So what you really want to do in LDView is ignore the Type
5 lines (at least for smoothing) and smooth wherever there's no
Type 2 edge lines between the triangles (and quads).

Actually, no.  That is indeed a long-term goal, but it is hampered
by two things.  First of all, it's a lot of work.  Secondly, the
current algorithm is actually useful to part authors, since it can
visually highlight missing conditional lines.  (Of course, since the
current algorithm has bugs, that decreases its utility for this
purpose.)  If I implement the new smoothing algorithm you suggest,
I'll retain the current one as an optional one for part authors to
use, while making the new one the default one.

My planned fix for the bug in the current algorithm is to add dummy
entries in my "type 5 map" used for the smoothing.  So, when I build
the map of type 5 lines that is specifically used for smoothing and
nothing else, I'll insert entries between adjacent co-planar
triangles.  I believe that this should be straightforward, but I
haven't really investigated yet.

Hmmm, it seems to me that any algorithm that can find the missing
Type 5 lines (in order to create the dummy entries) should be able
to find *all* of the Type 5 lines.  Some missing lines is just a
special case of all missing.  So just include them all in the dummy
list and use that for the smoothing instead of the other list.  If
you want to retain the debugging features you can give each one a
tag that labels them as either real, dummy, or missing.

Then, maybe long term, you can do the lotsa extra work to switch the
Type 5 line drawing over to the dummy list as well.  And at that point
maybe the standards committee can declare Type 5 lines obsolescent,
making part authoring just a wee bit easier.

Don


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