Subject:
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Re: Crazy, OK Heretical Idea ...
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Newsgroups:
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lugnet.cad
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Date:
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Thu, 1 May 2003 00:28:49 GMT
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Viewed:
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2008 times
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In lugnet.cad, Xanthra47 wrote:
> We need vertex lists very badly. Current Ldraw renderers pay at least a
> 3x speed penalty right now because they have to apply a translation
> matrix to the same point in each of the polygons that intersect at that
> point. (Unless they're doing some caching, or converting to an internal
> representation that uses vertex lists, but neither is ideal) Tweaking
> the format a little bit would save those duplicate calculations. Once we
> have vertex lists we can simply send them, the polygons, textures, and
> the transformation matrices directly to the graphics hardware to chew on
> (aka OpenGL and Cg)
You might look into the LDLite language extensions -- they probably don't qualify as
true vertex lists, but they do allow you to write files in a vertex-list friendly
fashion. You can use the POINT meta-statement to define each vertex at the top of
the file, then use those points in the linetypes. Like this:
0 POINT A 0 0 0
0 POINT B 100 0 0
0 POINT C 0 0 100
3 16 A B C
Using the MATRIX meta-statement, you can do the same thing with subfile references:
0 POINT home 0 0 0
0 MATRIX default 1 0 0 0 1 0 0 0 1
1 16 home default 3001.dat
It would be relatively painless to write a program to translate LDraw files to this
'vertex-listed' LDLite format. Once the translator is created, the parts library
could be translated, and used by an LDLite-capable renderer, especially if it had a
user-definable include path.
Uhh, let me rephrase that:
The translator could read the files in ldraw/parts (and /p, and /p/48, and /parts/s),
and save them to /parts.ldl (and etc.).
Steve
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Message has 2 Replies:
 | | Re: Crazy, OK Heretical Idea ...
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| Geez, it'd be nice if I finished my thought... (...) If the renderer allowed the user to change the include/search path from the default: ldraw\parts;ldraw\p to ldraw\parts.ldl;ldra...dl;ldraw\p The renderer would pick up the translated parts first. (...) (23 years ago, 1-May-03, to lugnet.cad)
| | | Re: Crazy, OK Heretical Idea ...
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| I just did a double take : ) YEA, vertex lists ! I was working up to proposing just this sort of addition to the standard. Since these already exist can they be grandfathered into the 1.0 document that Orion has prepared ? -JSM PS. I was so annoyed (...) (23 years ago, 1-May-03, to lugnet.cad)
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Message is in Reply To:
| | Re: Crazy, OK Heretical Idea ...
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| (...) Yep. I've actually written code to convert between several of these and they don't really fit the bill : ( The ones that are commonly used are proprietary and these kinds of programs typically need workstation-level computing power to work (...) (23 years ago, 28-Apr-03, to lugnet.cad)
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