Subject:
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Re: ldglite (ldlite for OpenGL and Linux) new stuff
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Newsgroups:
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lugnet.cad.dev
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Date:
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Sat, 5 Feb 2000 03:01:00 GMT
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Viewed:
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2844 times
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In lugnet.cad.dev, Jacob Sparre Andersen writes:
> - Different coordinate systems
>
> I don't know how many there are, but since I find the choice
> in LDraw strange, I can understand people that choose an
> alternative in later programs (despite the sillyness of it).
And earlier programs. BriCAD, L3G0, Ben's (?) POV library,
VBLOCKs (an SGI GL program) and I think LegoPS (postscript)
used different coordinates & units.
Or at least they were all different from L3G0.
> - Naming conventions
>
> What other "naming" conventions than part numbers are used?
L3G0 call a brick a "b2x4"; BriCAD called it a "b4x2"; LDRAW
was the winner hands-down by using mold numbers.
> - Using POV "modellers"
>
> This sounds like a sensible possibility. I presume that they
> are much more versatile than LEdit and the other LEGO
> oriented CAD editors. Is that true?
I've mentioned AC3D before. I have a DAT export module for
this that I used with the Throwbot leg:
http://www.lugnet.com/cad/dat/?n=154
(The export module only works if you register AC3D):
http://www.comp.lancs.ac.uk/computing/users/andy/ac3d.html
>
> Personally I dislike graphical drawing tools, even though I
> like graphical feedback when I edit LDraw and Postscript
> files, so I doubt that a typical "modeller" is the right
> tool for me (but I have never claimed to be ordinary).
Agreed. I like EMACS and graph paper. But AC3D did a good
job of making spheres on the end of an axel. I need to
add the ability to automatically generate Type 5 lines
for spheres and cylinders, using the midpoints of the
adjacent polygons as the control points.
> We should also remember that even though POV is a good
> raytracer, it is horrible for building instructions. We will
> still need a tool that can convert our files to LEGO style
> building instructions.
I did some work in making instructions from a ray-tracer.
See the instruction images at the bottom of:
http://www.gyugyi.com/l3g0/darksun/L3/jade/outpost/outpost.html
> If we choose to abandon the current LDraw editing tools and
> switch to POV, we will need to write a renderer based on a
> much more complicated file format (POV). This could be quite
> difficult, and I suspect that making a LDraw "modeller"
> would be easier than to make an instruction renderer that
> reads POV files.
Ah, but code to parse POV files already exists. True, the
nesting of the transform matricies makes it had to tell
what pixels correspond to the verticies of a triangle, but
if you don't need to CSG, and ignore reflections, refractions,
and lens distortions, you could make an LDLite-style z-buffer
renderer for POV.
-gyug
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Message is in Reply To:
 | | Re: ldglite (ldlite for OpenGL and Linux) new stuff
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| Paul: [ Tells us that we are behaving a little bit silly. ] You are probably right, but... I think that the main problem is that practically none of us are experienced CAD developers or users. Some of Paul's points: - Different coordinate systems I (...) (25 years ago, 4-Feb-00, to lugnet.cad.dev)
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