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Subject: 
Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
Newsgroups: 
lugnet.cad.dev
Date: 
Thu, 30 Sep 1999 15:52:26 GMT
Viewed: 
533 times
  
onyx wrote:

the biggest problem with the LDraw parts/primatives library is that they
weren't modeled in a robust modeling app... laying out all vertices by hand
made it possible for every type of human error or preference to play a role in
the library's creation... (i know my parts wouldn't pass a CW/CCW test) we've
all created bowties, concave polys, concident verts, etc... even elements
created by me in 3DSMAX and converted using MAX2DAT were not checked for
"normal-friendliness"...

  I was curious, how do you add a stud to a part if you're using MAX2DAT
? Can it be done in 3DS or you have to edit the part later ?
  I thought that we've agreed that the new parts would have to pass L3P
tests for coincident verts and bow-ties, isn't this required ?

true 3D programs don't deal with infitintely thin objects well... anyone who
has ever built a doom level knows this ("hall of mirrors", for the
experienced)..
but many of our primatives are infiniteley thin (4-4cyli.dat) and were created
to be used as 2-sided objects with zero thickness... this way they could act as
either an outside *or* inside surface with normals facing in both directions...
this won't work with the direction we're headed in..

  If we had a good editor with things like csg, all of those problems
would be solved. Editing files by hand will produce errors, it's hard to
make sure that all surfaces are correct.

making the programs deal with the innacuracies and correct them "on the fly" is
wrong... totally re-rengineering the library is practically impossible.. but
there is a real issue getting started here.. and it's only going to get worse..

  You make it sound like this is the end of the world. :)

Leonardo



Message has 1 Reply:
  Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
 
(...) MAX2DAT isn't really meant to be a comprehensive part authoring tool... it's easy to build simple objects (like a 2x2 tile or 1x1 round plate) directly in LEdit with primatives... but objects like complex technic pieces, wheels, etc often have (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)

Message is in Reply To:
  Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
 
There are commands in 3DS and 3DSMAX to "unify" normals (normals are what we're discussing... the vector that points perpendicular to a face, indicating which side is "out", which side is shaded or rendered)... i would assume there is documentation (...) (25 years ago, 29-Sep-99, to lugnet.cad.dev)

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