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[Cross-posted to original newsgroups, and lugnet.cad.dev. Followup-To
set to lugnet.cad.dev]
On Wed, 3 Mar 1999 10:11:31 GMT, "Lars C. Hassing" <lch@ccieurope.com>
wrote:
> But primitive substitution is just a hack (although a good one :-)
> If you want perfect parts, go for LGEO.
It's probably easier to make high-quality parts in LGEO, but it should
be possible to make them in LDraw, run them through L3P, and get
equivalent results.
Primitive substitution isn't a hack--it's a smarter translation.
What'd be *really* great is if the substitution wasn't hard-coded in
L3P, but was stored in an external file. That way, LGEO (or even L3G0)
parts could be easily substituted in for LDraw parts, if the user was
willing to go through the work of editing the translation file.
> Well Steve, I also checked yesterday the usage of the cone
> primitives and found your new part 6267.dat. This raises an
> interesting question about the usage (misusage?) of primitives:
>
> What you really needed was a 1-4ring3.dat primitive. It doesn't
> exist, so you very ingeniously scaled a cone with zero in Y
> to make it flat: "1 16 110 96 -10 2 0 0 0 0 0 0 0 -2 1-4con3.dat"
> (Clever trick, I must admit. You have a way with primitives.)
> However, the above line is rejected by L3P, because POV would
> complain about it and set the Y-scale to 1.0, since it doesn't
> make sense to scale anything by zero in POV's 3D world.
I should read more before posting (or save my outgoing messages, and
post them all at once). Since I just posted more-or-less the same
message. I could cancel the message, but I don't like canceling. Oh,
well.
> Should we have more primitives, or should L3P have a list of
> exceptions in order to convert a zero height cone to a ring?
Seems kind of hacky to me to hard-code exceptions. Especially since
this won't be the only place this approach is/was used, I think.
Let's see: L3P reports four other part files with singular matrices:
352.dat, 6043.dat, 4285.dat, and 3741.dat. I think these may be
mistakes -- in each case, the singular matrix is flattening either a
N-Mcyli.dat or stud4.dat. Even if they aren't mistakes, there are other
ways to write those codes.
So I guess I was wrong--so far, no one has needed to flatten a primitive
on purpose, except 6267.dat.
Since POV-Ray doesn't like flattened primitives, we should rethink the
proposed strategy of (in the future) using flattened conics to make
rings, and not creating new ring primitives. Too bad -- I hate
cluttering up the primitives directory. But if we must, we must.
Unless modifying L3P to make exceptions for flattened primitives is
really easy. If that's the case, I'd be happy flattening primitives all
day long.
Steve
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Message is in Reply To:
 | | RE: 1x1 and 2x2 chess sets
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| (...) All 3 cone primitives (4-4con12.dat, 1-4con3.dat, 1-4con4.dat) have POV equivalents in L3P. Unfortunately the 1-4 cones are clipped by a too small box, {<0,-1,0>,<2,2,2>} rather than {<0,-1,0>,<6,2,6>}. I plan on a release 1.2 in the very near (...) (25 years ago, 3-Mar-99, to lugnet.cad, lugnet.build)
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