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Subject: 
Re: Flattened Primitives (was Re: 1x1 and 2x2 chess sets)
Newsgroups: 
lugnet.cad.dev
Date: 
Wed, 3 Mar 1999 18:25:57 GMT
Viewed: 
643 times
  
On Wed, 3 Mar 1999 16:36:43 GMT, "Lars C. Hassing" <lch@ccieurope.com>
wrote:

Steve wrote:
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.

It's not that simple. Together with the POV substitution string I also
have other data like the BoundingBox of the primitive, which is used
e.g. in the automatic camera positioning. I think it is troublesome
to have this kind of info in the external file too.

(I didn't claim it would be easy)  Of course, the more information
stored in a translation, the harder it is to customize.  And load into a
program to use the information.

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.

(BTW, I meant 'mistake' as in a typo or a sub-optimal approach to
modeling.)

I think they are mistakes too.
Actually there are lots of singular matrices! So many that I decided
not to burden the innocent user. L3P has a list over xz-primitives
(like 4-4disc.dat) and silently fixes singular matrices for these
primitives. You can see warnings for this if you run "l3p -check -w3"
"WARNING \"%s\" Line %d: Row %d all zeros: %s"
"WARNING \"%s\" Line %d: Y column all zeros: %s"

Ah.  I thought there would be more than four instances of this behavior.

I don't like having this list (and having to keeping it up-to-date),
but it seems that many part authors are lazy or ignorant and write
lines like "1 16  x y z  10 0 0  0 0 0  0 0 10 4-4disc.dat"

Lazy?  Ignorant?  That would be an oversimplification.  LDraw doesn't
care about the extra zeroes, it happily crunches the numbers anyway.
And it seems like the FPU might occasionally short-cut multiplications
by 0, thus speeding up rendering (that's just a guess on my part).

If L3P didn't fix these lines, you would just have a lot of warnings
from POV, which would only confuse the ordinary user. The goal of
L3P is to not have POV issue any warnings at all.
Please let me know if you experience any.

I'll be sure to.

Steve



Message is in Reply To:
  RE: Flattened Primitives (was Re: 1x1 and 2x2 chess sets)
 
(...) I agree. (...) It's not that simple. Together with the POV substitution string I also have other data like the BoundingBox of the primitive, which is used e.g. in the automatic camera positioning. I think it is troublesome to have this kind of (...) (25 years ago, 3-Mar-99, to lugnet.cad.dev, lugnet.cad, lugnet.build)

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