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Subject: 
Re: New Primitive Class
Newsgroups: 
lugnet.cad.dat.parts
Date: 
Sat, 22 Mar 2003 19:48:57 GMT
Viewed: 
915 times
  
In lugnet.cad.dat.parts, John Riley writes:
My current 33089 (in PT) is a rather bulky file (55KB), so to streamline it,
I decided to make a few new primitives.  One of these was a torus with major
radius 1 and minor radius 1.

Under the current naming scheme, this primitive would be named:
t04o10000.dat
which is not in 8.3 format.

You might be surprised at how close t04o9999.dat would come.  I can't see
that it's any worse than the current t04o3333.dat file.  Actually, I think
I'm going to modify LDView to recognize nnnn in the minor fraction (where n
is 0-9) to be exactly equal to n / 9.  In all likelihood, anyone using nnnn
really means n / 9 anyway.  That would produce exactly 1 for the 9999 case.
If we modify the spec to say this, you can have your unit torus without a
new naming convention.  Programs that perform primitive substitution can
have an exact match, and the data in the file itself can be exact.


I'm tempted to name this file t04ounit.dat.  I'd make it a subpart, but it's
a true primitive, and I can see it being used in the future (probably could
be used in modelling helmets with flat tops, such as Boba Fett's and the
Stormtrooper's).

The other possibilty is to come up with a naming scheme for those tori with
minor radii larger than their major radii.  I'd call these inverted tori, as
the minor/major ratio is inverted.  Thus, using a similar naming scheme,
we'd have
iFFXRRRR.dat
where FF is the sweep as before
X is o,i, or q as before
and RRRR is the major/minor ratio (the inverse of the regular torus ratio)

I can't imagine an inverse-ratio inner torus ever being used.  It would
overlap itself.  So the o is redundant.


thus, for a maj=1 min=1, 1/4 outer torus (the one I made)
i04o1000.dat

I don't think this is a good idea.  You're sacrificing one of the precious
8.3 digits as an indicator that this is a unit inverse torus.  0 and 1 are
the only valid choices, and if it's 1, all three of the other digits have to
be 0 (otherwise it should just use the current naming convention).  While I
realize you're trying to come up with something that solves your current
problem, I don't think this is a good solution.


for a maj=1, min =2, 1/4 outer
i04o0500.dat
and so on.

As per my above comment, this would be i04o5000.dat (which of course doesn't
solve your immediate problem).


Another possibilty is
iFFXRRDD.dat
where RR.DD is the minor axis length to 2 decimal place precision
thus, the torus I made is now:
i04o0100.dat

or similarly
iFFXRDDD
now with 3 decimal place precision, but you now can't make tori with min/maj
ratios >=10

There are many more options, but these are the two I came up with that
seemed reasonable.  My personal preference is for the third (can easily
distinguish btw 1/1.133 and 1/1.125)  Any thoughts?

That would work, but I think that t04o9999.dat might be a better solution.
Remember, .9<repeating> is mathematically exactly equal to one.  Obviously
.9999 isn't exactly equal to one, but since t04o3333.dat is supposed to mean
.3<repeating>, I don't think it's such a stretch to say that 9999 means
.9<repeating>.

--Travis Cobbs (tcobbs@REMOVE.halibut.com)



Message has 1 Reply:
  Re: New Primitive Class
 
(...) I'm not terribly surprised. This is a great solution, as then, if for some reason in the future, inverse ratio tori are needed, they can use the same convention, just a different starting letter and inverting the ratio as appropriate in the (...) (21 years ago, 22-Mar-03, to lugnet.cad.dat.parts)

Message is in Reply To:
  New Primitive Class
 
Actually, it's not a new primitive, but it doesn't fit under the current naming scheme. My current 33089 (in PT) is a rather bulky file (55KB), so to streamline it, I decided to make a few new primitives. One of these was a torus with major radius 1 (...) (21 years ago, 22-Mar-03, to lugnet.cad.dat.parts)

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