[help-3dldf] Fwd: Re: Helices. Was: problems installing

[Laurence Finston]

------ Forwarded message -------

From: "Laurence Finston" <address@hidden>
To: J.E.
Date: Sat, 28 May 2005 21:40:54 +0200

> Hello again, and thank you for your help so far.

Glad to.

> The structure I would like to illustrate consists of helical components
> on several levels. 

[...]

> If such multi level structures could be created easily in 3dldf, it would 
> allow me to build up illustrations of electrical cables. These are built up
> from copper wires and tube shaped insulation materials arranged in this
> kind of multi level helices.
> 
> What do you think, would this be possible?

Yes, this is exactly the sort of thing 3DLDF is designed to do.
If you've been keeping up with the snapshots, you will have noticed
that I've added a 'helix' type, along with a couple of others.  I 
thought it would be a good idea to make it possible to have 
helices with cylindrical and conical envelopes, and I've started work on
adding 'ellipsoid' and 'sphere' for good measure.  
There are a few other types I've been wanting to add, too.
So far, it's just "skeleton" code, i.e., there are declarations, functions, 
and parser rules for declaring 'helices', etc., and performing certain
operations 
on objects of these types, but none of these operations does anything yet.

The bad news is that I'm having serious problems involving 
unemployment so it is unlikely that I'll be able to do much work 
on 3DLDF in the near future.  I hope to be able to work on it a lot 
again soon, but everything is very uncertain at the moment.

My suggestion, if you want to use 3DLDF, is to implement the functionality you
want using 'paths' and macros.  'sample0.ldf' has examples of using macros,
and the 'help-3dldf' archives has a thread about them.  They are somewhat
different from MF/MP macros, but I don't think they're hard to use. I may have
written something about them in the plain text manual I started and put on the
website.  If you have any questions, please don't hesitate to ask. If I
possibly can, I'll answer them.

If you know how to do this, you could also implement the functionality you
need in your copy of my sources.  If you were using 1.1.5.1, you have some
idea of the C++ sources, if not the Bison parser.
If you assign copyright to the Free Software Foundation, I could possibly
include your additions in the official distribution.

I'm afraid this is one of the disadvantages of using a package that's in the
process of development.  And since there are an infinite number of geometric
constructions, 3DLDF can never be finished.

Another fly in the ointment is the fact that surface hiding doesn't work yet.
This is my next major project, not counting revising the manual.
I've made a start on it, but it's a long, long road, and under present
circumstances, I'm not able to work on it.

If you're still interested, it would save me some trouble if you would
subscribe to the 'address@hidden' mailing list and post to it.  All
postings from non-subscribers are blocked, because it was getting too much
spam.  According to the list administration website, email addresses are made
unrecognizable to the programs that search the web for addresses, but I
haven't checked this.  I suppose that the ones that appear explicitly in the
messages are not disguised.  I've forwarded some of your messages to the list,
but removed your name and email address.  However, if you don't want to
subscribe, you can just keep mailing me directly.  

Sorry not to be more help.  I'm quite interested in helices for my own work,
and I wish I could devote more time to them.  You might want to take a look at
L. Nobre G.'s FEATPOST package (there's a link on the website).  He's a
physicist and may have implemented helices.  Not that I want to lose a user,
but it might provide a solution for you right away.

Laurence