README - strlen Version 0.4.0 - Geodesic Dome Strut Length
Copyright (C) 2004-2010 dondalah721@yahoo.com (Dondalah)

Xdome is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

Xdome is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

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	Free Software Foundation, Inc.
	51 Franklin St, Fifth Floor
	Boston, MA  02110-1301, USA
-------------------------------------------------------------------

Strlen is a program to help you analyze the structure of a
geodesic dome in all of its variations.  The program is not
optimized for speed but is written to illustate the mathematics
of a geodesic dome.  Each low level subroutine is written in
two phases.  Phase I generates the vertices of the dome.
Phase II joins the vertices into struts.  In most of the lower
level subroutines, you will see two loops representing each
phase of the build process.

First, run the strlen program without the -s parameter to
see summary statistics for a dome.  Then add the -s
parameter to see the location and length of each strut
in the sphere.

This directory contains the generator program, called strlen.
The verify directory contains three programs to visualize
the output of strlen.  Read the README file in the verify
directory concerning the verify and spin programs.

The output of strlen is piped into verify and spin as follows:

        strlen -c1 -pi -f3    -s | verify
        strlen -c1 -pi -f3    -s | spin
        strlen -c1 -pi -f3 -b -s | verify
        strlen -c1 -pi -f3 -b -s | spin
        strlen -c1 -pi -f3 -e0.75    -s | spinecc
        strlen -c1 -pi -f3 -e1.5     -s | spinecc
        strlen -c1 -pi -f3 -b -e0.75 -s | spinecc
        strlen -c1 -pi -f3 -b -e1.5  -s | spinecc

To see the syntax for strlen, use the -h parameter.

        strlen -h

To install strlen,
	First install xdome
	Run instsl
	Then install the verify programs
	The default parameters for strlen are
	   class 1, icosahedron, frequency 3.

The struts for a single face are repeated for every face
in the sphere.  You can see this by noticing the node
numbers, and strut lengths.  They repeat themselves
throughout the sphere.  Pick a pair of node numbers and
trace their occurances throughout the sphere.

The strlen program has a few minor differences with
Richard J. Bono's dome program.  The dome program
is an excellent program to use with the povray graphics
engine.

In strlen, an eccentric dome uses a length of 1.0
for the major axis.  That is, the distance from the
origin to the vertex is 1.0.  The ratio between the major
and minor axis is the -e parameter.  If the eccentricity
parameter -e is greater than 1.0, it is a vertical
elipse.  The z axis is the major axis.  If the
eccentricity parameter -e is less than 1.0, it is a
horizontal elipse.  The y axis is the major axis.

When you add the -d parameter for strlen to give
you a true diameter, make sure you double check the
strut lengths, when you also add the -e parameter
for eccentricity.

If you want to imagine what a home would look
like as a geodesic dome, you will need to imagine
the sphere truncated at or near the equator.
Homes are frequently built as class I, frequency 3,
icosahedron domes.  You can truncate this dome
above or below the equator.

Some homes are also built as class I, frequency 3,
icosahedron buckyballs, truncated above or below
the equator.  Truncating a buckyball dome means
that you have to truncate five hexagons at the
equator.

If you want to construct a class I icosahedron from
the strut lengths in the strlen program, use the
following command without the -s parameter:

      strlen -c1 -pi -f3 | less

To see other polyhedra, both class 1 and class 2 domes,
change the -c1 and -pt parameters to other values.  The
summary output of strlen is sufficient for building a
dome, because the triangles are repeated throughout the
dome.

For example, let's say you want to build a dog-house for
your best friend as a geodesic dome.  You want to measure
the struts in milimeters for greater precision.  You want
the dome to be 1.2 meters in diameter.  You want to decide
between frequency 2, 3, and 4.  You want to compare a buckyball
to a geodesic dome.  You want to compare class 1 to class 2.
Compare the following listings.  Read the summary statistics
at the end of each listing.  The -d parameter is a diameter
of 1.2 meters, measured in milimeters.

      strlen -c1 -pi -f2 -d1200 | less
      strlen -c1 -pi -f3 -d1200 | less
      strlen -c1 -pi -f4 -d1200 | less
      strlen -c1 -pi -f3 -d1200 -b | less
      strlen -c2 -pi -f2 -d1200 | less
      strlen -c2 -pi -f4 -d1200 | less
      strlen -c2 -pi -f6 -d1200 -b | less

Then compare the domes visually with the following
commands:

      strlen -c1 -pi -f2 -s | verify
      strlen -c1 -pi -f3 -s | verify
      strlen -c1 -pi -f4 -s | verify
      strlen -c1 -pi -f3 -s -b | verify
      strlen -c2 -pi -f2 -s | verify
      strlen -c2 -pi -f4 -s | verify
      strlen -c2 -pi -f6 -s -b | verify

Remember to truncate the dome at or near the equator.
When you truncate a buckyball, some hexagons are
truncated in half to be level with adjacent pentagons
or hexagons.  You can build a small buckyball dome
from plywood or translucent plexiglass.

With class 2 domes, the triangles at the equator have
to be truncated in half to be level with the ground.

To de-install strlen, run deinst.

To see documentation about the xdome programs, browse
doc/xdome.html.

If you encounter problems, please send me:

	A detailed description of your compile steps.
	A detailed description of the problem.
