simon-git: polyhedra (master): Simon Tatham

Mon Jul 8 19:19:21 BST 2019

TL;DR:
  136fbc3 Migrate all these programs to use Python 'argparse'.
  64fb3a6 mkpoints.py: tidy up progress messages.
  bba236c cleanpoly.py: clean harder.
  f59ab63 canvas.py: provide an HTML output mode.
  2c24635 mkpoints.py: add a projective mode.
  8bdb8fe New script to construct zonohedra.

Repository:     https://git.tartarus.org/simon/polyhedra.git
On the web:     https://git.tartarus.org/?p=simon/polyhedra.git
Branch updated: master
Committer:      Simon Tatham <anakin at pobox.com>
Date:           2019-07-08 19:19:21

commit 136fbc3731d40e6cd7a287391cfeef0a04f61c00
web diff https://git.tartarus.org/?p=simon/polyhedra.git;a=commitdiff;h=136fbc3731d40e6cd7a287391cfeef0a04f61c00;hp=99cc469a719677ce08d4f32535782dad5fc1ae63
Author: Simon Tatham <anakin at pobox.com>
Date:   Mon Jul 8 19:01:38 2019 +0100

    Migrate all these programs to use Python 'argparse'.

    It's my normal preference over getopt or manual argv-herding these
    days, partly because it's reasonably easy to add extra options, but
    mostly because it comes with --help built in, so every time I come
    back to this suite of programs after a few years' absence, I'll
    actually be able to remember how to use them without having to
    source-dive.

 canvas.py            |  28 +++----
 cleanpoly.py         |  45 +++++------
 describe.py          |  38 ++++-----
 drawnet.py           | 222 ++++++++++++++++++++++++---------------------------
 drawpoints.py        |  42 +++++-----
 drawpoly.py          |  63 ++++++---------
 dual.py              |  38 ++++-----
 flashpoly.py         |  37 ++++-----
 isometry.py          |  56 +++++--------
 mkpoints.py          |  41 ++++------
 nfaces.py            |  69 +++++++---------
 nvertices.py         |  39 ++++-----
 povpoly.py           | 117 ++++++++++++---------------
 regular/mkregular.py |  39 ++++-----
 untangle.py          |  30 +++----
 15 files changed, 393 insertions(+), 511 deletions(-)

commit 64fb3a6d3bd369fccfefeb96b2146eb8b8093b73
web diff https://git.tartarus.org/?p=simon/polyhedra.git;a=commitdiff;h=64fb3a6d3bd369fccfefeb96b2146eb8b8093b73;hp=136fbc3731d40e6cd7a287391cfeef0a04f61c00
Author: Simon Tatham <anakin at pobox.com>
Date:   Mon Jul 8 19:02:46 2019 +0100

    mkpoints.py: tidy up progress messages.

    Now each message overwrites the previous one, and also, we don't
    print them at all unless stderr is a terminal.

 mkpoints.py | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

commit bba236c7808252f45154f2c7a01a0aaec99a60e8
web diff https://git.tartarus.org/?p=simon/polyhedra.git;a=commitdiff;h=bba236c7808252f45154f2c7a01a0aaec99a60e8;hp=64fb3a6d3bd369fccfefeb96b2146eb8b8093b73
Author: Simon Tatham <anakin at pobox.com>
Date:   Mon Jul 8 19:03:06 2019 +0100

    cleanpoly.py: clean harder.

    The previous strategy was fine for merging two triangles across a
    common edge, but I had occasion to make it merge three or more
    coplanar around a central vertex, and it wasn't able to remove the
    last edge to that vertex and delete it. Now it can do that extra level
    of tidying.

 cleanpoly.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

commit f59ab63d0a1141285078b06bb9a9d25a5f698f44
web diff https://git.tartarus.org/?p=simon/polyhedra.git;a=commitdiff;h=f59ab63d0a1141285078b06bb9a9d25a5f698f44;hp=bba236c7808252f45154f2c7a01a0aaec99a60e8
Author: Simon Tatham <anakin at pobox.com>
Date:   Mon Jul 8 19:04:06 2019 +0100

    canvas.py: provide an HTML output mode.

    In this mode, instead of writing out just the raw JSON polyhedron data
    for embedding into an existing web page, we output a self-contained
    HTML document. Useful for initial testing and previewing.

 canvas.py | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

commit 2c2463509671d7b0df3a12bf7dfdcb7d35ec7e96
web diff https://git.tartarus.org/?p=simon/polyhedra.git;a=commitdiff;h=2c2463509671d7b0df3a12bf7dfdcb7d35ec7e96;hp=f59ab63d0a1141285078b06bb9a9d25a5f698f44
Author: Simon Tatham <anakin at pobox.com>
Date:   Mon Jul 8 19:08:09 2019 +0100

    mkpoints.py: add a projective mode.

    In this mode, opposite points on the unit sphere are identified with
    each other, by means of pretending each point's antipode is also
    exerting repelling force. Then at output time we can either print one
    element of each pair, or both.

    Printing both allows us to find widely-spaced point sets under the
    constraint that they're symmetric in central inversion; for example,
    where 8 unconstrained points buckled into a square antiprism instead
    of giving the vertices of a cube, 8 points under this constraint (or
    rather, 4 points plus their antipodes) do give a cube.

    Printing just one of each opposite pair is about to be useful for the
    script I'm going to add in the next commit.

 mkpoints.py | 45 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 13 deletions(-)

commit 8bdb8fe12a3396bf3ad88f828ef76faacf66c661
web diff https://git.tartarus.org/?p=simon/polyhedra.git;a=commitdiff;h=8bdb8fe12a3396bf3ad88f828ef76faacf66c661;hp=2c2463509671d7b0df3a12bf7dfdcb7d35ec7e96
Author: Simon Tatham <anakin at pobox.com>
Date:   Mon Jul 8 19:10:28 2019 +0100

    New script to construct zonohedra.

    A zonohedron is a convex polyhedron in which every face has twofold
    rotational symmetry, so that every edge has a parallel opposite edge
    on the far side of each face. This means that the edges come in
    equivalence classes all with the same length and direction (just start
    from any edge and keep jumping to the one opposite it on one of the
    neighbouring faces), and contracting all those edges to points
    generates a smaller solid with the same property, which inductively
    proves that the solid is actually _generated_ by its set of distinct
    edge vectors. Specifically, given a set of vectors, compute its power
    set; for each element of the power set, sum the vectors in it; then
    the convex hull of those 2^n points is the zonohedron.

    This tool generates one starting from a set of edge vectors. Because
    it's pointless to have two edge vectors be parallel, it's useful to
    use the projective mode of mkpoints.py without the --both option, to
    generate a good set of vectors as input to this tool.

    Unfortunately, it's beyond my usual level of numerical bodginess: if
    you give it a set of edge vectors that are too close to coplanar, or
    which have some nontrivial relation between them (e.g. the vectors
    from the centre to each vertex of an icosahedron), then it goes off
    the rails. To work around this I've added an option to perturb the
    input points just enough to avoid the problem, after which
    cleanpoly.py can clear up the mess. Horrible, but it works.

 zonohedron.py | 255 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 255 insertions(+)