Fw: Re: Problem with survex

[Olly Betts]

On Mon, Dec 05, 2011 at 03:47:57PM +0000, Wookey wrote:
> "R. Winkler" <winkler at gss-tuebingen.de> wrote:
> > It seems, that I worked out the problem.
> > It occur, when an flags splay is in the datas as below:
> > *begin
> > *flags splay
> > 0    1    10.40    -27    60
> > *end

I created a .svx file with this in, processed it, ran extend on it, and
loaded the resulting .3d file into aven, and didn't get the error.

> > without that, all worked as usual.
> > Did it never happened before?
> 
> No, but you do seem to have found a genuine bug. Olly has already
> taken a look and an example minimal survex and/or 3d file that causes
> the problem will be very welcome.

Yes, or even a non-minimal .svx file would be fine - I can chop it down
easily enough myself to create a minimal example.

> Creating a 3d file that contains a tube with only one cross-section in
> it is not allowed. Cavern will never do this, but apparently extend3d
> will. 

My initial guess was that extend was breaking the tube where it broke
the loop, and that could create a tube with a single cross-section,
but in fact it just copies the tube structure as-is (which is a bug
really).

Aven should probably just discard or handle such degenerate tubes, but
it would be interesting to find out how/where they are coming from as
they shouldn't occur in files produced by Survex programs.

Cheers,
    Olly