[Therion] Splays - Revisiting Breaking extended elevations

[Tarquin Wilton-Jones]

> And I assumed that if I placed the extends in-line, the splays would
> behave.  I am not sure though, as I have not carried out any explicit tests.

Sadly not. Therion - in all cases - extends the splays in the same
direction as the default direction from that station (or wherever you
placed the inline extend command). Basically, the splays act like legs.

This is really quite useless when you are trying to draw the passage
shape correctly.

TopoDroid, Pocket Topo and Survex all extend only the legs. They all
keep the splays in the "same" direction (relative to the leg) as they
were before, which makes them normally perfect for drawing extended
elevations. They can project forwards and backwards out of the page (so
to speak), so they end up the right distance, visually, from the station.

There is always the issue when you are at a station where the extend
direction changes from left to right or vertical, since at that point
you don't know whether a splay should take its direction from the leg
before or the leg after (or the "nearest" leg to it - perhaps the most
useful answer). Survex gets this wrong sometimes, but is normally useful.

Even so, that issue is just peanuts compared with how difficult it
currently is to use Therion's exported XVI to draw your extended
elevations. I would take an odd splay being wrong over *all* splays
being wrong any day.

Virtual awards await anyone who chooses to attack this problem.

Tarquin