[Therion] maps off solves unexpected scrap stacking order where no maps are defined

[Bruce Mutton]

This is just a FYI in case anyone is interested.

A problem solved, but a mystery not solved.

 

On and off through 2019 there were discussions about how to predict or debug
scrap stacking order.

This message by Tarquin covers the expected behaviour fairly
comprehensively.
https://www.mail-archive.com/therion@speleo.sk/msg07925.html

 

That is all very well, and 99% of the time my projects stack scraps the way
I expect.  Except that I have one large project where lower passage scraps
stack on top of upper level scraps, in a few locations only, in the scenario
where no maps defined whatsoever (with the intention that scraps therefore
stack according to average altitude).  Other scenarios using the same source
data, where maps are defined and selected, all plot as expected according to
the map structures.  But for large overview maps I need to plot all scraps
without any map structure, and I'd like them to stack correctly.

 

The offending scraps were drawn many years ago, and were all much longer and
encompassing much greater passage height variations than I would adopt these
days.  I just assumed that the average heights that Therion calculated were
somehow not collated in the stacking order that I expected.  Anyway I
eventually found the time to check the scrap and heights reported in
therion.log.  To my slight surprise I found that in fact the average heights
that Therion calculated were in exactly the order I expected.  So why was
Therion not stacking the scraps in the expected order?  My anticipated
solution of breaking the scraps into pieces to make them behave properly no
longer seemed likely to make any difference.

 

Since it was implemented, I have been making use of the 'maps off' to
disable previews and offsets, as a more refined way of achieving a
particular output than just 'not defining' any maps in a particular
thconfig.

https://www.mail-archive.com/therion@speleo.sk/msg07571.html 

 

In desperation I thought I'd try adding 'maps off' to the thconfig above,
where no maps were defined.  It should, I expected, make no difference at
all.

And in one easy step, all of the scraps now plot in the correct stacking
order!

So why does 'maps off' make scraps plot in the correct order when there are
no maps defined?

 

Bruce

 

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