[Therion] Shortening long passages in extended elevations

[Tarquin Wilton-Jones]

Hi all,

With extended elevations, you might want to show only the most important
parts, like pitches, while showing long passages as a shorter distance
with a break symbol. Imagine a cave with an initial pitch, a long
passage, and a final pitch, where the extended elevation should
concentrate on the detail of the pitches only, and not have the long
passage wasting space. For a real example, see this rigging topo:

https://cncc.org.uk/caving/topos/download-single.php?id=6

If the passage is horizontal, you could easily achieve this by setting
the legs of the long passage to "extend vertical", so that its stations
to not take up any horizontal length. You can then manually draw the gap
with some lines.

However, if the long passage slopes downwards, this will make the two
parts of the passage break with a vertical gap between them. This makes
sense because it means that the extended elevation will show the
vertical range of the cave, which is great if that's what you are hoping
for. But in a rigging topo, it is less useful. There is no equivalent
that I can see to "extend equate 21 57", which would be an equate that
happens only during an extended elevation. Essentially, this is the
desired outcome though.

For a real example, see this rigging topo - the breaks represent a
passage that has lost as much as 20 metres of altitude, which is
completely ignored:

https://cncc.org.uk/caving/topos/download-single.php?id=61

One method I can think of - but it feels like a hack - is to draw the
upper pitch in one map, and the lower pitch in another map, then use map
offsets to pull the lower map into the desired position when rendering.

Does anyone have a better solution to this? Can "extend hide" do
something useful or will that still keep any vertical (and horizontal)
offsets?

Thanks for any advice.

Tarquin