The scenario:

I have a large cave, and so to gain better control of extent of pages for export than is possible using atlas, I define and export sub-maps.  Each submap (of maps) is a logical grouping of passages in part of the cave, each submap either linearly placed one after the other, or above and below other groupings of passages.

ie map AllofCave

              map Submap1

              map submap2

              map submap3 etc

endmap AllofCave

Each of these submaps contains small local maps that are offset and previewed above and or below.  ie a short bit of passage here and there.

To facilitate flexibility of map production, the thconfig selections are grouped and mostly commented like this…

              # select AllofCave

              select Submap1

              select Submap2

              # select Submap3 etc

In order that each of these submaps can be presented as a stand-alone output showing its relationship with the neighbouring submaps, or even all of the cave, each submap contains previews of its neighbouring submaps.

ie

map Submap1

              preview above Submap2

              preview above Submap3

              <other ‘map of maps’ specified to define this part of cave>

              <including small local map [offset] above or below>

endmap Submap1

map Submap2

              preview above (or below) Submap1

              preview above Submap3

              <other ‘map of maps’ specified to define this part of cave>

              <including small local map [offset] above or below>

endmap Submap2

Usually in the thconfig, one of the selects is uncommented at a time, but in parts of the cave and for some end uses, two or three submap selects are uncommented, as with Submap1 and Submap2 above.  This is when the problem arises.

The problem:

Having two or more selects for the same projection breaks the previews of the small offset sections of passage in the second and subsequently selected submaps.

ie

Submap1 and Submap3 previews are correct, but all of Submap2 offset previews forced to above by the preview spec in Submap1

The order of selecting Submap1 and Submap2 has been swapped, so you can see previews in the top part of the image are now correct, but the previews in the bottom part of the image are incorrect.

Possible Workaround:

Use only ONE select (for each projection) by collecting all of the maps you want to ‘select’ into a new map.  The disadvantage of this is that one must pre-empt all combinations of submaps into yet more maps.  But anyway, lets try it.

Now the individual passage offset previews are correctly rendered in all of the submaps (Submap1 and Submap2), except that the other submap previews (Submap3 etc) are not rendered at all.  So that did not work.

Trying adding -map-level 1 to the select for the new map gives some insight, but not a solution…

…because now the behaviour is the same as if I had uncommented multiple selects in the thconfig file and not defined a new map at all.

The workaround/solution I came up with:

The submap previews in the submaps specified after the first one will be ignored (somehow they are in a different map-level, but the first one is not), so any submap previews that are wanted must be specified directly in the new map.

ie

map newMap

              preview above Submap3

Submap1

Submap2

endmap newMap

Now all of the offset previews and submap previews are displayed as they ‘should’ be displayed.

Question:

The Therion Book on page 50 seems to hint at the workaround/solution I eventually came up with.

Why can the above output not be achieved by specifying multiple selects in the thconfig?  Or can it be achieved?  It would be a simpler solution than having to define a map for each of the many combinations of submaps that users might want to produce.

I realise I don’t understand ‘map-level’ very well.  Does anyone have any insights beyond what is written in the Therion Book and in the wiki?

Bruce