[Therion] Placing part of a map below another

[Bruce Mutton]

>> Break will not work in map definition from maps. Only sequence of particular maps works. 

 

>OK, now how come I didn't know that?!

 

>Whenever I make maps, I have been putting "break" in there, and it has happened to work because I will always put them in the right order anyway. It doesn't show any error message, and just silently ignores them. (It doesn't hurt to have it there, if only just to help mental understanding of the layers.)

 

>But even the Therion book does it - see the "displaying overlaying maps in offset" section. When defining "break" it doesn't say that it applies only to scraps and not maps. And when defining "map" syntax, it actually shows you putting a map reference, then "break" then another map reference.

 

>This should really be stated very explicitly, since it is not at all consistent with what the book shows. Are you sure it's not a bug?

 

>I was told previously that maps represent their scraps, so a map that references two maps could just be thought of as the combined list of scraps (and breaks) within them. But as you said, it seems to implicitly add a "break" at the end of each child map.

 

>Could someone authoritatively state the intended behaviour here, because either a bug needs to be fixed, or the documentation needs to be updated to match the implementation. I will happily file the required bug report accordingly.

 

>Cheers :)

>Tarquin

_______________________________________________

 

Hi Tarquin

Don't worry, it took me 12 years to discover that break was completely ineffective for maps that contain maps!

 

Last month Stacho announced a new 'maps [on]off' feature https://www.mail-archive.com/therion@speleo.sk/msg07571.html

It adds some more reporting to the therion.log, that includes map definitions and elevations.  Is quite informative, but as yet quite buggy, or else it is showing up some hither to unnoticed problem with  my datasets.  Current issues include altitudes reported as an overflow value if a scrap is empty, and if a map is defined from maps or includes a map defined from a survey centreline.  Also ‘maps off’ takes 4x longer to compile and produces pdfs 15x larger.  Is a problem as ‘maps off’ is a nice way to disable offsets and cross-sections for overview maps. I mention ‘maps’ as it is indirectly related to ‘break’. It provides useful insights, and warrants a wiki article once its behaviour settles down.

 

I'm certainly not authoritative, but I think the ‘break’ behaviour is, and is intended to be, as follows;

•             Breaks are required for maps defined from scraps if you want one set of scraps to render over another.

•             Breaks are not required for maps defined from maps (as there is an automatic break inferred by Therion between every map in the definition).

•             However a break placed in a map defined from maps will not cause any error. It is perhaps useful for the map author to use a break to clarify how main levels of cave are subdivided.

•             Items at the top of a map definition list are taken to be the highest level passages, and render over top of items below, regardless of their average elevation based on centreline stations.

 

The 10 June commit on Github appears to correct some of the issues in the Therion Book that you mention, but for some reason they don’t seem to have turned up in the latest version that I downloaded.  The issue is with the documentation I think.

 

Bruce

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