[Therion] Extended elevation control - Embedded image does not appear in some layouts

[Benedikt Hallinger]

I really feel, we need a "true" way of specifying how to hide/select 
things for various outputs.
Some kind of optional selector attribute inherent to any symbol, without 
affecting or misuing the other settings.
This cuold also be used to hide/select symbols based on scale (which is 
currently kind-of-supported by using the symbol size - which I cannot 
use beause I need that for actual sizing of stuff).

A quick Idea could be:
1. untagged elements are always printed

2. tagged elements only if they are selected in the thconfig

3. actual systematic is user-defined, so we have maximum flexibility.
For example, I could imagine mixing several systematics, one for desired 
output scale and another for special purposes:

--------- thconfig --------
select tag scale:250
select tag scale:500
select tag remarks
select tag crossSections:abc
export map ....
---------------------------
In the th2's I just tag the items with "-tag scale:500" or "-tag 
crossSections:abc" (or both).
This would completely (and optionally) decouple the show/hide from 
internal magic and support various usecases out of the box. One just 
needs to think of a good tagging systematic for his usecases/dataset.




Am 2025-02-19 17:29, schrieb Andrew Atkinson:
> On 19/02/2025 15:58, Bill Gee wrote:
>> I would also like a way to produce a map which has SOME (not all) 
>> cross- sections.  Right now it is all or nothing.  You either get 
>> every cross- section or you get no cross-sections.  This might be done 
>> by using PDF layers and letting the cross-section scrap specify the 
>> layer it goes on.
> 
> You can sort of do this with
> -attr <name> <value>. <name>
> Then use this in metapost
> 
> p36 thbook
> You can test presence of such a variable using if known ATTR_<name>: 
> ... fi.
> 
> However, my metapost was not good enough and I kept getting bugs. So I 
> used python to pull them out, then removed the ones I wanted. I thought 
> I had put the code online, but cannot find it!
> 
> However, the use of attr would work better if symbol-hide worked for 
> it. Unfortunately I do not think that it does.
> 
> You could abuse the system by abusing the -context option and setting 
> it to a symbol you do not use then turn that off with symbol-hide.
> 
> 
> Andrew
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