[Therion] Hiding small objects at large scales

[Thomas Holder]

Hi Bruce,

>      % label with minimum text height condition
>      vardef p_label@#(expr txt,pos,rot,mode) =
>        if abs(llcorner txt - ulcorner txt) > 5pt:
>          p_label_orig@#(txt,pos,rot,mode)
>        fi;
>      enddef;
> 
> Thomas
> The above does not seem to work.  It seems likely to me that the third to
> last line is missing a ; although adding it does not seem to help that much.

no, the semicolon is not necessary here.

> The definition p_label_orig does not seem familiar to me.  The data.mp file
> produced by Therion does not contain one of that name, only a p_label.
> In the above code I changed p_label_orig to p_label (assuming recursive
> definitions might be OK), but I get an error,
>>> p_label_orig.lft
> ! Isolated expression.

recursion on the original p_label definition is not possible, it just 
gets overwritten. So you need to carry the complete label code when 
overwriting it, what I did with introducing p_label_orig (you could put 
it all in the p_label definition, but I tried to separate new code from 
existing one for clarity).

> culminating in "can't open file" and no pdf output.

uhm, now it gets crude. I haven't looked in detail into the code, but a 
quick inspection led me to this hack:

     vardef p_label@#(expr txt,pos,rot,mode) =
       if abs(llcorner txt - ulcorner txt) > 5pt:
         p_label_orig@#(txt,pos,rot,mode)
       else:
         last_write := charcode
       fi;
     enddef;

Has to do with the temporary file written by write_circ_bbox, which 
might not be created if the label gets skipped.

> The differences between what you posted and what I have been using are...
> 
> code metapost
>   fonts_setup(6,8,10,12,16)
> 
> instead of...
>      % set xs and s to 1pt
>      verbatimtex
>        \def\thsmallsize{\size[1]}
>        \def\thtinysize{\size[1]}
>      etex

looks good, I just forgot that there was a fonts_setup method ;-)

> I did not define my own p_label_orig (because I assumed the default must
> already be defined somewhere).  If I do define as per your entire example I
> get different, and perhaps less serious errors, "can't open file" and still
> no output...

see above. In any case you need the p_label_orig.

Cheers,
   Thomas