[Therion] Symbol for fixed ladder

25 Jan 2017

      This post from January 2014 explains the rectangle with number of steps specified.
https://www.mail-archive.com/therion@speleo.sk/msg04814.html

Bruce

-----Original Message-----
From: Therion [mailto:therion-bounces@speleo.sk] On Behalf Of Martin Sluka via Therion
Sent: Wednesday, 25 January 2017 7:45 PM
To: List for Therion users <therion@speleo.sk>
Cc: Martin Sluka <martinsluka@mac.com>
Subject: Re: [Therion] Symbol for fixed ladder

Isn't there one on wiki? The principle was to draw rectangle and to add the parameter as number of steps. 

Odesláno z iPhonu

24. 1. 2017 v 23:51, Benedikt Hallinger via Therion <therion@speleo.sk>:
...
Hello,
i get gray hair with metapost while i want to make a line symbol for ladders, so i can nicely draw them in my maps as the cave have alot of them.
The basic idea i had was, t define a symbol of one "rung" segment 
(rung and a little of either sides, like the letter "H") as a symbol picture. Then i wanted to apply this image seamlessly over the length of the given path (straight lines) What i have for now is the following, however it does not show at all (still shows a red line with symbol set AUT in effect), so i have no clue how to even debug this.
I tried to start with the example from thbook salted a little with peeks to the internal metapost codes.
Can someone assist please?
Thank you very much!
# Symbol for fixed ladder
   def l_fixedladder_SKBB (expr P) =
     T:=identity;
     cas := 0;
     dlzka := arclength P;
     mojkrok:=adjust_step(dlzka, 1.0u);
pickup PenC;
     sideL := (-.20u,0)--(-.20u,0.20u);
     sideR := (.20u,0)--(.20u,0.20u);
     rung  := (-.20u,0.10u)--(.20u,0.10u);
picture symbol,test_symbol;
     symbol:= image (
                thdraw sideL;
                thdraw sideR;
                thdraw rung;
                );
forever:
           t := arctime cas of P;
           thdraw symbol shifted (point t of P) withcolor black;
           cas := cas + mojkrok;
           exitif cas > dlzka + (mojkrok / 3); % for rounding errors
     endfor;
enddef;
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[Therion] Symbol for fixed ladder

Bruce Mutton