[Therion] How to use user-defined symbols
Martin Sluka
martinsluka at mac.com
Sun Feb 2 23:06:21 CET 2014
Bill,
There are two kinds of symbols in Therion - first one are symbols which are included to Therion in time of compilation - like symbol "stalagmite". Second kind are user symbols. The definition of user symbol should be like:
def u_p_stalagmaflat_AMER (expr pos,theta,sc,al) =
In XTherion you call it as:
point u:stalagmaflat_AMER
Red are symbols which definition is not known.
M.
Odesláno z iPhonu
2. 2. 2014 v 22:00, Bill Gee <bgee at campercaver.net>:
> Hello everyone -
>
> I have been struggling for the last several days trying to figure out how to
> build and use my own symbols. I need a symbol for two kinds of formations -
> Stalactiflats and Stalagmaflats. These are basically stalagmites which are fat
> (several feet diameter) and flat on top like a table (or flat on the bottom).
>
> It appears there are two problems to solve. The first, which I address in this
> question, is how to get xTherion to use a custom symbol. The second is to
> figure out how to draw the symbol in Metapost. For now I am ignoring the
> second problem. One step at a time!
>
> After spending several hours going through Therion By Example, I was able to
> get a custom symbol to work, but only by replacing an existing symbol. I used
> the NSS "gradient point" example.
>
> Changing the Metapost code as shown does not produce any error messages.
> However, it also does not produce a symbol in the PDF output. All I get is a
> red dot.
>
> ===============
> code metapost
>
> def p_stalagmaflat_AMER (expr pos,theta,sc,al) =
> U:=(.15u, .4u);
> T:=identity aligned al rotated theta scaled sc shifted pos;
> pickup PenC;
>
> #Left Hand side
> thdraw (-.3u, -.2u) -- (-.7u, .1u);
> thdraw (-.2u, -.1u) -- (-.4u, .6u);
>
> #Centerline
> thdraw (0u, 0u) -- (0u, .9u);
>
> #Right side
> thdraw (.3u, -.2u) -- (.7u, .1u);
> thdraw (.2u, -.1u) -- (.4u, .6u);
>
> enddef;
>
> initsymbol ("p_stalagmaflat_AMER");
>
> endcode
> ==================
>
> Since I am not replacing an existing symbol, I leave out the "symbol-assign"
> line.
>
> In xTherion I try to use this by inserting a point of type "u" and adding an
> option "-subtype stalagmaflat".
>
> I think this is where I am missing something ... How to call the custom
> symbol with a "u" point. Is this the right syntax?
>
> In the worst case I suppose I could set it up to replace a symbol that I won't
> use for this cave - a ladder, for example. That would probably cause quite a
> bit of confusion down the road, so I would much prefer to avoid it.
>
> I am using Therion 5.3.13 on 64-bit Fedora 20.
>
> Thanks - Bill Gee
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