[Therion] scaling line ornamentation - metapost

[Bruce Mutton]

Hi

I'm wondering if there is a way to scale the size of line ornamentation with
the -scale option?

I am thinking about arrows (and map-connections) as in a previous post.

 

I notice that I can apply -scale to a line wall 

 

Eg 

line wall -scale xs

subtype debris

<list of coordinates>

endline

 

and the line will plot, but at always at normal scale.  I can see why that
might be, as there seems to be no way to pass the scale value into the
metapost definition of the wall (or arrow) line object.

However if I put in a layout.

 

min-symbol-scale m

 

then the wall (or arrow) that has a scale of s or xs will not plot (as I
think is expected). So there is some crude on/off control, but I have not
found where it is done.

 

So I am wondering, is there some way that we can have more refined control
of the scale of line ornamentation (wall debris, blocks, arrow heads)? 

 

I notice line arrow takes the special argument -head [both | none | begin].
Somewhere between the th2 file and the metapost arrow definition, the
argument -head gets changed to the variable Q that is parsed to the metapost
code, that controls which ends of the arrow line get arrow heads. I have
copied the code below.  Whereabouts is the code that tells Therion that
-head is parsed to the metapost definition as Q?

 

Bruce

 

 

In th2 file.

 

line arrow -head both

<coordinates>

endline

 

 

In thline.mp or in a layout file.

 

code metapost

% Q = 0 -- no arrows

%     1 -- end

%     2 -- begin

%     3 -- both

def l_arrow (expr P, Q) =

  T:=identity;

  pickup PenB;

  thdraw P;

  p := (-.1u,-.5u)--(0,0)--(.1u,-.5u)--cycle; 

  %          0.25 changed to .5 and close end to get nicer arrowhead

  if odd Q:

    thfilldraw p rotated (angle(thdir(P,0))+90) 

                             shifted (point 0 of P);

  fi;

  if Q>1:

    thfilldraw p rotated (angle(thdir(P,length P))-90) 

                 shifted (point infinity of P);

  fi;

enddef;

 

 

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