[Therion] Slope symbol needed

[Stacho Mudrak]

> Yes I suppose so. Possibly only point gradient and line slope. I don't
> really understand what the difference between line gradient and line slope is?

Line gradient is a simple arrow. Line slope defines in fact an area and 
should draw a lot of arrows perpendicular to the given line.

>> In any case, we should probably create BCRA symbol set in standard therion
>> distribution. We will try...
> 
> That would be nmarvellous. I've just downloaded JD Hobby's metpost book, and
> read the relevant section of the thbook but it all looks rather scary. A way
> to create new symbols with something mere mortals can understand, like SVG
> would be nice, although I can see that SVG->metpost is probably not possible. 

I have also huge problems with metapost, but drawing simple symbols is 
really easy, when you just modify existing ones. There are just two 
important commands:

thdraw - which draws a path
thfill - which fills a path with color

and path is defined like: (X1,Y1) -- (X2, Y2) .. (X3,Y3) .. cycle
-- means straight line
.. means some sort of spline
cycle (not neaded) means that path is closed

With this, you are able to draw most of the symbols. Some lines or area 
symbols are more complicated, but I think that basic things in metapost 
are not more complicated than in SVG.

Regards, S.