[Ipe-discuss] Ipe features (was Congratulations !!!!)

[Johan Ingvast]

On Tue, 22 Feb 2005, Otfried Cheong wrote:
> Johan Ingvast wrote:
> 
> 
> > I'd like to suggest the standard arrow for metapost which works for most
> > curved lines.
> 
> Can you produce a path description of this arrow?  Or a few pictures?
The standard metapost arrow is somewhat different from what is common. It
is not a fixed arrow, but is built out of the path it should put the arrow
on.  A good picture of it can be found at the metapost homepage:
    http://cm.bell-labs.com/who/hobby/MetaPost.html
What metapost does is: From the path to put an arrow on cuts of the last
segment of lenght <ahlength>. Past this twice after having rotated it
around the tip an angle +-<ahangle>/2. The two short lines then makes up
the path for the arrowhead.
Here is an example of an metapost generated arrow next to an ipe-arrow.

<ipeselection>
<group matrix="1 0 0 1 41 55">
<path stroke="black" pen="0.4" cap="1" join="1">
27.0108 45.7507 m
26.4319 47.6436 25.7393 49.4087 24.9417 51.0035 c
22.2843 56.3193 18.6795 59.3064 14.92 59.3064 c
11.1604 59.3064 7.55569 56.3193 4.89822 51.0035 c
2.23984 45.6877 0.746753 38.4782 0.746753 30.96 c
0.746753 23.4417 2.23984 16.2322 4.89822 10.9164 c
7.55569 5.60059 11.1604 2.61353 14.92 2.61353 c
18.6795 2.61353 22.2843 5.60059 24.9417 10.9164 c
25.4734 11.9796 25.9584 13.1185 26.3943 14.3204 c
</path>
<path fill="black" fillrule="wind">
20.8566 1.27373 m
23.2192 3.02664 24.9757 6.27375 25.8723 10.6564 c
26.1106 11.821 26.2844 13.0466 26.3943 14.3204 c
25.6622 13.2722 24.8989 12.2977 24.1102 11.4083 c
21.1424 8.06111 17.9977 6.12725 15.0752 5.79048 c
</path>
<path stroke="black" pen="0.4" cap="1" join="1">
20.8566 1.27373 m
23.2192 3.02664 24.9757 6.27375 25.8723 10.6564 c
26.1106 11.821 26.2844 13.0466 26.3943 14.3204 c
25.6622 13.2722 24.8989 12.2977 24.1102 11.4083 c
21.1424 8.06111 17.9977 6.12725 15.0752 5.79048 c
20.8566 1.27373 l
h
</path>
</group>
<path stroke="black" matrix="1 0 0 1 108 53" pen="0.4" cap="1" join="1"
arrow="large">
27.0108 45.7507 m
26.4319 47.6436 25.7393 49.4087 24.9417 51.0035 c
22.2843 56.3193 18.6795 59.3064 14.92 59.3064 c
11.1604 59.3064 7.55569 56.3193 4.89822 51.0035 c
2.23984 45.6877 0.746753 38.4782 0.746753 30.96 c
0.746753 23.4417 2.23984 16.2322 4.89822 10.9164 c
7.55569 5.60059 11.1604 2.61353 14.92 2.61353 c
18.6795 2.61353 22.2843 5.60059 24.9417 10.9164 c
25.4734 11.9796 25.9584 13.1185 26.3943 14.3204 c
</path>
</ipeselection>


I guess there is a tool needed to generate this arrow that does not exist
at the moment; possibility to cut the line at a precice bowlength.
However the bowlenght can be changed to an intersection with a circle, if
that would be any easier.

/johan

-- 
Johan Ingvast, PhD student http://www.md.kth.se/~ingvast
Department of Machine Design, Royal Institute of Technology, Sweden
http://www.md.kth.se, http://www.md.kth.se/~cas	<--- Walking robot proj
tel +46 (0)8 790 95 36	mob. +46 (0)70 34 34 498