Re: Bond Graph modeling with Dia

[Dave <spamless4 iasun2 epfl ch>]

Dolores Alia de Saravia wrote:

> I think there is another possibility. I attach two examples: zero.shape
> and component.shape which can be  starting points for better designs.
>
> For 0 or 1 junctions i think the simplest shapes as the one I send can 
> be enough. (with 0 and 1 "drawn" not written with characters; the 
> connection points are away... you dont need more gaps).
>  
I agree that your approach is a quick way to get bond graphs drawn out. 
The problems I see are:

1.    If I move your shapes around, the bonds may end up going across 
the top of the shapes.  The 'gap' enabled code is easier to work with, 
and bonds would never go across the shapes.  The 'gap' code is more 
general, and will be useful for other types of diagrams.  Dia will 
become the killer diagram editor :-).

2.    It may work okay to create printable diagrams, but if the goal is 
to parse the XML code to to create computer simulations as well, the 
parsing would be more difficult because of the multiple connections.  It 
would make more sense to have 1 connection for most bond graph elements 
(R,I,C,0,1,SF,SE,TF,GY) and to have 2 connections for modulated elements 
like the modulated transformer and modulated gyroscope (MTF, MGY). 
Well, maybe this would not be necessary since the incoming double arrow 
could be used to distinguish which incoming arrow is the signal and 
which ones are the bonds...but things would be cleaner and more general 
with gap code.  Elements would be simpler, and diagram editing would be 
easy.

3.    To avoid quickly having hundreds of different types of arrow 
heads, I believe that it is desirable to have a modular arrow head.  The 
code would be better.  But of course, it would be possible, for now, to 
simply add flat heads, flat heads combined with half arrows.  But I 
think that I have seen some bond graph work using half flat heads as 
well.  So it might be necessary to have half flat heads, full flat 
heads, half and full arrows with all combinations.  Bloat City here we come.

4.    Creating R,I,L,SS,SE,SF,MTF,MGY,0,1 elements with line art does 
not seem to be very reasonable.  Yes, it works.  But is it a good 
solution?  I don't think so.

The point in using Dia is to make things better than they are with xfig. 
I believe that gap code and modular arrows would also improve the 
quality of Dia as a general diagram editor.

Dave.