Re: Rounded Polyline, and other questions?

[anthonym overture com]

Okay, here's the patch against the HEAD.  Let me know if there are any
changes people might like.  As for moving some things to geometry,
specifically I'm talking about the somewhat general point_cross, dot2,
line_coef, line_to_point, and point_perp.  Although the fillet function
could also arguably be there or not.

The algorithm was taken from one of the Graphics Gems books, all of
whose code is in the public domain (as stated in the book), you can
find all the code from the books here

http://www.acm.org/tog/GraphicsGems/

There are lots of 2D algorithms for all sorts of interesting geometrical
problems in the series, some of which may be useful to others.  I've
definately found it useful.

Anyway, let me know if some changes should be made to the patch.  Also
let me know if I missed anything in it.

-Anthony

On Wed, Jun 16, 2004 at 07:00:23AM +0200, Cyrille Chepelov wrote:
> Le Tue, Jun 15, 2004, Ã  10:50:36AM -0700, anthonym overture com a écrit:
> > Wow, its been a while since I posted this, but I've been super busy with
> > other stuff.  Anyway, last night I finished a first pass at adding
> > rounded corners to zigzaglines and polylines, by adding some code to
> > the diarenderer.  I was developing against the DIA_0_94_DEV tag, should
> > I post patches against that, or against the HEAD?  Also, I'd be interested
> > once I post it in knowing whether some of the added functions should make
> > their way into the geometry.* files.
> 
> geometry.* ? Oh. Probably, let's have a look at the code!
> 
> > Anyway, if someone could let me know which is the current tag to submit
> > patches against I'll post it.
> 
> HEAD.
> 
> 	-- Cyrille
> 	
> > 
> > -Anthony
> > 
> > On Wed, Apr 28, 2004 at 10:44:47AM +0200, Cyrille Chepelov wrote:
> > > 
> > > Le Mon, Apr 26, 2004, Ã  02:32:28PM -0700, anthonym overture com a écrit:
> > > 
> > > >   Now I'm working on the sequence and message flows which are essentially
> > > > zigzaglines with a certain subset of arrows.  One difference however is
> > > > that in the BPMN docs, the flows use orthogonal connections with rounded
> > > > corners, and I would like to mimic this.
> > > > 
> > > >   I've looked the the current crop of programmed objects and found that
> > > > the SADT arrow does this, but this object seems to rely on a new orth
> > > > connection object which is claimed to be a short term object.
> > > > The SADT arrow also seems to not include some of the code in the
> > > > zigzagline which pushes the line behind the arrow point (behavior I like
> > > > because it makes the arrow heads look nicer).
> > > 
> > > Indeed. SADT was one of my first dips into dia, and it hasn't
> > > benefited from some subsequent waves of refactoring. In particular, not
> > > only it does not push the line end behind the arrow point like most
> > > other objects do, but I think it also lacks autorouting and
> > > autodirection.
> > > 
> > > The approach you outlined seems like a good plan (especially with the
> > > default renderer in place), and I'm looking forwards to seeing it. If
> > > you have the time to refactor and port SADT arrow over to the new code
> > > (beware the automatic colouring), my gratitude will be proportional to
> > > the number of SADT-specific line you delete, at constant feature set ;-)
> > > 
> > > 
> > > 
> > > >   Now I have a couple of questions.  Is the above a feasible approach?
> > > > Are there any recommendations on different approaches?  Should I
> > > > implement a rounded corner dialog into the zigzagline, such that
> > > > the corner rounding works the way it does with the box (ie, you have
> > > > an option to set a corner radius, if it's zero don't round and use
> > > > the old functions if it is greater than zero use the rounded methods)?
> > > 
> > > It could be a simple extra property (for poly_conn and orth_conn). In
> > > fact, that was my original approach, which Alex shot down in favour of
> > > diagram type-specific objects (and with the experience since then, I'd
> > > say he was totally right with respect to user-visible objects, though
> > > I'd say the question of whether to make PolyConn and OrthConn aware of
> > > the concept of corner radii, or to extract RoundedPolyConn and
> > > RoundedOrthConn out of a blend of Poly/OrthConn and "SADT - Arrow" could
> > > be a subject to debate. I'd say that the former approach may be better
> > > today, if it can be done without creating a lot of mess in the code. As
> > > this seems to affect only the rendering and perhaps the mouse hit code
> > > in the case corner_radius > 1e-3, it may be a good thing to add a
> > > (hidden, unsaved) corner_radius field to these base classes, which can
> > > be declared as the storage place for properties in your new objects if
> > > they need (and statically reinitialised to SADT's current corner
> > > radius). Later if users want it in the generic zig-zag and ortho line
> > > objects, the property can be exposed there.
> > > 
> > > >   I'm really new to the code so could be completely off on all of the
> > > > above, please correct me if I am.
> > > 
> > > I think I agree with Lars' reply to this paragraph: welcome on board!
> > > 
> > > 	-- Cyrille
> > > 
> > > -- 
> > > _______________________________________________
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> > > Main page at http://www.lysator.liu.se/~alla/dia
> > > 
> > 
> > -- 
> > ------------------------------------------------------------------------
> > Anthony Molinaro                                 <anthonym overture com>
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> > Main page at http://www.gnome.org/projects/dia
> > 
> 
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-- 
------------------------------------------------------------------------
Anthony Molinaro                                 <anthonym overture com>

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