[artworks] Anchor points and symmetry [was: Re: Ideas for new version]
- From: Martin Wuerthner <lists@xxxxxxxxxxxxxxx>
- To: artworks@xxxxxxxxxxxxx
- Date: Wed, 10 Jan 2007 14:14:27 +0100
In message <4ea2fbeed7gav@xxxxxxxxxxxxxxxxxxxx>
Gavin Crawford <gav@xxxxxxxxxxxxxxxxxxxx> wrote:
> A feature that would be really good is the ability to align selected
> nodes - in a similar way as the Alignment dialogue allows with objects.
Yes, this has been mentioned before and is a very worthwhile feature,
but it is surprisingly tricky to achieve because moving an anchor
point is a very complex operation in ArtWorks (as opposed to Draw).
This is caused by the unique feature of "smooth" anchor points in
ArtWorks. Anchor points are set to be "smooth" by default, so ArtWorks
keeps the curve smooth when they are moved, which means the control
points of neighbouring anchor points are adjusted.
By the way: Anchor points do not have to be smooth, they can be set to
"sharp" in the path editing tool (in which case they behave like in
Draw). This feature is so intuitive that most users probably miss it
altogether, but go back to Draw and edit a path with several curves
and you will notice what you are missing. ;-)
So, moving several points in one go by different amounts (which is
what aligning would do) is a bit tricky, but I will probably have a
look at it because I spent some time manually aligning anchor points
yesterday and that was really tedious. Currently, the only way to do
it is to open the Path info box, read the coordinate of the anchor
point, select the other anchor point and manually enter the coordinate
there.
Actually, what I was really doing was to create a symmetric shape, and
I actually find myself having to doing this surprisingly often. So
often that I am thinking of adding some support for symmetry. Aligning
anchor points would solve part of the problem, but you need to align
the control points, too, and there is no way to add a function to do
that because control points cannot be selected. Besides, for symmetric
shapes you would have to move the control points in the opposite way
in one direction and align them in the other.
So, what I want to do is add support for automating the complete
process of creating a symmetric shape and of redoing the symmetry
after one half has been edited. At the same time I want to support
having a symmetric part of a shape without the whole shape having to
be symmetric (imagine drawing a silhouette of a rooftop with an
elaborate chimney - the chimney itself is symmetric in itself but the
overall shape of the silhouette may not be, e.g., if the chimney is
not in the middle of the rooftop).
The difficult bit as always is telling the program what you want,
i.e., which part of the shape should be adapted and where the symmetry
axis is. I would like to do all this using the existing user
interface, i.e., by selecting anchor points, so I cannot really see
any way to specify an arbitrary axis. However, most symmetry will be
for a vertical or horizontal axis anyway (and if any other is
required, the shape can be rotated first by the user). So, we can
define the axis by using an anchor point plus the information about
the direction of the axis coming from the fact whether the "horizontal
symmetry" or the "vertical symmetry" button is used.
It would then work as follows: You draw the shape including the first
half of the symmetric part. You select the first anchor point of the
part that is to be mirrored, then you select the anchor point at the
end of the curve where the mirroring should take place - that anchor
point defines the symmetry axis. Then you click on the horizontal or
vertical symmetry button and the remaining half of the symmetric part
is created.
So far so good, but sooner or later you are likely to want to edit the
shape. After editing one half of the symmetric part you can force the
other half to be updated by selecting the anchor point that starts the
edited part, the anchor point on the axis and the anchor point that
ends the mirrored part that is to be updated. Then you click on the
symmetry button and the second half is updated.
Does that make any sense?
Martin
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Martin Wuerthner MW Software lists@xxxxxxxxxxxxxxx
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