[artworks] Unpredictable control point behaviour
- From: Simon Smith <simon_smith@xxxxxxxxx>
- To: artworks@xxxxxxxxxxxxx
- Date: Wed, 21 Feb 2007 20:35:55 GMT
Hi
I'm noticing some inconsistent behaviour when trying to manually shorten the
lines in the linked artworks file. http://www.simon-smith.org/Artworks.zip
(note capital letter in URL.)
My method has been to zoom in to 4000%, select the desired line segment,
then select the Curve tool and click slightly inside the line length at each
end, thus adding two extra control points to each line. Then I delete the
two outermost control points, thereby slightly shortening the line without
otherwise distorting it.
This works fine about 75-90% of the time. (See Screen2.) The other 10-25% of
the time, clicking near the end control point creates the startpoint of a
brand new line, which is not what I want. (See Screen3.) If the grid is
turned on, the new control point may appear some distance away from where
you clicked, especially at high zoom values. Usually you can work around
this by clicking progressively further away (Screen4) until Artworks decides
what you really want and obliges.
Sometimes reversing the path order will get Artworks to behave as expected,
and let you place the new control point closer to where you originally
wanted it.
Sometimes Artworks decides you want to extend the line, not shorten it, and
you get a sort of 'sharp tick'. Depending on the angle and curve of the
line, it may align neatly enough with what you have already drawn that you
don't notice. Other times the shape of the outline will change enough
that you can tell something funny has happened. Other times the line will
'jump' slightly from its original position, spoiling the smooth overlap that
you originally had. The fix is to undo and retry by clicking in
slightly different positions until the program does what you want it to.
While these 'bugs' are most noticeable at very high zoom factors, I have
encountered them at view sizes in the 100-400% range as well.
Can anyone explain what is going on here? Why does Artworks sometimes let
you modify the control points of an existing line, other times insist on
starting a new line for you? Is it a genuine bug, or a subtletly of the UI
that I have failed to grasp? I find the current behaviour quite annoying,
and I would like to avoid triggering it if possible.
When working on the Celtic knot in the linked file, sometimes when I
shortened the white lines I would have chanced to process the ends in the
same order that they were originally drawn, other times I would have done
them in the opposite order.
Original line: A----------------B
Original line cut at C and D: A---C------D-----B
Making C------D
Or A---D------C-----B
Making D------C
Line CD trimmed in turn: C-E--F-D
Making E--F
Or C-F--E-D
Making F--E
Or D-E--F-C
Making E--F
Or D-F--E-C
F--E
I'm wondering if the order of processing might be making a difference,
because by the time you get to the E-F stage there are four different
possible combinations - and one in four gives 25%, roughly corresponding to
the error rate I've been getting.
I also have some comments/suggestions to make about the control point user
interface, which I will put in a separate email.
Simon Smith
--
Have you heard of the International Obfuscated Perl Code Competition? Each
contestant is shown ten Perl programs - five that have been written normally
and five that have been deliberately obfuscated. In order to win, you just
have to decide which is which.
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