Re: [artworks] Odd bounding boxes
- From: Martin Wuerthner <lists@xxxxxxxxxxxxxxx>
- To: artworks@xxxxxxxxxxxxx
- Date: Mon, 26 Mar 2007 20:56:11 +0200
In message <27ce4bc84e.zen44412@xxxxxxxxx>
Simon Smith <simon_smith@xxxxxxxxx> wrote:
> [instructions to construct the difference of shapes using intersection...]
>
> A.) Where the box cut the ellipses there are several control points slightly
> to one side of where the 'cuts' were made. Now, these are straight even
> though the rest of the curve is a proper curve. Why is this?
Intersection does not necessarily produce the minimal number of nodes.
In particular, as you have observed, it sometimes adds an extra node
close to points where shapes intersected. The result is visually
correct despite the small number of extra nodes.
> Furthermore - and this is the annoying bit - converting the unwanted
> straight line sections back to curves is fiddly because there are
> several control points exactly overlapping.
I do not think so - they are not exactly overlapping. You just need to
zoom in a bit and they separate visually.
> Some visual feedback when there are multiple overlapping control
> points would be very useful, and a way to step through them one at a
> time without disturbing them would also be welcome.
Yes, that sounds like a nice idea anyway. For instance, the cursor
keys are currently unused in the Line/Shape tool. They could shift the
control point selection one anchor point forwards/backwards in the
shape (so with just one point selected you could step through all of
them individually).
> B.) Experimentation with selecting the two surviving shapes shows that
> somehow ArtWorks still seems to retain a memory of the shapes' original
> 'bounding box'. I can drag a selection box over one shape and yet the other
> shape is the one selected. Confusing. The bounding area seems to be that
> of the large box drawn in stage 6, so the behaviour is more apparent if you
> make this box much larger than necessary. The spurious bounding box seems to
> disappear if you move the shape, but I'm not entirely sure I have fully
> understood ArtWorks' behaviour here. If one can have excessively large
> bounding boxes, as here, I would like some way to be able to see where they
> are - or else I would assume this behaviour needs to be treated as a bug and
> corrected.
First of all, you can see the bounding box of any shape by selecting
the "bounding box tool" - I mean the perspective tool. It shows a red
box, which is precisely the selection's bounding box, i.e., what
ArtWorks currently thinks it is. Yes, in this case the "break shapes"
operation has apprently failed to update the bounding box. I have
added this to the bug list. As you noticed, just moving the shape
fixes it, so it should not be a big issue. Besides, a bounding box
that is too large does not cause any significant problems (except for
the inability to select the object by dragging a box closely around
it), whereas a bounding box that is too small causes redraw problems.
> C.) While the procedure of drawing boxes and intersecting does allows one to
> split and join shapes however one pleases, it does introduce several extra
> manipulation stages. Would it be easy to add 'union' and 'difference'
> facilities that automate the procedures given in the Intersect5 and
> Intersect6 tutorials? I would like be able to construct shapes by starting
> with a series of unions, then difference bits away, then add on some more
> using union, then subtract some more, and so on. While logically equivalent,
> using a series of Intersects doesn't come nearly as easily to me.
Well, it would not be too hard, but you should not be surprised to
learn that that has already been suggested 10 years ago, right after
the Intersect tool and the Tutorial were first published. I just never
got round to adding it. Of course, it would be nicer to have all the
boolean operations but the point is that you can do it, albeit with a
bit of extra work, while there are many other feature requests for
things that cannot be done at the moment.
Martin
--
---------------------------------------------------------------------
Martin Wuerthner MW Software lists@xxxxxxxxxxxxxxx
---------------------------------------------------------------------
Other related posts:
- » Re: [artworks] Odd bounding boxes
