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1. Re: Pen tool and open objects: only center align stroke?
Teri_P Oct 26, 2010 10:36 PM (in response to El Gu man)Gustavo,
Yes, this is normal behavior for the Inside/Outside Stroke options.
The reason is that there is no unambiguous definition of what the "inside" and "outside" of an open path are.
A. The most natural interpretation is the "inside" is the same area that gets filled when you apply a fill color to an open path, namely the region that would be on the the inside if you were to join the two endpoints. However, if used for the stroke, this would cause the stroke to flip from one side to the other when the path crossed that virtual connection line (consider a S or N shape), and it is problematic defining how the stroke behaves at the crossing region. Do you clip the stroke to the area that would be filled, or do you allow it to extend beyond that region?
B. Another interpretation (I believe this is the one used by InDesign) is that the "inside" is always on the same side of the path as you travel along it, with the side being chosen as whichever side has the most of the fill area. For straight lines (which have no fillable area) or for paths where both sides have equal fillable areas, it would have to use a tie-breaker such as always on the left as you travel from start to endpoint, or always on the right.
C. Another interpretation is to treat "inside" and "outside" very loosely, so that one of them is reinterpreted to mean the left side (in path walking order) and the other is interpreted to mean the right side.
The second two interpretations have the advantage that the half-stroke never flips from one side to the other, but they both have the disadvantage that they do not coincide with the interpretation of inside/outside used for closed paths, and hence as you draw along making a new path, the stroke could change dramatically when you close the path, especially for self-intersecting paths such as figure 8's. Of the latter two interpretations, B has the advantage that for most common paths such as U or L shapes it coincides with the filled area, but the disadvantage that on paths that switch curvature like S and M, changing the shape of the path can cause the stroke to suddenly reverse which side it is one. C has the opposite tradeoffs - the stroke won't flip side unless you do something that reverses the whole path direction, but the stroked side of the path would bear no relationship to the filled area, which makes the wording "inside" and "outside" seem odd.
It would certainly be possible to pick some interpretation and just go with it, but whichever one was picked, there are kinds of paths where most users would prefer one of the other interpretations. For each option, I'm sure many users would interpret the disadvantages inherent in that choice as bugs.
HOWEVER...
If you are using CS5, you can use the Beautiful Strokes feature to apply a stroke that has 0 width on one side of the path and all the width on the other. This allows you to have one-sided strokes on open paths, and avoids all the issues and ambiguities above, since Beautiful Strokes explicitly treat all non-centered strokes as having a left side and a right side, regardless of whether they are open or closed.
P.S. I lived in Santa Fe (De Vargas Junior High) in 1967-1968, and in Nambe (Pojoaque High) from 1969-1972.
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2. Re: Pen tool and open objects: only center align stroke?
El Gu man Oct 27, 2010 6:35 AM (in response to Teri_P)Hi Teri,
Thanks very much for the very thourough explanation. I found what the problem was.
I had try to draw an irregular shaped open path with the pen tool. I then reflected it (to make it exactly the same) and joined it at its ends in Pathfinder. I then wanted to add a new stroke (Appearance panel). Before I added a new stroke, I "knifed" a section of it (to make room for another element), which made it an open path again, with all its "consequences"...as you so well explained.
Gustavo
PS: Great to hear you lived in "Santa". I came in 1985 (a long time ago), originally from Uruguay (South America), and never left it.
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3. Re: Pen tool and open objects: only center align stroke?
Kurt Gold Oct 27, 2010 11:37 AM (in response to El Gu man)Gustavo,
it's still not obvious which version of Illustrator you are using. However, have you already considered creating either Art brushes or Pattern brushes to get the inside/outside appearance on open paths related to their path directions?
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4. Re: Pen tool and open objects: only center align stroke?
El Gu man Oct 27, 2010 3:29 PM (in response to Kurt Gold)Hi Kurt,
Good point! . I've got CS5 (CS4 too). Haven't played with making a customized brush. Can you set up two different colors, do you know?
Best,
Gustavo
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5. Re: Pen tool and open objects: only center align stroke?
Teri_P Oct 27, 2010 10:31 PM (in response to El Gu man)You can use as many colors as you want in an Art, Pattern or Scatter brush definition. (A Calligraphic brush can only be one color.)
You can also layer multiple strokes using the Add New Stroke button on the Appearance panel.
A good way to see what can be done with Brushes is explore the Pattern Swatch Libraries that ship with the product.
Similarly, you can explore the preset Graphic Style Libraries for examples of multi-stroke art styles.
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6. Re: Pen tool and open objects: only center align stroke?
El Gu man Oct 28, 2010 6:44 AM (in response to Teri_P)Thanks, Teri. I've created some patterns in the past (they never came out correctly "joined", as it seems to be the challenge). Patterns and brushes in Illustrator are areas I should explore in more detail.
Watch out, I'm gonna send you some chile verde .
Best,
Gustavo


