ARRAY WITH OBJECTS OFFSET FROM PATH

[Colin-Pearson]

Hello World.  I'd like to array some objects along a path, but I want 2 rows of objects offset to either side of the selected path.   Is this possible?

My task is to array along a line which is tangent to 2 circles of different diameter.  These circles live in a dynamic Block which uses a Stretch Action to let the user move them away/towards each other.  I originally tried this with Tangent Constraints, but the result of using the stretch was that the lines did not change length, the whole block just moved, not just one circle stretching away from the other.  So my thought was to draw a single line connecting the centers of the circles and use an array which is "centered" on the path.  I the offset was equal to the radius, then the lines would be tangent to the circles.  (This is kind of a work-around b/c for this to work, I have to fudge the circles so they're both the same diameter.  The original idea is still my favorite anyway, but I don't know how to get the lines to stretch with the double tangency Constraints I had on them.)

[Libbya · Accepted solution]

If the objects are drawn offset from a line that is used as a path, the arrayed objects will all be offset from the path.  

[Colin-Pearson]

WHY DID I NOT THINK OF THAT??!?  I had the idea in my head and was looking for some property of an array that could offset from the path.  Of course all you have to do is start with the geometry you want and it works like a charm.  Thank you!

[Colin-Pearson]

@Libbya  could you please identify the odd behavior shown in the screencast?  If I stretch the block downwards, the array behaves as intended.  However, if I then stretch it back upwards, the array (and path) does not change length and gets 'pushed' along.

7176de3d-9461-4417-83cd-947dd3bc550b,640,620

[Colin-Pearson]

dwg attached

[Colin-Pearson]

attaching screencast again.  Edited my previous post and now I don't see it up here.

 

[Libbya]

You're pointing out why I generally avoid the use of constraints.  They are inconsistent in their behavior.  It is sometimes possible to make their behavior more consistent (e.g. make the array path endpoints coincident to the circle) but often times there is not a consistent solution.  

[Colin-Pearson]

Well, at least if I understand their limitations, I can try to avoid them in situations where they may be problematic.  Thanks for the input.

[Colin-Pearson]

@Libbya I'd love to ask if you could help me identify the source(s) of weirdness, if you have the time and inclination that is.  There's a couple things happening that I don't understand.

1) The stretch Action applied to the Linear Parameter called "HEADROOM" has a minimum value of 29.9" set.  I can drag the block out long, then drag it back short and it works fine.  If I drag it past the 29.9", it stops there at the minimum as intended.  However, if I TYPE a value for HEADROOM, then most of the block moves and leaves the two loops of chain on the left side floating in space.  The actual separation of the endpoint of the HEADROOM parameter is correct, even though it gets weird when you type a value in for HEADROOM.  It almost like the value HEADROOM value is displayed in the drawing, but the Stretch doesn't get applied to the Polylines that serve as the paths for my arrays (if that makes any sense).  

2) The grip for the Linear Parameter called "HEADROOM" and the grip for one of the Rotate Parameters (the one situated below the bottom hook) sometime get moved.  Dragging the block longer/shorter is okay.  However, if I first rotate the block, then drag it, the HEADROOM grip gets moved off of where I'd like it to be.  Interestingly, if I rotate the block by TYPING an angle into the Properties, this behavior doesn't seem to happen.  If you switch the Lookups to the 0-0-0 state you'll get the side view of this contraption.  I think the issue I just described is showing up in this view as well.  In the 0-0-0 (side) view, the lower hook and chain get skewed if you drag them via Stretch Action if you have already rotated the block by using the Rotate grip.  If you type a rotation degree into the Properties, the lower hook and chain Stretch/drag as desired.

3) Here I just have a question.  The Stretch Action selection set makes me crazy - I don't understand why you have to always re-pick your Selection Frame.  Is there a way to set this to keep the Selection Frame and only need to Add and/or Remove objects from the selection set?  If not, is there a way to always show the previous Selection Frame?  Mine is there sometimes and I can select the exact same frame by snapping to the corners, but other times the previous Selection Frame is not shown.

Huge thanks for your patient help thus far.  No worries if you don't feel like looking at this anymore, I wouldn't blame ya!  Have a great day.