Thank you Maren and Brynn for the suggestions, I've been playing around with a few things...
The Scatter extension seems to be the best compromise at the moment (more on that in a bit).
The Markers approach was at first very intriguing, but without the ability to restrict the length of the path as it's being changed, I think it's more trouble than it's worth. Using a straight line with 2 nodes and the Add Nodes extension, I was able to get a path containing the exact number of nodes I wanted evenly distributed along the path, but then moving that straight line into the curved path turned out to be too much work. It's much easier just to draw the rough shape of the curve to begin with, then tweak it into the correct shape.
The alternative would be to create the rough path first, then evenly distribute the required number of nodes along that path. I sort of got this to work using Add Nodes and adding by "Segment Length" rather than "Number of Segments". But, it was trial and error to figure out the correct "Maximum segment length" in order to get the correct number of nodes. The result did evenly distribute the nodes along the path.
If I used "Number of Segments", then I could get the correct number of nodes, but they weren't evenly distributed along the path. It seems to add the number of nodes you specify between each of the segments. So then I tried the Align and Distribute dialog, but it only seems to allow you to distribute horizontally or vertically, but not along the entire length of the path -- ie, so the distance between the nodes is the same all along the curved path.
The other problem was, I could never get any object I created to show up as a Marker. When I select the object, then "Object->Objects to Marker", the object would disappear, but it wouldn't show up in the Stroke Style Markers drop downs. I could see it was there by looking at the XML, but never could see it in the drop downs.
At any rate (at least for the moment), I've given up on the Markers approach.
So on to the Scatter approach. First off "Scatter???" -- seems a very odd name for this extension. It brings to mind randomness or chaos, when in fact "Scatter" seems much more orderly and consistent than "Pattern along Path".
Good news is, it does work better for my purposes than Pattern along Path. At least with respect to the distortion of the circles. ie, with Scatter the circles are NOT distorted. I still have the same trial and error problem in order to get the correct number of objects on the path -- adjusting the "Space between copies" and/or tweaking the curve of my path to make it slightly longer or shorter.
The other advantage of Scatter compared to Pattern along Path is that after the objects have been distributed, they all seem to be in one group. So a simple ungroup means I can tweak the position of any of the objects. With Pattern along Path on the other hand, once the objects are on the path it seems to be a series of groups and not as easy to get back to the copies of the original object.
The downside to Scatter is related to something I hadn't mentioned. Originally, I said my path was just a series of circles. Well, that was mostly correct, in truth my path is a series of 5 circles followed by an oval, then 5 circles, an oval, etc. So when I was using PAP, I created a group containing 5 circles each separated by a small gap, then the oval. PAP nicely distributed this along the path, making sure to curve the entire group so it matches the path. Of course the obvious problem with PAP is that the circles and oval then became distorted.
If I try to use Scatter with this group (5 circles, 1 oval), then the group isn't curved, so I end up with a straight line pattern going along the path... not what I wanted. If I use just a single circle then Scatter works fine and I can go in after the fact and replace every 6th circle with the oval and that's not too bad.
It seems like the option in Scatter "If pattern is a group, pick group members" and "Pick group members Sequentially" should do what I want, but it doesn't work quite right, or I couldn't get it to work. It does alternate between the group members, but it inserts a large gap between each of the group members. The gap between the last member and going back to the first member seems to be the "Space between copies" value, but the gap between each of the group members is much larger and no apparent way to change it.
To test, I created the following:
- simple path (15 nodes that curves around a bit). - small 25px diameter solid blue circle with "1" in the middle - made that into a group of it's own. - second 25px circle with "2" in the middle, into a group. - grouped the 2 numbered circles together. - opened Scatter with the 2 circle group and the curved path. - used 5 for the "Space between copies" and then Preview.
What I see is the #1 circle is set at the start of the path, followed by a large gap, then the #2 circle. Then a small gap equal to the "Space between copies value of "5" and the #1 circle, large gap #2, small gap #1, large gap #2, small gap #1, etc.
If I add a #3 circle, it works the same:
- #1, large gap, #2, large gap, #3, small gap, - #1, large gap, #2, large gap, #3, small gap, - #1, large gap, #2, large gap, #3, small gap, - etc
Maybe that's the way it's supposed to work, but it doesn't seem right to me. Seems like the gap along the path should be the same for all the objects in the group.