In the KeyframeEditor you can find the parameter attribute of a Simple Constraint.
By default the value of zero is installed in the keyframe at tick 0, and 1 in the keyframe at the end of the animation (default 99) or vice versa (1 at keyframe zero and 0 at keyframe 99)
This value describes the position of the constraint object on the curve; zero being at the start of the curve and 1 at the end. A value in between 0 and 1 places the object relative in between start and end.
When the curve is ‘closed’ start and end coincide. You can visualize the start/end of a closed curve by using the Rhino’s ShowEnds command (mark the Closed curve seams)
The direction of a closed curve can be monitored via the ShowDir command.
When the Constraint (to Path) is installed the commandline says : ”Select curve. Pick near starting end”. Then it depends on which side you click the curve whether the parameters are set 0 to 1 or 10 to 0. In your model you apparently click closer to the end.
But now… the constraint parameters in the KeyframeEditor can be edited. Please observe this model Angelo.3dm (46.6 KB) (It’s WIP 7).
Object 0 (the red circle) with parameters 0 and 1 behaves by default (the direction of the circle path is clockwise, the start/end is at 3 o’clock).
For object 1 (the blue circle) the parameters of keyframe 99 is set to 2. This makes it go round twice – a nice extra for closed curves.
Finally Object 2 (in green) is an example on how you can run your carousel. The parameters ranges from 0.25 to 1.25. Hence the object is shifted a quarter circle ahead of the red object 0.
I leave the mathematics necessary for your carrousel barges to yourself.