Constraint to a Crv

Hi Joshua,
I’m back from my holiday and I started testing the latest Wip8.

I see a vast improvement since the July version and this is great!

I missed the constraint to a curve, the ability to keep a point "on Curve". I know this exists on Kangaroo so I hope it wouldn’t be so hard to implement it in the Contrastints.
due to the way the IK is implemented it could be used to solve conceptual mechanisms (linkage) and having the option to keep a point on a crv could help to simulate the rotation (like in a train rod).


Hi Riccardo,

Hope you had a nice holiday. Glad to hear that you’re happy with the direction constraints are heading as well.

Allowing the point on line and point along line constraint to generalize to other curves is on the roadmap and I hope to get to it soon. I’m currently doing some background work to handle it. The issue is logged here if you want to keep up with it.

Are you mainly looking for these curves to be static in the constraints sketch? Or do you want the solver to actually move the control points of a NURBS curve?

It would also be nice to see some examples models you’ve been working on, assuming you can share. I’m trying to identify pain points as well as any situations we cannot currently handle with constraints in its current form.


Hi @Joshua_Kennedy,
I’m fooling around with it, not yet a real example but what came into my mind is that because the engine is Kangaroo I can use the constraint also as a mechanism solver.
In the picture below there’s the example I was trying:

The left-most line is anchored to the origin point, the circle has a fixed radius and position.
If I can like the horizontal line to the circle I can make a kind of piston and rod simulation.

My goal, for now, isn’t to have a full simulation of a working mechanism (that should be done in Bongo3) but still being able to create a conceptual mechanism and modify the sketch position would help a lot in the early stage of mechanism design.
For example, this can apply to a cabinet door movement, to any hinge for product lids, foldable chairs, and so on.

*I solved it by attaching a line from the circle center to the le horizontal line endpoint and controlling the angle but is way less intuitive.