Kangaroo's Rod not recognizing circle

Hello everyone

I’m trying to make a bending active structure where the circle in the middle of the rectangle would be some sort of ring, but I can’t seem to get Kangaroo to recognize the circle as when I turn on BouncySolver, the peak of the structure would instead be the lines that make up the square around the circle.

A few lines also appear as seen on the picture below, and I have a feeling those are the lines trimmed by the circle.

There are also 4 points inside the circle that somehow act as an anchor for the mesh. Thing is, I have no idea how to get rid of the points and I wasn’t even trying to work with meshes to begin with, but somehow BouncySolver automatically generated it.

Any help would be greatly appreciated. I also would like to apologize in advance should you find my definition messy. You can ignore everything on the right of BouncySolver as I’m still trying to focus on getting the form finding right.
Thank you very much
Test.gh (31.7 KB)

Hi @rehpq,

Can you describe what is the result you are after?
I’m confused by the use of the rod component for the internal edges of the mesh.
Is this to be a gridshell (the grid resists bending, like it is made of timber), or a tensile structure, with only the boundaries resisting bending?

If the aim is to keep the internal boundary circular, then you can either pull the points to a target curve, or if you want to use bending, then you’ll need a polyline (not a NURBS curve) connecting the points at that boundary.

Hello Daniel,

Thank you for replying. Yes, it’s going to be a gridshell, which is why I’m confused as to why Bouncy solver generated a mesh even though I was only going to work with the lines.

I actually missed the part where I was supposed to determine how the circle’s going to behave. If I were to pull the points to the curve, how do I go about doing that exactly? I assumed I should use the Curve Pull component from Kangaroo but I don’t think I know how to use the output.

As for having the circle bend as well, I tried to connect the points with polyline, but the order of the points wouldn’t let me make a circle. Is it possible to fix that?

Once again, thank you very much.


I managed to make the polyline (still have no idea how to use Curve Pull component) but the 4 points in the center are still present and the trimmed lines still sort of stand vertically instead of curving like the rest of the grid.

Test.gh (27.9 KB)

All of the U force is being concentrated to the points along the opening, so there isn’t much constraining the little segments that connect that polyline to the rest of them.
You could try a separate bending force through the opening polyline, sort of like what you’re doing with the outer boundary … you could also add a Line goal here to add some control / pull it in a bit further to better match the curvature. Also, maybe try distributing the U force throughout the entire set of inner polyline points.

I’m a bit confused about how you’re setting up your line segments for bending though - these don’t act like long, continuous timber lathes in two directions … in any case, here’s a hopefully helpful hack to illustrate the above.

Test_v2.gh (43.8 KB)


Thank you very much Nick!

1 Like