Kangaroo Grasshopper bending plates collision


(T Rosales Rodriguez) #1

Hi all!

I am new to Grasshopper and Kangaroo :slight_smile: I am trying to bend two plates by connecting the corners with cables and reducing their length. However, when doing this, the lower plate is pinching through the surface of the upper one. I think I should use the CollideMesh component but I am confused about its output (collide mesh). Could you please help me with this? Thanks in advance!!


(T Rosales Rodriguez) #2

I would also like to make hole in the mesh like in the Fukita pavillion in the picture. thaaaanks!


Do you have any code or geometry to work with?


(T Rosales Rodriguez) #4

yes, this is the code. thanks a lot!

20180125_bending sheet membrane 2.gh (63.1 KB)



I can’t know for sure but is there also some missing geometry in that file? (not internalized brep and/or points?)

I don’t have much of a clue how to use Kangaroo but have learned quite a bit trying to answer this question by adapting code posted two days ago by @DanielPiker in this thread:

I haven’t succeeded yet but I’ve learned one thing about Kangaroo that drives me mad! :rage: In my ignorance, I’ve apparently defined constraints that are impossible to resolve, so Kangaroo goes into an infinite loop and there is NOTHING I can do to regain control, short of closing Rhino. SO VERY ANNOYING!!!


Again, I am clueless about Kangaroo and can’t use your code (I have Kangaroo2 installed), so this probably won’t help. There are some bizarre hacks here to adapt @DanielPiker’s AnchorXY.gh example from the Force density thread, and the results aren’t pretty. See the purple group, for example, which culls the “naked points” around the hole edges to prevent them from being considered “anchors” and includes them instead in the “clothed points” to be moved, constrained only in X and Y while “floating” in Z.

Kangaroo doesn’t always adapt to changes upstream, so to speak, such as changing the Max Edge length slider (Custom Mesh Settings) of the original mesh, or changing the number of holes. It flails horribly in those cases until I close and re-open the GH file, though it does respond as expected to changing the Z depth slider. Amusing but not that impressive.

AnchorXY_2018Feb3d.gh (30.2 KB)

By the way, I did try anchoring only the corner points so the edges could sag too, like the pavilion picture, but the result looked bad. My two cents worth from the Kangaroo peanut gallery.


This won’t be news to experienced Kangaroo folk but the ‘Strength’ inputs of various components change things in noticeable ways. In Daniel’s original code, the Anchor strength was set to ten thousand, for example, whereas the code I posted had that reduced to only “10”. I didn’t notice the difference myself until after I posted, but it’s pretty obvious if you look at the edge points.

This version adds ‘Strength’ sliders to make it easier to see their effects:

AnchorXY_2018Feb3e.gh (32.2 KB)

NOTE: if you reduce Anchor strength to zero, the model dies and won’t recover without re-opening the file. :frowning:

(T Rosales Rodriguez) #8

Thanks a lot for your reply Joseph, was input was really useful! :pray::pray::pray:

(David S. Mavrov) #9

Something like this?

Mesh.3dm (144.4 KB)