Grasshopper

algorithmic modeling for Rhino

Can CurvePointCollide (CPC) be set to function bi-directionally as can be done with SurfacePointCollide (SPC)?

Hi all,

similar to my previous experimentations, I am trying to recreate the effect of bendy puffy interactions but now in 2D. CurvePointCollide seems to be lacking the bi-directionality of its bigger brother SurfacePointCollide. Is there any way to make the points influence the shape of the input curve? 
Is this function hidden/unobtainable/planned?


Thank you,

Greg

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Replies to This Discussion

Hi Greg,

In the current release there is Collide2d for interaction between pairs of closed polylines in plane.

I also have working and will include in a coming release sphere-cylinder and cylinder-cylinder collisions like in Kangaroo1.

These can be used for point-line and line-line collisions with a thickness.

True point-line collisions are problematic because there isn't a defined inside/outside. The proper way to deal with this would be to use continuous collision detection, where you actually detect collisions in space-time rather than just instantaneous snapshots of space. It has some advantages, such as preventing 'tunnelling' where fast moving objects pass through each other with the discrete time-step, but it also significantly complicates the whole process. I'm not sure at the moment if the advantages would be worth the development this would require, but am open to ideas on this.

Thank you for this Daniel,

I'll try those options... however SurfacePointCollide does work a treat in 3D. I may then create a closed 3D mesh but operate on and constrain to a single plane (or very thing 3D slice). That way I can make use of the volume function but effectively project it all onto a 2D plane. A closed body for pneumatic cushions makes sense and so I don' mind using that.

I have a few questions that I hope you don't mind me asking you next week. One of which will be: how is the volume function working and how does it relate the volume value to node loads (or vectors). I'd love to discuss this with you some more.

Peace,

G

For example... see attached file.

I've gotten this to work very well with fully 3D meshes... but this routine crashes when adding the beam (data sets 0:1 and 0:2 at the Kangaroo input). The beam works on its own, as does the "2D" cushion.

I wonder if it is something to do with tolerances or perhaps shape mesh angles or perhaps the fact that I define length constraints further upstream than the definition of the final mesh input for the SPC component.

I'd appreciate any tips!

Many thanks,


Greg

Attachments:

Hi Greg,

This is what I get when I connect those inputs in your definition:

Are you seeing different behaviour?

How odd!

That's exactly the behaviour I was expecting... but on my computer Kangaroo goes red and complains of "at least one error occurred"... 

1. Solution exception:Mindestens ein Fehler ist aufgetreten.

How strange... and you didn't change a thing?

Hi Greg,

I did change something in the Kangaroo build to fix a bug in the volume component. I just wanted to confirm that this was the cause, thanks.

I'll try and get a release with this fix in out ASAP

Oh yes please!!

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