How to move like finger

Hello,

I've started to use grasshopper a couple days ago, and I thought what I wanted to do was easy (it may still be so). I want to be able to create two connecting lines in Rhino, then using grasshopper make the lines move in a finger-like fashion using two sliders (one for each line). I was able to get the first line moving using the Rotate3D component, but it's harder to get the second line to rotate as its center of revolution keeps changing (it's the end point of the first line). How can I do this?

Replies to This Discussion

Permalink Reply by Ethan Gross on July 25, 2016 at 12:45am

Hi Ibrahim, here is a different approach - whether you like it or not. Rather than compound several rotations, I first defined an allowable range of motion for the end of the finger (Radius = finger length) and then specified the point at which the finger is directed. This defines two circles, one from the tip of the smaller joint and one from the base of the larger joint. Their intersection is two points, one of which I chose to be the "knuckle". The base, knuckle and tip are then used to construct a polyline.

Attachments:

finger.gh, 15 KB

Permalink Reply by Ibrahim Mahmoud on July 27, 2016 at 5:31pm

Oh wow that's more complicated than I thought, but it still works and I like that, thanks!

Permalink Reply by Daniel González Abalde on July 25, 2016 at 3:48am

Just apply the transformation of the first line to the second.

Attachments:

finger.gh, 23 KB

Permalink Reply by Joseph Oster on July 25, 2016 at 10:37am

I like this very simple version by Daniel, which I simplified a bit further:

'Crv' contains two curves (lines), end-to-end. The plane that these two curves are in is assumed to be 'World XY', which is why the 'Unit Z' vector works as an axis.