How to rotate a curve and generate multiple copies at once?

Hello,

I am writing to ask how to make multiple copies of a curve rotated about an axis.

I have just begun evaluating Rhino 5 and Grasshopper and have succeeded in generating a curve in the X-Y plane using a definition by Damien Alomar. I baked it, joined the segments in Rhino and have extruded it along the Z-axis.

I have succeeded in rotating a single copy in Rhino 5, but haven't yet found how to generate multiple copies.

I am very grateful for any assistance you can offer.

Thanks,

David

Attachments:

fibonacciSpiral_TDW_040415.zip, 36 KB

Replies to This Discussion

Permalink Reply by nikos tzar on April 6, 2015 at 5:12pm

Hello David,

If you want to create multiple copies you have to input multiple angles.

To create a list of multiple angles you could first create a domain (ex 0-360) and then a range of numbers in this domain ("divide" the domain to -let's say- 10 parts).

BUT you currently have 5 arcs and if you just plug them in like this, the first arc will be rotated by the first angle, the second with the second, etc. So you have two options:

1. you can join the arcs to a single curve which will then be rotated by all the angles, or

2. you can graft the list of arcs so that each one is in its own list (tree branch) and so is rotated by all the angles.

Permalink Reply by David Walden on April 6, 2015 at 5:24pm

Hello nikos tzar,

Thank you!

David

Permalink Reply by Daniel González Abalde on April 6, 2015 at 5:32pm

Just give several values, eg angle input of rotation, for various outcomes.

Add a simplification of the Fibonacci spiral def.

Attachments:

fibonacciSpiral_TDW_040415DGA.gh, 25 KB

Permalink Reply by David Walden on April 6, 2015 at 7:19pm

Thank you, Daniel!

Permalink Reply by David Walden on April 7, 2015 at 9:39am

Daniel, I will be using this to model the sunflower phyllotaxis. There will be 55 spirals CCW and 34 spirals CW.

As you can see, I've tweaked the definition you provided and copied and pasted the definition for the CW spirals. Can you tell me how to mirror the spirals about the Y-axis to get the spirals going CW? I tried modifying the vector and reversing values but I couldn't figure out how to get the spirals going CW.

Thank you

Attachments:

Attachments:

fibonacciSpiral_04_07_15_DGA.gh, 18 KB

Permalink Reply by Daniel González Abalde on April 7, 2015 at 10:22am

Well, I'm not sure what you are trying to do. I guess you try to get the mirror of each spiral, to try to make petals? If so, there are several problems. The spiral should only rotate 180 degrees, so that the mirror suits her, otherwise you will have an unwanted result (I guess). For a mirror, you need a plane, not a vector, but the problem is where to put the plane.
If I understand what you're trying to do, I think you are not following the correct logic. To perform the phyllotaxis I recommend you using distributed points rotating 137.5, instead of use fibonacci spiral.

Attachments:

fibonacciSpiral_TDW_040415DGA.gh, 25 KB

Permalink Reply by David Walden on April 7, 2015 at 11:10am

I was trying to generate a second set of spirals going clockwise instead of counter-clockwise.

If my understanding is correct, the intersections of those two sets of opposing spirals will result in another set of spirals. That is what I'm trying to model, eventually.

I know very little about components in Grasshopper aside from what I've learned in the last few days from the Getting Started tutorials by David Rutten.

Permalink Reply by nikos tzar on April 7, 2015 at 11:36am

Hello David, Daniel,

How about first mirroring the spiral and then rotating them both:

Attachments:

fibonacciSpiral_nt.gh, 22 KB

Permalink Reply by David Walden on April 7, 2015 at 12:17pm

Nikos, huge thanks! That helps immensely. Now I'll try to learn what all is going on in there!

Permalink Reply by nikos tzar on April 7, 2015 at 12:32pm

I just saw Daniel's approach with [polar array] instead of [rotate]. It is much simpler and easier to understand:

So we start with one CCW spiral,

we mirror it on YZ plane to get a CW spiral

and we do 2 polar arrays, one with 33 items and one with 52.

Permalink Reply by David Walden on April 7, 2015 at 2:03pm

This is awesome! How did you generate the message tags above the components I'm trying to implement Daniel's approach with [polar array]. This might take me a while.

Permalink Reply by nikos tzar on April 7, 2015 at 2:42pm

Select the components you want, middle click and select group