Shift List & Reassign

Hi,

I am a novice to Grasshopper and currently trying to get my head around it.

I have some queries if any one is willing to help me out please.

In the file (3dm + gh) that I have attached is a tube with holes drilled in it. When I was experimenting with Grasshopper, the holes do not flow and connect the way I intended. I'm not sure how to reassign them to look similar to the image below. I would like to keep the staggered pattern that has been created in Grasshopper, but have the blend look more like the image below. The side view should only have horizontal lines (no diagonal ones like the ones in the gh file) as if the tunnels were drilled directly to the center, but the interior pattern was shifted to create the (top view) "S" curve. The image below (a) was modeled in Rhino and illustrates the basic concept. I have been informed that you can shift holes or shift items in a list with the 'Shift List' component, but I do not know how to integrate that into the definition to move the interior holes.

Best,

Daniel

Replies to This Discussion

Permalink Reply by Dedackelzucht on February 28, 2013 at 2:35am

huhaa, what a good mornig exercise :-)

I made 2 defenitions. The fist one is up to your questions. The secound is about some random fun :-)

Best Regards

DeDackel

Attachments:

roatingWorm_DeDackel.gh, 48 KB

Permalink Reply by David Stasiuk on February 28, 2013 at 2:50am

Without being able to play with your definition, I see a few potential issues. I'm not sure if the way you're dividing your surfaces is duplicating points along the shared seam...generally when you divide a surface you have to extract either the first or the last item, because they are spatially identical. Also, when you shift, you will then want to set "wrap" to true. This way the last item in your list doesn't get shifted out of existence.

But perhaps a simpler approach to the whole thing would be to simply rotate your outer surface around a plane or axis at the center, and not bother with shifting values. This would also give you more control of the relationship between the circular perforations. Also, instead of the blend curve, you could evaluate each surface at the connection points and use both the points and tangent values to feed the interpolate (t) component.

In this example I'm using the add-ins lunchbox for the diagrid component and mesh pipe for the curved tubes.

Permalink Reply by Dedackelzucht on February 28, 2013 at 2:54am

yes with lunchbox its much easier to archive...nice solution

Best Regards

DeDackel

Permalink Reply by David Stasiuk on February 28, 2013 at 3:34am

nice!

Permalink Reply by Dedackelzucht on February 28, 2013 at 3:38am

the other way around looks funny as well

Permalink Reply by Daniel Chang on February 28, 2013 at 9:13am

Hi Dedackelzucht,

Thanks for the prompt reply.

It looks like you are having a blast. In your models, the direction of the blend curves seem to be erratic and overlap at some points (which is not ideal). Is there a way to make them more uniform and symmetrical (like David's)?

A file would be much appreciated!

Thanks,

Daniel

Permalink Reply by Daniel Chang on February 28, 2013 at 9:04am

Hi David,

Thanks for the prompt reply! Here is my definition. Can I have a copy of your's to play with?

Where can I get lunchbox and what makes it so appropriate for this project?

To my knowledge, there aren't any duplicating points along a seam. Rotating the outer surface around an axis at the center is precisely what I need! Just curious -- what is the advantage of your alternative to blend curve. I'm fond of blend curve because of it's and symmetry and simplicity with the ability to change the bulge factor with one slider. All I need is that natural bend that accurately follows the twist.

Thanks,

Daniel

Attachments:

twist.gh, 6 KB
twist.3dmbak, 56 KB

Permalink Reply by David Stasiuk on February 28, 2013 at 9:25am

Here you go. You can find lunchbox on food4rhino...It's just that Lunchbox has a really efficient means to extract diagrid node points from a surface. Plus it has all sorts of other useful tools in it. Highly recommended!

Honestly, I haven't used blend curve all that much, so if you are more used to it by all means you should use it. Using the interpolated curves with the surface tangents is useful because it achieves the same natural meeting points. But like anything with gh, there are endless ways to reach your goal.

Attachments:

grid_rotate.gh, 7 KB

Permalink Reply by Daniel Chang on February 28, 2013 at 7:32pm

Thanks!

I downloaded the Lunchbox installer, walked through the instructions, and seem to have it successfully installed after restarting. I don't know if this is related to Lunchbox, but it seems that "mesh pipe" is missing. Do I have to install something else?

Best,

Daniel

Permalink Reply by David Stasiuk on March 1, 2013 at 12:54am

oops :) sorry about that: http://www.grasshopper3d.com/forum/topics/mesh-pipe

Of course you can always use the regular pipe if what you're looking for in the end is brep/nurbs geometry...meshing is much lighter but behaves very differently.

Permalink Reply by Daniel Chang on March 1, 2013 at 11:49pm

Thanks!

I ended up using the regular pipe.

My design now has a slight adjustment. The tube is tapered from one end to the other (attached). This will be 1-2 mm at most.

I have drawn an exaggerated taper to show that I would like the channels to follow in "steps" so that they do not change in angle (the drawing is a side/front section view). How do I reference the tapered surface in that manner?