Connecting center points of a mesh grid

Replies to This Discussion

Permalink Reply by Daniel González Abalde on July 10, 2016 at 12:44am

If you have Weaverbird (and you should have it) you can use the dual graph algorithm (wbDual). But if you want to do it from scratch, you can use SandBox to know the faces connected to the not naked vertices.

Permalink Reply by Tim Chen on July 12, 2016 at 1:01am

Thanks Daniel, wbDual works, though it requires the initial quads to find the dual, and not just the points. I will look into the SandBox thing!

Permalink Reply by Daniel González Abalde on July 12, 2016 at 4:20am

If you have a grid of points, you can have a mesh using [Mesh From Points] component. If you want to work with topology, using meshes will make things easier.

Permalink Reply by ng5 Alex on July 10, 2016 at 6:35am

another solution could be the following

best

alex

Permalink Reply by Joseph Oster on July 10, 2016 at 9:30am

Well, that's very interesting - I know nothing about meshes.  But your result doesn't match the list of square Polyline Curves in his "What I want to get" example.

GH code would have been nice, even for an example this simple.

Permalink Reply by Tim Chen on July 12, 2016 at 1:03am

Thanks alex, I realized my sample def does contain only a rectilinear grid. Delaunay would actually triangulate any other grid, no?

Permalink Reply by Joseph Oster on July 10, 2016 at 9:20am

Here's something that works for different rectangular surfaces.

The yellow group discovers the U/V "dimensions" of the mesh (I have no clue what determines them?), which are then used (-1) as inputs for 'Divide' domain, which goes to 'SubSrf (Isotrim)'.  The edges of the sub-surfaces are joined to create the polyline curve for each grid square.

The sequence of the list of resulting Polyline Curves is top-to-bottom, then left-to-right, while the sequence of your "What I want to get" list is left-to-right, then top-to-bottom...

Attachments:

• mesh_grid_2016July10a.gh, 28 KB

Permalink Reply by Joseph Oster on July 10, 2016 at 10:18am

Hey, this works pretty well - and thanks to some sorting of center points, the list of resulting Polyline Curves is in the same sequence as your "What I want to get" list: left-to-right, then top-to-bottom.

re-posted to hide point sorting

Attachments:

• mesh_grid_2016July10b.gh, 20 KB

Permalink Reply by Tim Chen on July 12, 2016 at 1:18am

Thanks Joseph, your def works fantastically for flat surfaces.

Though, I've attached an updated definition, adding two non-flat surfaces to it. One is a hypar, the other is a hemisphere. With the hemisphere, there's the additional question of how to connect the triangles at the apex.

Attachments:

• mesh_grid_2016July10b_tim.gh, 20 KB

Permalink Reply by Hyungsoo Kim on July 12, 2016 at 5:04am

Hi.

Let me try mine. As Daniel already mentioned above, Weaverbird's dual graph is definitely the simplest way.

And to me, this will fit well into "Relative Item" case.

Check attached. Best.

Attachments:

• mesh_grid_2016July10b_tim_reV2.gh, 26 KB

Permalink Reply by mark zirinsky on July 12, 2016 at 6:18am

Nice one, M. Kim. Elegant use of tree partition, path manipulation and tree relative item components

Permalink Reply by Tim Chen on July 13, 2016 at 3:22am

Thanks for the algorithm Kim! Works fantastically.

But of course I have more questions!

In the case that the initial mesh is not a square with equal number of U and V, how do you partition it differently? For example, with the dome, you manually supplied 18 as the number, but if you are given a mesh, how would you automatically find the "dual".

Thanks! Tim