Connecting Points, Newbie

Hello everybody,

maybe my question is very simple but I hope you can help me.

First I have a lot of 2D random points, connect them by using delaunay (edge). So I get triangles.

Now, there is my problem. I try to get the center points from each of these triangles. Then I would like to connect the corner points with the center points to subdivide my triangles.

I hope you can help me.

Greetings

Phil

Replies to This Discussion

Permalink Reply by Damon on July 3, 2014 at 6:21am

This might work for you. I don't work with meshes very often, so the thing that hung me up for a second was getting the Mesh Explode. I tried Deconstruct Mesh and Disjoint Mesh first. Hope this helps get you to the next step.

Attachments:

DelaunayMeshCenters.gh, 7 KB

Permalink Reply by nikos tzar on July 3, 2014 at 6:40am

It really depends on what you need to do next.

for example, this definition creates the lines you need but it doesn't actually divide the mesh faces.

Attachments:

subdivide.gh, 9 KB

Permalink Reply by Philipp S on July 3, 2014 at 7:27am

Thank you very much for your answers.

In generell I would like to know, how to get the center point from lines.

I have a deformed triangle grid (through kangaroo). Kangaroo only gives me a line output. There are triangles but they are only open curves. Grasshopper forget the grid information and so and I can't determine the center point.

I hoped that through a delaunay I could get the centerpoints but the mesh doesn't work so well.

Maybe you know how to get the centerpoints from trianges which are only curves?

A screenshot in attachmend.

Attachments:

Triangle.png, 46 KB

Permalink Reply by Damon on July 3, 2014 at 8:03am

It depends on how your lines and data is organized. If you share your definition, that would probably be easiest. Or at least a screen shot of a Panel and a Param Viewer plugged into the line output.

Permalink Reply by ng5 Alex on July 3, 2014 at 8:08am

To your first question you can try the followingstarting form a delauney mesh you get the center point of each face and then create a new mesh containing these points. you will need weavebird

http://www.grasshopper3d.com/group/weaverbird

for your second question if you input a mesh to the kangaroo component (input geometry) you get a mesh as output.it would be easier to help you if you posted your definition to take a look at

Permalink Reply by Philipp S on July 3, 2014 at 8:14am

I can do it later.

But it's for example like this:

You draw a lot of triangles in rhino and then you explode them. After that you open grasshopper and put all the lines into a curve parameter.

After doing that, is there any solution to get the center points from each triangle?

Thank you Damon and ng5 for your help and advice.

Permalink Reply by ng5 Alex on July 3, 2014 at 9:01am

well this is like banging your head on the wall. is there a very serious reason for exploding the triangles before you reference them into grasshopper? if yes reference the triangles before you explode them into grasshopper, find their center and then explode them.

your description is very general, if you become more specific about what you are, after then you can see help coming your way.

Permalink Reply by nikos tzar on July 3, 2014 at 9:32am

i believe you would have to rebuild a mesh from the lines you've got (weaverbird's mesh from lines component - or some other suggestion maybe?) and continue from there.

Attachments:

meshfromlines.gh, 9 KB

Permalink Reply by Philipp S on July 3, 2014 at 11:40am

Ok.

Finally back home. Sorry for my late reply.

In attachment is the grasshopper definition and a screenshot as well.

Attachments:

Img.png, 184 KB
Attractor_triangle.gh, 17 KB

Permalink Reply by Damon on July 3, 2014 at 11:58am

Confirmed nikos tzar's suggestion: Weaverbird's Mesh From Lines (Weave Back) creates a great mesh from your lines output.

Permalink Reply by Damon on July 3, 2014 at 12:16pm

I had a moment to play. Here's a quick definition that takes your output from the Kangaroo component and creates triangular surfaces inside each triangle using the centerpoint.

Attachments:

DivideTrianglesAtCenter.gh, 11 KB

Permalink Reply by ng5 Alex on July 3, 2014 at 3:01pm

you have to internalize the points (the ones that go to distance) or share the rhino file containing the points too.

edit nevermind i created some points myself

you can have a mesh from weaverbirds mesh from lines component, since your lines derive from the grid. if the were drawn in Rhino viewport randomly with one triangle beeing a closed polyline. the other not etc, there is no guarantee that the component would output a mesh with characteristics as described above.