directly access control points of a curve

Replies to This Discussion

Permalink Reply by Daniel González Abalde on September 14, 2015 at 4:22am

This perhaps can help, but I think that is not what you want. The script of the second link is not shared, but I can send you by mail if you need it (it is very similar to the first).

http://www.grasshopper3d.com/profiles/blogs/deform-a-mesh-manually-...

http://www.grasshopper3d.com/video/transform-manually

Permalink Reply by _fb on September 14, 2015 at 5:34am

Thanks,

Congratulations on this, seems very useful.

And it seems much more advanced than what I had in mind. Still haven't been able to figure out how you'd access the components. From what I understand, Rhino can't do this (unlike Maya, for example, where it's easy) but I hope I am wrong. 

All I need, right now, is a way to have GH (or a python script) do as attached image (approximately) shows. 

Again, thank you.

F

Attachments:

• simple concept sketch.png, 30 KB

Permalink Reply by Daniel González Abalde on September 14, 2015 at 6:19am

What do you mean by component? the property of control points of a curve? If you mean that, from Rhino you can access the control points by pressing F10 (and F11 to hide them), and from Gh you can do something like this, for example.It is what you need?

Permalink Reply by Daniel González Abalde on September 14, 2015 at 6:20am

Lately it is failing too upload files -_-

Attachments:

• RaplaceControlPointOnCurve.gh, 14 KB

Permalink Reply by _fb on September 14, 2015 at 6:39am

Yes, with components, I mean the parts that make up a geometry, such as control points for curves, vertices or edges or faces for meshes, etc.

(sorry for the word "component", which I realise in GH has a different meaning...

-

If I could "feed" e.g. the control points of a drawn curve directly into GH, see attached (or "access" with e.g. python), I could solve the problem... 

Attachments:

• directly assign control points to GH.png, 33 KB

Permalink Reply by Daniel González Abalde on September 14, 2015 at 8:14am

 You can access to the control points in Gh using the Control Points (CP) component, and then manipulate that point list, replacing, removing, adding new points... and with that new list you create the new curve.

Grasshopper does not work directly on the model, working on the process to generate the model. But you can access all the properties and manipulate data.

In programming, a component is a specific function that is individualized or given proper form, to facilitate relations with other components in order to build an application using predefined elements and therefore easier to manage. Data flow through the components to be handled. When a component needs data to be executed, these data are input data or parameters and his result is output parameters. The parameters can be any type of data, usually the lower abstraction objects, such as numbers or geometry, but can also be other pieces of code. I do not know if it's correct to call the controlpoints as components, but in RhinoCommon library are hierarchically as properties in the  nurbscurve class and you can also access them using specific methods.. Maybe, but it is preferable to avoid ambiguity in this case call it as input parameters to the points for build a curve, or in case of extract them of a curve, the control points property.

Permalink Reply by _fb on September 18, 2015 at 7:34am

Many thanks again, Daniel.

Perhaps my wording was clumsy, but what I meant was: 

Instead of using points, lines, surfaces, meshes, etc. drawn in Rhino to feed GH definitions, is there a way to use the control points of such a line (or vertices of a mesh...)? In other words not the Rhino object itself but a "sub-component" of it, in this case the control points of a line. (In MEL, for example, you would address this ObjectName.CV[n].)

(In this case, one could –in Rhino– select specific points to trigger a GH process)