Add Attribute At Curve Control Vertex

[mmeijer]

Ideally I'd like to add an attribute for each control vertex CV
of my nurbs curve.

I didnt find a nice way to connect a locator, so I'm adding clusters
to the CVs. The problem with this is there are lots of nodes and
connections created. I would prefer something lighter if possible.

thanks for any ideas!

Mark

[failure]

Is this one quoestion or two unrelated questions? Why do you need attributes for? What's the final goal here?

[mmeijer]

Thanks for having a look, I'll try to elaborate..

Goal is to have a user-controllable attribute at each control vertex.

It's one question. The attribute I would get from the locator, for example..
I can get away with using scale for now. Later, I'll create my own node for
better visualization.

It doesn't have to be a locator, just some node that has an attribute
that the user can manipulate.

If I could connect a locator the same as clusters are connected, I'd be
happy.. a good starting point. But what is the bare minimum node and
connection count I need to just have a locator there?

[failure]

The final goal?

Having attribute at each vertex is possible (not necessarily the best) way to achieve the goal.

[joojaa]

Yes i agree its not necceserily the bbaest way to go... what is ist supposed to do?!?! I mean any array attrib could do it, as could any multi attrib too.

[mmeijer]

I'm using the curve as a base to define a tube, with the radius of the
cross-section defined at control vertices.

So the user could grab the locator/other, scale it
and see the resulting changes in the tubes.

[failure]

What's wrong with scaling the section isoparms of the extruded surface? Gives you exactly the same functionality without any effort on your behalf. In other words - maya already has what you're trying to do. You are reinventing the wheel here.

[mmeijer]

The surface is built solely on data from the curve and the radius
at the control points.

[failure]

How so when you don't know how to attach the radius data to CVs?
From user's point of view there's no real difference if he scale the locator you provide or the built in hull.

[mmeijer]

The user won't be scaling the hull, only the locator.

I was able to use clusters on the CVs for the radius.
I was hoping for a lighter solution, clusters include
a lot of nodes and connections.

Light is good for modelling.

[failure]

Yes light is good hence there's no need for locator nor any other setup. Let the user scale the hull. You are trying to introduce functionality that's already there. Just tell user to scale the hull if he need to change the raduis of the section.

[mmeijer]

By hull you mean the complete curve?

I'm aiming to modify the radius of a pipe (surface) built
around the curve, the length of the curve.
This pipe has variable width (cross-section)
based on the radius I want at each control vertex.

I would be happy with placing locators along the curve
but then the user would have to position them too,
which would be cool too.

[failure]

No I mean hull selection mode for the surface.

-create curve
-create circular profile curve
-extrude circular profile along curve
-right click on newly created surface, select "hull" from the menu.
now you are in the hull selection mode, you can select cv's of the whole isoparm with just one click and scale it. This will efectively scale the section radius if profile curve was a circle. Note that section hulls exist exactly at path curve cv positions so it's exactly like scaling the profile at the curve cv.

[mmeijer]

cool, but not what I'm trying to do

I'm building a plugin that will create my surface based on
the curve and radius at control vertices

I'm not extruding the surface, I just need attributes that
the user can manipulate.

[failure]

Oh, but that's exactly what you're trying to do.

Why do you ask on mel board if you're writting a plugin. There's the api section for that?

How do you actually plan to create the surface once the radii are set? Loft? Sweep? Extrude?

But if you insist; to store the data with curveShape node use array attribute:

CODE
addAttr -ln radius -dt doubleArray curveShape1;
setAttr curveShape1.radius -type doubleArray 4 0 1 3 2;

and to retrieve it:
CODE
getAttr curveShape1.radius;

Or with multi attribute which could be a tiny bit more convenient for gui user
CODE
addAttr -ln radius -m curveShape1;
setAttr curveShape1.radius[ 0:3 ] 0 1 3 2;

getAttr curveShape1.radius[ 0:3 ];

[mmeijer]

thanks a lot for your time man!

my plug will create a mesh from the API, the surface at a distance
radius from the curve.

I thought I'd ask here on MEL because I just want to connect an existing
node to points on a curve.

If I create an attribute array using addAttr, the user doesn't have
something to associate values with control vertices.
Not very interactive.

[failure]

It's as interactive as you code it to be.

Take a look at how paint effects are doing exactly the same thing. It even let you have arbitrary number of section radii at any parameter values independently of CVs or EPs. So it doesn't force you to manage large number of redundant radius values in situation where you just want simple linear gradient over the entire length of complex path.