How to control curve color using Node Editor

[gautham.chandran47]

Is there any way to control a curves color using node editor ? 

I know we can change the color using drawing overrides. But how to contol it ? 

My need is I want to make my controller change its color if its value is greater than zero. So it  makes a visual representation of the values I tweaked ( facial UI controls ) 

[Roland.Reyer]

Yes, it is possible to connect to attributes like the override color even though they are not visible by default.

The easiest way is to use MEL:

setAttr "myNURBSCurve.overrideEnabled" 1;
connectAttr myControlNode.outColor myNURBSCurve.overrideColorRGB

Then you get this:

You can also RMB on the node with the hidden attributes and "Show all Attributes":

... and then locate the attribute and connect:

[gautham.chandran47]

Thanks for the quick replay, 

It worked as you said, but unfortunately I couldn't change the color  

The "myControlNode" you mentioned is a layered texture ? Thats how I connected it.

If else would you please tell me which node is the "myControlNode" ?

[Roland.Reyer]

I wouldn't take a texture node because how do you then control the color change?

For a rig with a certain condition to change the color an expression might be the right way.

This example would change the color of the nurbsCircle1 at frame 26:

if (frame>25) {

     nurbsCircle1.overrideColorR = 1;

     nurbsCircle1.overrideColorG = 0;

     nurbsCircle1.overrideColorB = 0;

} else {

     nurbsCircle1.overrideColorR = 0;

     nurbsCircle1.overrideColorG = 0;

     nurbsCircle1.overrideColorB = 1;

}

You can't enter the expression editor from the Attribute Editor (like with most other attributes), you have to open it and create the expression from scratch.

[gautham.chandran47]

unfortunately if doesn't seems working. I now understand i should put a texture node to control curve color, but is there any other node we can use in this situation ? the script is giving me errors. 

[Roland.Reyer]

Yes, it won't work in the Script Editor.

This example works only in the Expression Editor:

Create a NURBS circle.

Set "Enable Overrides" ON and "Color" to "RGB"

and then in the Expression Editor:

[gautham.chandran47]

I did everything as you mentioned and the expressions didn't give any errors but I cant find the out put. The color is not changing..  

Any idea why ?

Could you please post the work file for a reference maybe ?

I dont know what I'm doing wrong. 

[gautham.chandran47]

When i combined the both methods you mentioned it came out alive ...   

[gautham.chandran47 · Accepted solution]

Thanks a lot . as you mentioned I created a "layerd textured node" and curve and renamed it accordingly;

setAttr "myNURBSCurve.overrideEnabled" 1;
connectAttr myControlNode.outColor myNURBSCurve.overrideColorRGB

You were right about using a texture node to control curve color,

so I changed the "color" mode from "index" to "RGB" in the drawing overrides on attribute editor.

And after that I could easily change the color of the curve through the layered texture's properties.

I can even animate it.