Driving parameters with attributes

[phong]

Hi!

I try to do paint values on a polygon mesh to use these values later on in some nodes. I tried using the point() function with having $PT as the point number variable but then there's an error popping up in the node saying that this expression causes an infinite recursion. So how do I use attributes to drive my parameters then when I'm not in the PointSOP?

Thank you very much!

Phong

[Darric]

Which SOP are you aiming the point expression at? Make sure it's not the same one that you're using it in, but one higher up the stream. Using an expression like opinputpath to get the node above might make the most sense.

[phong]

I used opinputpath(".",0) in the expression. The attribute gets transfered far up higher in the stream. I tried severel SOPs with the same result. But this approach should be theoretically possible or not?

Cheers,

Phong

[kgoossens]

Can you give an example scene?

[phong]

In this example I get an 'unable to evaluate expression' error,

example_scene

[graham]

The SoftTransform SOP does not support operations on a per-point basis. If you look in the help for the operator you will see that PT is not listed in the Local Variables list. The operator has no idea what it means and thus errors.

Edited February 20, 2010 by graham

[phong]

Ah now I understand. Is there any other way to use attributes to drive parameters like in SoftTransform or other SOPs without using the $PT variable then?

[sanostol]

the operator does not support this, it works not on a per point basis. use the pointsop for this . or use the peaksop and feed in custom normals to get the desired effect.