Is there someway to add "thickness" to a renderable curve?

[tmcthree]

I'm making neon tubes.
Was hoping to use renderable curves, but when I apply a refractive material they tubes are rendered as a solid tube.
I'm wondering if there's some way to render the curve so that it is a hollow tube instead.

Failing that, is there any way to render a single polygon as if it had thickness, preferable without having to extrude it. Something at the attribute level, (like rounded edges).

Thanks in advance

[stezza]

Just render out a material ID and apply glow in the comp, much more flexible doing it that way.

[tmcthree]

Hi Stezza, thanks for your reply.
I'm not really concerned about the glow effect. I'm trying to find the easiest way to get the refraction of a hollow glass tube.
Renderable curves aren't working well because they create solid tubes which are optically dense within the entire volume. (There is a similar problem with paint effect curves)
A hollow glass tube is only optically dense on its surface, so you only see significant refraction towards the edges of the tube (where light is passing through more of the glass). So the obvious way to create an accurate tube is to extrude a tube with some surface thickness in the first place!
I've written a script which builds the tubes automatically, but it's creating a lot of geometry, so the scene gets a bit unwieldy.
So I was hoping that there was some checkbox at the shader or attribute level that could give a flat polygon some thickness when it comes to rendering. Something along the lines of "round edges". That way I could build the whole scene just using curves and things would be a lot more manageable.

[hermit.crab]

There isn't such an attribute. You can simply create a circular profile and extrude it along the path without the need for a renderable curve.

[yolov]

Maybe two curves at the same coordinates, but with different 'renderable curves' settings will help here. The "inner" one with lower thickness than the "outer" one.