View Full Version : Light exclusion by surface?

02-02-2010, 09:52 AM
Is there an equivalent to using the Light exclusion features of Objects, but for Surfaces?

I want to separately light the eyes in my mesh, but don't want to separate the eye geometry from the body geometry.


02-03-2010, 03:19 PM
Not really. There's a light node here
that you could use to set up something like that but it would be complicated and maybe very limited. You'd have to use this node on all the surfaces, not just the eyes.

Lighting them separately would'nt allow shadows from the head to the eyes, are you sure you need to do it that way? Surface changes may get you what you need, and probably look more realistic.

Chris S. (Fez)
02-03-2010, 03:43 PM
Modo allows per-surface exclusion and is quite handy IMO. If you are rendering with native Lightwave I believe you can use the BDRF shader (will not work in Fprime).

02-03-2010, 03:45 PM
If you are rendering with native Lightwave I believe you can use the BDRF shader (will not work in Fprime).
Unfortunately, the brdf shader can give you black artifacts if you raytrace reflections with it...

02-04-2010, 07:52 PM
Worleys G2 plugin allows for light exclusion on a per-surface basis.


02-05-2010, 12:54 AM
It's a pity I don't have an extra 200 bucks laying about.

Captain Obvious
02-05-2010, 02:19 AM
If you download Michael Wolf's excellent (and free) dbwTools (http://www.db-w.com/component/option,com_remository/Itemid,84/func,select/id,13/), you can use the single light lambert node shader to render just a particular light on a surface. Or you can SUBTRACT it from a normal Lambert diffuse shader, to remove a particular light from a surface.

To subtract, just add a Shader > Diffuse > Lambert, and then a Math > Vector > Subtract, and the Single Light Lambert. Then plug the first lambert into the 'A' input of the subtract, and the Single Light Lambert into the 'B.' Then plug the same color texturing into both the diffuse shaders, and the Subtract node into the Diffuse Shading input. Easy peasy! :)

I don't know of a good way of doing this for specular highlights, though...

02-05-2010, 03:15 AM
As I pointed out on SQ, shaderMeister also includes a light groups node (well, two them) that can limit the lights visible to upstream nodes.

It's certainly overkill just for a single problem like this.