negative lighting

this is hypothetical. Let’s say I have a box with an open lid. I want to place a negative light inside the box the intensify it’s shadows… How would I do this and avoid the negative light from passing through the polygons to the otherside? Everything I try leads me to a box that’s lit negatively inside and outside as well.

EDIT: What I’m really trying to do is compensate the lighting of the inside of my character’s mouth, so that it appears realistically lit as opposed to a full ambiance caused by the sun lamp that’s beaming down

I’m sure there is a better way but I’d copy the box (shift d) the scale it down just a bit. So that the viewer couldn’t tell that I created a lining for the inside of the box but the render could handle it the way I wanted.

If I wanted to use a material to get the effect of lighting then I would just assign a new material ID to the mesh and texture as opposed to creating a completely new mesh inside the box.

But unfortunately using a material is not sufficient. I am wanting to use lighting to achieve my effect so that I can animate things like the energy of the lamp for when my character’s mouth opens etc.

This is a pretty common technique in blender based on many blender conference videos I watch. But I’ve never tried to implement it until now. So how the heck can I control this?

Can you use the negative light as a layer light - place the negative light and the box in the same layer, and click the layer option in the lamp panel.
Pic1 without negative light, Pic2 with negative layer light, box and light on the same layer.

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I don’t seem to get those same results… My “box” and negative light are on the same layer, but the negative light still passes through the polygons to the outer ones (because the outer polygons are still on the same layer, naturally)

I think I figured out my solution. I’m surprised that nobody responded to this one sooner with this. I had forgotten about this feature, and am surprised I didn’t think to use it in the first place.

  1. Assign a new material ID to the faces that you want affected by the negative light only
  2. Set that material the same as you would for the other faces, however Utilize the GR: input field in the shaders panel. You can assign the material to be affected to a specified lamp group of your choice there.