I am trying to set up an emission shader which is bright in the dark areas of the scene and then dims in the lighter areas, but I’m not seeming to get it to work. Any suggestions?
Are you using cycles - then it’s not possible i’m afraid.
Cycles cannot set shader properties like colour or brightness based on the amount of incident light.
try mixing with a transparent or diffuse shader, depending on what your looking for. volumes could be useful.
By definition, an emission shader doesn’t catch any shadow. So yours works as expected.
You might want to mix a diffuse shader to have shadows on your emitter and tweak the factor at your will.
But, if you want to make cycles decide where to mix based upon other objects/environment shadows, then no, that’s not possible.
Can’t you use something like a lightpath node to determine “lighted areas” get defuse and “dark areas” get emission?
Also the lit and shadow areas aren’t as simple as you might think. A shadow means absence of light, and when you put an object in a scene like that, there’s a cast shadow from other objects and also from itself because all of the objects in front of a light source blocks the light. Then the light bounces from other surfaces and some of it finds its way back on the object, including the shadow areas. Even if Cycles had a closed loop from what it’s rendering back to materials, it would still be hard to distinguish which parts should get influenced by what.
It’s possible to do that after rendering in the compositor or using another program. Could render a mask which only consists of full white materials and lights, which should also showcase the problem. Could exclude the object from the mask. When you have a suitable mask, could then bring in separate diffuse and emission renders and use the mask to mix the two.
You can bake a only-direct diffuse pass and then use it as a mask for the mix. YouTube is full of bake tutorials
Thank you guys for the clarification!!