added emission shader somehow bleeds into the outcome of the diffuse one

Hello fellow Blender artists!

I have a very specific question regarding emission materials.
If I add them to another shader I get strange light bleedings I do not expect logically. But of course I can be totally wrong.


The image says it all but my questions are: is this a bug or a feature?
How and why would an added emission shader influence the outcome of the other shader inside 1 material?
I guess the emission acts as usual - a light source - here, but should it? It makes sense to me when there’s a separate emitting material on the model, that of course should influence everything else. But if I’m mixing them in 1 material I assume that I’m mixing (or in this case adding) the 2 shader’s final outcome together.

Thanks in advance if you can enlighten me on this!

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try using a greater than math node to replace the color ramp. use strength value

then try replacing add shader with mix shader. remove math from strength, plug into fac.

how does it compare?

you could also try older blenders.

It lights up the diffuse parts because it emits light. If you don’t want this, maybe you need to use compositor. I’m not sure you can switch off the lighting diffuse shader receives from emissive objects or parts.

ah, self lighting. hm, should have thought of that.

kesonmis is correct, using an emission shader for cycles shadeless material has a side effect, it emits light. You can use a is_camera_ray boolean to stop the emission after the first bounce, like this.


I see. Thank you guys! You’ve helped a lot!
I still think this shouldn’t happen inside 1 material but if this is what it is I’ll solve it with Photox’s workaround!

wouldnt it be better to plug the diffuse color in where the transparent is? that way the world sees the shaded stuff, and the emission acts more like an overlay.

multiply the factor by the isCamera and cut out an entire mix.

You are probably correct that the diffuse should go into that slot to avoid transparency in the middle fresnal mix values.