I am making an old fashioned incandescent light bulb in cycles, with the coil inside having an emissive material. However, I am trying to find a good way to make the glass material. If I use an actual glass material with low roughness, it is too dim. If I use a glass material with high roughness, I can't see the filament, which I want to see. The best way to pass the light through that I found was a completely transparent material, but then you obviously cant see the glass. Is there any way to make a material that passes light through like a transparent bsdf but still shows up?enter image description here


1 Answer 1


I would think you could use a principled shader with the transmission level set to 1. Here's a demo scene:

demo scene with two spheres on a plane

There's a cylinder inside the first sphere and it acts as the filament:

wireframe showing filament inside sphere

The plane and the back sphere have simple principled shaders. The only changed setting on either is the color.

The front sphere has a principled shader with roughness well down and transmission set to 1:

fake glass principled shader settings

simple fake glass shader node group

Note: if you look at this scene in Lookdev/Viewport shading you won't see the filament because EEVEE is used in lookdev:

no filament in lookdev mode

My world emits no light and there are no other lights in the scene but the filament:

dark world

and the filament is just an emitter:

filament shader node group

The blackbody simply sets the color to daylight.

Here's the render view with that setup:

render view

or you can set the color to reddish by changing the temperature to 1500:

reddish light

or lower the intensity of the bulb:

low intensity light

note that the yellow outline of the cylinder is because it's selected. Here's an actual render:

actual render

  • $\begingroup$ Using that with a slightly higher roughness works, but now I have weird square artifacts in my render. I'm adding a picture to the original post. Any ideas? I am running at 128 samples and double light bounces. $\endgroup$ May 9, 2021 at 17:30

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