---
title: "Light Bulbs"
canonical: "https://rmanwiki-27.pixar.com/space/RU/591691817/Light%20Bulbs"
format: markdown
---
This scene uses three different types of light.  

We have a globe light bulb, a fairground light bulb, and the neon signs themselves.

I’ll show you how I made both the lightbulbs in this lesson.  If you want to learn more about making Neons with Mesh Lights, there is a complete lesson [here](https://rmanwiki-27.pixar.com/space/RU/392953857/Neons)

### <span style="color: #4c9aff">Fairground Bulb</span>

![blueBulb.jpg](media://c24cabe3-7838-43bc-ab21-e40ff92d4535)

This bulb is pretty simple in its setup.  A glass shader has been applied to the bulb geometry, and the refraction color has been set to a blue color.  This refraction color will be randomised later to add color variation to each of the instanced bulbs.

Inside the geometry, there is a tiny sphere light with a radius set to 0.002 and both intensity and exposure set to 10.

Again, the intensity and exposure light values will be randomised to create the flashing and chasing of the light bulbs, but for now, it’s a good setting to start with.

![blueBulb_light.jpg](media://4f846c65-2dfe-4076-8e51-694de802f1a4)

![blueBulb_glass.jpg](media://7a1c75ad-3134-4aeb-b2b1-72266fd087a4)

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### <span style="color: #4c9aff">Globe Bulb</span>

![globebulb.jpg](media://f247a0a5-4c29-4e3b-8bce-aab1d8fdc411)

The globe bulb is slightly more complicated than the fairground bulb.

Here is the overall shader that was assigned to the bulb glass geometry.

![globe_setup.jpg](media://a0a4222c-4d68-4289-968c-86ba51656570)

Let’s break it down.

![globebulb_roughness.jpg](media://b81724b9-4cfc-4c6e-bb60-4a5d30c65de3)

In the top part of the shader graph, there is a simple triplanar grunge texture setup applied over the top of a *PxrFractal *node, which is then used as specular roughness.  This adds subtle imperfections to the reflections of the glass.

![globebulb_roughnessMap.jpg](media://e7147d39-c446-46e1-8ded-52cdffe49b5e)


The lower part of the bulb shader graph is where the real magic happens.

![globebulb_facing.jpg](media://32abd965-a6d7-4247-9469-74e4a02b07f1)

There are two *PxrPrimVar *nodes.  One called Bulb_COL and the other called Bulb_INT



If we take the RGB output from the Bulb_COL primvar and blend that over a slightly desaturated version of the Bulb_COL color, we can drive the blending with a *pxrfacingratio *node.  This allows us to creatively control the emissive look of the bulb as seen below.

![FacingRatio_2all.gif](media://e4cf6845-4e9a-4bb6-b903-cb8e90fbd0e4)

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