VRC Light Volumes | How to Use | Best Practices | Udon Sharp API | For Shader Developers | Compatible Shaders

How to Use

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VRC Light Volumes System • Light Volumes for Avatars • Light Volumes Quick World Setup • Point Light Volumes Quick World Setup
Regular Light Volumes
Point Light Volumes
Audio Link Integration
TV Screens Integration
How Light Volumes Work?

VRC Light Volumes System

VRC Light Volumes is fast and optimized nextgen lighting solution for VRChat. It can also work without VRChat, but was mostly designed to work with VRChat SDK3 and Udon.

VRC Light Volumes system consists of two main parts:

Regular Light Volumes is a fast and optimized solution that replaces Unity's light probes with a better per-pixel voxel based lighting. It's similar to Adaptive Probe Volumes (APV) in Unity 6, but with manual ReflectionProbe-like volumes placement and some other extra features.

Point Light Volumes is a fast and optimized custom lighting system that has it's own parametric Point Light, Spot Lights and Area Lights. Point Light Volumes are not voxel based, they forms the light parametrically, or based on special LUT textures (similar to IES). They can project light cookies or cubemaps. It can be up to 128 point lights visible in one scene at the same time. However, this system does not support realtime shadows.

Light Volumes for Avatars

You just need to use a shader that has VRC Light Volumes support and that's it. Nothing else to do!

Light Volumes Quick World Setup

1. Right-click in the Hierarchy and select Light Volume. You can also do it clicking on a Reflection Probe object, and new Light Volume will inherit its bounds.
2. Rename the new Light Volume to match the zone you're covering. Each volume must have a unique name.
3. In the Light Volume component, click Edit Bounds and resize the volume to fit your target area - similar to setting up a Reflection Probe. You can also just scale it with a scaling tool.
4. With Adaptive Resolution enabled, adjust Voxels Per Unit to control voxel density. Keep in mind: doubling the resolution of a 3D volume increases its file size by approximately 8x. Click Preview Voxels to show voxel placement grid to check the density.
5. Repeat this process to create as much volumes as you need to cover all of your areas.
6. Find the Light Volume Manager in your scene. It's automatically added when you create a Light Volume and lists all the volumes in your scene.
7. Assign a Weight to each volume. Volumes with higher weight have higher priority in overlapping areas.
8. Select your Baking Mode based on the lightmapper you're using. Bakery is highly recommended due to faster baking and better quality results.
9. Bake the scene lighting with your lightmapper (Unity Progressive or Bakery).
10. For reference, check out the Example scene in the Assets/Samples/VRC Light Volumes/[version]/Examples folder to see a working setup. You need to import the Samples through the Package Manager to see this folder. This process described here.

Point Light Volumes Quick World Setup

1. Right-click in the Hierarchy and select Point Light Volume. It will add a Point Light Volume object on your scene. It's just a simple configurable light source.

2. Select your desired Point Light Volume Type. It can be: Point Light, Spot Light, Area Light

3. In most of the cases you need to leave the Shape value as Parametric - it's the cheapest and the most useful mode. But if you want to project a light cookie (point light volume) or a cubemap (spot light volume), select Custom shape.

4. Point Light Volumes work differently compared to Unity’s built-in lights. They use light attenuation that more closely resembles how light behaves in the real world.

   First, set the Light Source Size. This represents the physical radius of the light-emitting surface, like a light bulb for point lights, or a flashlight reflector for spotlights. Once that’s set, adjust the Color and Intensity.

   Note that Intensity can be very high (in the hundreds or even thousands) for small Light Source Size values. This is because intensity here represents the light emitted per unit of surface area. A smaller light source must emit more intense light to achieve a reasonable visible range.

5. Debug Range shows the range in which point light volume affects meshes. Try not to overlap a lot of point light volumes. More overlaps means less performance. You can configure the Light Brightness Cutoff value in the Light Volume Setup to limit the effective range of the light and improve performance. Higher values reduce the light's visible radius, which generally increases performance, but results in less realistic light attenuation.

6. Enable Dynamic if your light can move in runtime. Otherwise it will be static, which is a tiny bit cheaper. If you want to make Dynamic lights auto-update their positions and other parameters in runtime, enable Auto Update Volumes in Light Volume Setup. Otherwise, they will stay in one place in game.