GPU Lightmapper

A GPU accelerated standalone lightmap baker for Unity, powered by Vulkan

Features

• Supports Windows and Linux (Nvidia and AMD GPUs)
• Fast hardware accelerated ray-tracing (can utilize RTX)
• Easy to use (aims to be mostly a drop-in replacement)
• Realtime Preview
• Seam stitching with a least squares solver
• UV Packing with hole filling
• Open Image Denoise 2.0
• SH Lightmap mode (Monochromatic L1)
• Light Probe baking (L2 Spherical Harmonics)
• Multiple importance sampling for emissive meshes
• VRCLightVolumes baking
• Physically correct
• Lightmap Groups
• Directional Lightmaps
• Small binary size (only ~1MB)
• Emissive materials, Directional, Spot, Point, and Area Lights
• Fully standalone, with Unity URP and Built-In pipeline support

How to use

Notes

• Currently requires a GPU with the VK_KHR_ray_query extension, however it will support any GPU with a software BVH in the future. Check GPU support here https://vulkan.gpuinfo.org/listdevices.php, most modern GPUs should work.
• While the lightmapper is fully working, it is still in early stages, theres room for improvement and it might lack some features (Check the TODO list)
• If you'd like to see it further improved, consider supporting on Patreon

Denoiser Setup

Windows

1. Download the Windows .zip from https://github.com/RenderKit/oidn/releases
2. Extract it anywhere on your computer (e.g. C:\oidn)
3. Set the OpenImageDenoise_DIR environment variable to that extracted folder:
   • Press Start, type "environment variables", and open "Edit environment variables for your account"
   • Click New...
   • Name: OpenImageDenoise_DIR
   • Value: the path to the extracted folder (e.g. C:\oidn)
   • Click OK on all windows
4. Restart Unity and Unity Hub

Linux

• Fedora Linux: sudo dnf install oidn

Lightmapper Setup

VPM Package

• Install with the VRChat Creator Companion

UPM Package

• Download the release https://github.com/z3y/glim/releases
• Unzip the folder, open the package manager in unity Window > Package Manager
• Click + add package from disk and select the package.json from that folder

Baking

• Make sure to setup the denoiser first (otherwise denoising will be skipped)
• Setup the scene (mark GameObjects as static, generate lightmap uvs etc.)
• The lightmapper uses regular Unity light components, make sure to set them to baked
• Scale In Lightmap is also calculated differently from the Unity lightmapper, readjust it on the renderers if needed
• Menu Item Glim > Bake
• Adjust settings on the created GameObject and press Generate Lighting

Updating

• Close and reopen Unity to unload all currently loaded assemblies.
• Import the new package.

Lightmap Groups

• By default one lightmap texture is baked containing the entire scene
• To create multiple lightmaps add a Lightmap Group Selector component to a game object
• Right click, Create > Lightmap Group (Glim) asset and assign it to the selector component
• All the child GameObjects will be packed into that group

Discord

Stack

• Written in Rust, using the lightweight Ash Vulkan crate, with minimal dependencies
• Shaders written in Slang

Building

• Add the slang shader compiler at PATH
• cargo build --release
• Copy the compiled dll into the /Editor folder
• Alternatively you can run the test_preview or test_bake tests without Unity

Screenshots

World Link: https://vrchat.com/home/world/wrld_6d94340a-cf41-42f9-97f9-d94667e5cba0

Preview Window

Lightmap

Directional Lightmap