Unity PRTGI

Precomputed Radiance Transfer Global Illumination for Unity URP.

Version

URP 2022.3.17f1

URP 14.0.9

Create Probe Volume: Add a ProbeVolume component to a GameObject in your scene
Configure Grid Settings:
- Probe Size: Set X, Y, Z dimensions for the 3D probe grid (e.g., 8x4x8)
- Probe Grid Size: Distance between probes (e.g., 2.0 units)
- Bake Resolution: Choose 256x256 or 512x512 for cubemap quality
Bake Data: Click "Bake Data" button in the inspector to:
- Generate probes in 3D grid formation
- Capture G-buffer data (world position, normals, albedo) from each probe location
- Store precomputed radiance transfer data for real-time global illumination
Data Storage: Baked data is saved in ProbeVolumeData asset for runtime use

Note: Baking may take time depending on probe count and resolution. Progress is shown in the editor.

The system provides two-level debugging modes to help understand and debug PRT global illumination effects:

None: No debug visualization
ProbeGrid: Shows probe grid layout for visualizing probe distribution in 3D space
ProbeRadiance: Shows probe irradiance spheres, visualizing light information captured by each probe

When ProbeRadiance mode is selected, click on probes in the scene for detailed debugging:

IrradianceSphere: Shows irradiance sphere (default), sphere color reflects SH lighting coefficients
SphereDistribution: Shows spherical sampling point distribution (yellow for surfaces, blue for sky)
SampleDirection: Shows sampling ray directions from probe position to sample points
Surfel: Shows surfels (surface elements) with green normals indicating surface orientation
SurfelRadiance: Shows surfel radiance, color represents light intensity received by each surfel

Note: Debug modes are only available in editor, debug visualization is automatically hidden at runtime.

Enable Multi Frame Relight in ProbeVolume to relight part of probes each frame to reduce per-frame cost.