Unity Voxel Tracer

Work in progress voxel tracer. This is intended to be an offline solution for generating scene lighting and volumetrics.

Features

• Direct Lighting (Directional, Spot, Point, Area)
• Multi-Bounce Lighting
• Emissive Lighting
• Environment Lighting
• Volumetric Lighting

TODO / Notes / Ideas:

• Geometry thickening to solve problems with light leakage (conservative rasterization perhaps?)
• Improving scene albedo/emissive buffer capture by using the "Meta" pass rather than a replacement shader to support custom shaders.
• Optimizing Scene Voxelization even further.
• Would like to look into methods for potentially blurring and averaging results to improve quality. Something like a bilaterial blur that is "voxel aware" perhaps?

Screenshots

Voxel Trace: Final Lighting

Voxel Trace: Direct Lighting

Voxel Trace: Single Bounce Environment Lighting.

Voxel Trace: Scene Albedo Buffer

Voxel Trace: Scene Normals Buffer

Voxel Trace: Emissive Lighting

Voxel Trace: Scene Emissive Buffer

Voxel Trace: Volumetric Emissive Lighting.

Voxel Trace: Final Volumetric Lighting.

Voxel Trace: Volumetric Direct Lighting Only.

Voxel Trace: Volumetric Bounced Lighting Only.

Voxel Trace: Volumetric Environment Lighting Only.

Why?

This tool came about with the need to make the Baked Volumetrics effect no longer dependent on sampling from light probes in a scene. So building a voxel-based raytracer was necessary, and here we are. The raytracer is implemented all with Compute Shaders (NO RAYTRACING HARDWARE UTILIZED), so as long as the hardware supports compute shaders (most hardware now does) it should work on any GPU regardless of vendor which is the goal. It's worth noting that this tool serves as a foundation for potentially more things to come in the future (Real-time Voxel Based GI, Voxel Based Specular Reflections, Voxel Lightmaps, Scene To Voxel Mesh, etc.)

Sources / References / Credits

• pema99: Helped fix a big issue regarding TDR and GPU Readbacks for better baking stability, as well as additional advice and tips. (Thank you!)
• Morgan McGuire: Sample Scenes.
• Light Trees and The Many Lights Problem
• Unity SRP Core Sampling.hlsl
• Unity SRP Core Random.hlsl