HTrace: World Space Global Illumination HDRP

About HTrace: World Space Global Illumination HDRP – Unity Editor Tool & Plugin

Unity Global Illumination and World Space GI

HTrace: World Space Global Illumination is a fully dynamic software ray-tracing system for diffuse indirect lighting with infinite light bounces. It uses hybrid screen-space and world-space tracing, real-time scene voxelization, an irradiance cache, and advanced denoising to calculate indirect lighting without baking or asset pre-processing.

Dynamic Global Illumination

HTrace WSGI supports environments where objects, materials, and lighting change at runtime. Moving objects, including skinned meshes, participate in global illumination and can cast and receive indirect lighting and shadows. The rendering pipeline integration automatically injects required resources without manual resource setup or package customization.

World Space Lighting Features

• Hybrid Software Ray Tracing using screen-space and world-space data
• Real-Time Scene Voxelization with GPU-driven acceleration structures, time-sliced voxelization, adaptive culling, and mesh LOD control
• Irradiance Cache using a spatial hash structure for infinite light bounces
• ReSTIR GI with temporal and spatial denoising passes
• Emissive surfaces acting as indirect light sources with no stated upper limit on emissive lights
• Point and Spot light sources with emission and shadow calculations
• Dynamic sky lighting and occlusion
• Unity Adaptive Probe Volumes used as a ray-miss fallback and for accelerating multi-bounce calculations

Voxelization and Shader Support

Voxelization supports Lit, LayeredLit with its first 2 layers, TerrainLit with its first 4 layers, Unlit, and SpeedTree shaders out of the box. ShaderGraph and custom shaders are supported when they follow Unity's naming conventions, while the material evaluation code can be modified and extended.

Compatibility and Integrations

The asset supports DX11 and DX12 and has been tested with HDRP versions 14 and above and Unity versions from 2022.2 to 6000.5. The render-pipeline compatibility configuration specifies Unity 2022.3.62f3 as compatible with HDRP and not compatible with the Built-in Render Pipeline or URP.

• InTerra
• The Visual Engine
• DLSS 4
• FSR 3
• XeSS 2

Additional Technical Details

• GPU instancing through RenderX functions and native instancing for Terrain Trees and Terrain Details
• Custom instancing shaders are supported
• Single Pass VR support is experimental
• Orthographic cameras are untested and not guaranteed to work correctly
• MSAA is untested and not guaranteed to work correctly
• Unity LTS releases are recommended; bug fixes for non-LTS versions are not guaranteed

Use Cases

• HDRP environments requiring fully dynamic diffuse indirect lighting without baking
• Scenes with moving objects and skinned meshes that need to participate in indirect lighting
• Projects using emissive surfaces, Point and Spot lights, and dynamic sky lighting as lighting sources
• HDRP projects where world-space voxelization and multi-bounce indirect lighting are part of the rendering workflow

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