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Introduction

VR Stage Lighting uses a sophisticated shader system built on Unity’s shader pipeline, supporting both the Built-in Render Pipeline and Universal Render Pipeline (URP). The shader system provides realistic stage lighting effects including volumetric rendering, projection mapping, and DMX/AudioLink control.

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Shader Architecture

The shader system is organized into several key categories:

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Moving Light Shaders

  • Standard Mover - Versatile moving head spotlight with projection capabilities
  • Wash Mover - Wide-beam wash light for area illumination
  • Basic Laser - Laser beam effects
Each moving light type includes three mesh components:
  • Fixture Mesh - Physical appearance of the light fixture
  • Projection Mesh - Light projection and GOBO patterns
  • Volumetric Mesh - Volumetric light cone rendering

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Static Light Shaders

  • Static Light Projection - Fixed position projection lights
  • Static Light Lens Flare - Realistic lens flare effects for static lights

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Control Variants

All main shaders come in two control variants:
  1. DMX Control (VRSL/...) - Controlled via DMX512 protocol through render textures
  2. AudioLink Control (VRSL/AudioLink/...) - Driven by audio reactive AudioLink system

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Rendering Pipeline

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Render Order

Shaders use specific queue orders for proper layering:
  • Projection Meshes: Transparent+1
  • Volumetric Meshes: Transparent+2
  • Lens Flares: Transparent+200

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Stencil System

All lighting shaders use stencil reference 142 to prevent rendering where depth lights are placed: 
Stencil
{
    Ref 142
    Comp NotEqual
    Pass Keep
}

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Key Features

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GPU Instancing

All shaders support GPU instancing for efficient rendering of multiple fixtures: 
#pragma multi_compile_instancing
#pragma instancing_options assumeuniformscaling

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Render Pipeline Support

Shaders include dual SubShader blocks:
  • First SubShader: Universal Render Pipeline (URP)
  • Second SubShader: Built-in Render Pipeline

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Shader Variants

Common shader variants include:
  • _ALPHATEST_ON - Alpha to coverage rendering
  • _MAGIC_NOISE_ON_HIGH / _MAGIC_NOISE_ON_MED - Volumetric noise quality
  • _USE_DEPTH_LIGHT - Depth-based occlusion
  • _POTATO_MODE_ON - Performance mode
  • _HQ_MODE - High quality mode

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Shared Functionality

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Include Files

Shaders use shared include files for common functionality:
  • VRSL-Defines.cginc - Property definitions and uniforms
  • VRSL-DMXFunctions.cginc - DMX grid sampling and control functions
  • VRSL-AudioLink-Functions.cginc - AudioLink integration
  • VRSL-StandardLighting.cginc - Lighting calculations

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DMX Grid Sampling

The system uses render textures for DMX control:
  • _Udon_DMXGridRenderTexture - Raw DMX values
  • _Udon_DMXGridRenderTextureMovement - Smoothed movement data
  • _Udon_DMXGridStrobeOutput - Strobe timing
  • _Udon_DMXGridSpinTimer - GOBO rotation timing

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Performance Considerations

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Quality Modes

The shader system includes multiple quality levels:
  1. High Quality Mode (_HQMode)
    • Enhanced volumetric sampling
    • Higher resolution noise textures
    • Best visual quality
  2. Default Mode
    • Balanced performance and quality
    • Standard noise sampling
  3. Potato Mode (_PotatoMode)
    • Disabled noise sampling
    • Reduced texture reads
    • Maximum performance

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Render Modes

Shaders support multiple transparency modes:
  • Transparent - Standard alpha blending
  • AlphaToCoverage - MSAA-based transparency
  • HQTransparent - Enhanced transparency for volumetrics

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Depth System

The shader system uses Unity’s depth texture for:
  • Soft particle effects (depth fade)
  • Mirror depth correction
  • Occlusion testing (lens flares)
  • Intersection highlighting

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Mirror Support

Built-in mirror depth correction for VRChat mirrors: 
inline float4 CalculateFrustumCorrection()
{
    float x1 = -UNITY_MATRIX_P._31/(UNITY_MATRIX_P._11*UNITY_MATRIX_P._34);
    float x2 = -UNITY_MATRIX_P._32/(UNITY_MATRIX_P._22*UNITY_MATRIX_P._34);
    return float4(x1, x2, 0, 
        UNITY_MATRIX_P._33/UNITY_MATRIX_P._34 + 
        x1*UNITY_MATRIX_P._13 + x2*UNITY_MATRIX_P._23);
}

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Next Steps

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