> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/AcChosen/VR-Stage-Lighting/llms.txt
> Use this file to discover all available pages before exploring further.

# Shader System Overview

> Overview of the VR Stage Lighting shader architecture and rendering system

## 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.

## Shader Architecture

The shader system is organized into several key categories:

### 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

### Static Light Shaders

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

### 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

## Rendering Pipeline

### Render Order

Shaders use specific queue orders for proper layering:

* **Projection Meshes**: `Transparent+1`
* **Volumetric Meshes**: `Transparent+2`
* **Lens Flares**: `Transparent+200`

### Stencil System

All lighting shaders use stencil reference 142 to prevent rendering where depth lights are placed:

```hlsl theme={null}
Stencil
{
    Ref 142
    Comp NotEqual
    Pass Keep
}
```

## Key Features

### GPU Instancing

All shaders support GPU instancing for efficient rendering of multiple fixtures:

```hlsl theme={null}
#pragma multi_compile_instancing
#pragma instancing_options assumeuniformscaling
```

### Render Pipeline Support

Shaders include dual SubShader blocks:

* First SubShader: Universal Render Pipeline (URP)
* Second SubShader: Built-in Render Pipeline

### 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

## Shared Functionality

### 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

### 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

## Performance Considerations

### 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

### Render Modes

Shaders support multiple transparency modes:

* **Transparent** - Standard alpha blending
* **AlphaToCoverage** - MSAA-based transparency
* **HQTransparent** - Enhanced transparency for volumetrics

## 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

### Mirror Support

Built-in mirror depth correction for VRChat mirrors:

```hlsl theme={null}
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);
}
```

## Next Steps

* [Moving Light Shaders](/api/shaders/moving-lights) - Detailed properties for moving lights
* [Static Light Shaders](/api/shaders/static-lights) - Static light shader reference
* [Volumetric Rendering](/api/shaders/volumetric) - Volumetric lighting techniques