Volumetric Rendering

Volumetric light cone rendering techniques and properties

Overview

Volumetric shaders create visible light beams and cones by rendering transparent meshes with sophisticated noise and gradient effects. These shaders are the most computationally intensive part of the VR Stage Lighting system and include multiple quality modes for performance optimization.

Shader Paths

DMX Control

• VRSL/Standard Mover/Volumetric
• VRSL/Wash Mover/Volumetric

AudioLink Control

• VRSL/AudioLink/Standard Mover/Volumetric
• VRSL/AudioLink/Wash Mover/Volumetric

Core Volumetric Properties

Quality Modes

_HQMode · bool · default: "false"

Enable high quality volumetric mode (experimental). Uses _NoiseTexHigh instead of _NoiseTex for better visual quality.

_PotatoMode · bool · default: "false"

Performance mode that disables noise sampling and extra texture reads. Significant performance boost at the cost of visual quality.

_UseDepthLight · bool · default: "true"

Requires depth light to function. When disabled, volumetric will render without depth fade.

Textures

_LightMainTex · texture · default: "white"

Main light texture for the volumetric cone. Typically a radial gradient.

_NoiseTex · texture · default: "white"

Standard quality noise texture for volumetric distortion.

_NoiseTexHigh · texture · default: "white"

High quality noise texture used when _HQMode is enabled.

Noise Configuration

_MAGIC_NOISE_ON_HIGH · bool · default: "true"

Enable high quality magic noise effect.

_MAGIC_NOISE_ON_MED · bool · default: "true"

Enable medium quality magic noise effect.

_2D_NOISE_ON · bool · default: "true"

Enable 2D noise texture sampling.

_NoisePower · float · default: "1"

Base noise strength/intensity.

_NoiseSeed · float · default: "0"

Random seed value for noise variation.

Magic Noise Settings

Magic noise creates dynamic, animated 3D noise patterns. Three quality presets are available:

High Quality Mode

_Noise2Stretch · float · default: "1"

Outside magic noise scale (high quality).

_Noise2StretchInside · float · default: "1"

Inside magic noise scale (high quality).

_Noise2X · float · default: "1"

Magic noise X axis scroll speed (high quality).

_Noise2Y · float · default: "1"

Magic noise Y axis scroll speed (high quality).

_Noise2Z · float · default: "1"

Magic noise Z axis scroll speed (high quality).

_Noise2Power · float · default: "1"

Magic noise strength (high quality).

Default Mode

_Noise2StretchDefault · float · default: "1"

Outside magic noise scale (default quality).

_Noise2StretchInsideDefault · float · default: "1"

Inside magic noise scale (default quality).

_Noise2XDefault · float · default: "1"

Magic noise X scroll (default quality).

_Noise2YDefault · float · default: "1"

Magic noise Y scroll (default quality).

_Noise2ZDefault · float · default: "1"

Magic noise Z scroll (default quality).

_Noise2PowerDefault · float · default: "1"

Magic noise strength (default quality).

Potato Mode

_Noise2StretchPotato · float · default: "1"

Outside magic noise scale (potato quality - typically unused).

_Noise2StretchInsidePotato · float · default: "1"

Inside magic noise scale (potato quality - typically unused).

_Noise2XPotato · float · default: "1"

Magic noise X scroll (potato quality).

_Noise2YPotato · float · default: "1"

Magic noise Y scroll (potato quality).

_Noise2ZPotato · float · default: "1"

Magic noise Z scroll (potato quality).

_Noise2PowerPotato · float · default: "1"

Magic noise strength (potato quality).

Intensity and Fade

_FixtureMaxIntensity · float · default: "1"

Maximum cone intensity. Higher values create brighter, more visible volumetric beams.

_FadeStrength · float · default: "1"

Edge fade strength. Controls how sharply the cone edges fade out.

_InnerFadeStrength · float · default: "0"

Inner fade strength. Creates a hollow cone effect when increased.

_InnerIntensityCurve · float · default: "1"

Curve for inner intensity falloff.

_DistFade · float · default: "0.1"

Distance-based fade. Cone fades at distance.

_FadeAmt · float · default: "0.1"

Depth blending amount. Controls soft particle intersection with geometry.

Blinding Effect

_BlindingStrength · float · default: "1"

Strength of the blinding/bloom effect when looking into the light.

_BlindingAngleMod · float · default: "1"

Angle modifier for blinding effect. Adjusts viewing angle sensitivity.

Gradient Controls

_GradientMod · float · default: "2.25"

Gradient modifier for solid beams (no GOBO).

_GradientModGOBO · float · default: "2.25"

Gradient modifier when GOBO is active.

GOBO Beam Splitting

Creates stripe effects in the volumetric cone for different GOBO patterns:

_GoboBeamSplitEnable · bool · default: "false"

Enable beam splitting for GOBOs 2-8.

_StripeSplit · float · default: "0"

Stripe split frequency for GOBO 2.

_StripeSplitStrength · float · default: "0"

Stripe split intensity for GOBO 2.

_StripeSplit2 · float · default: "0"

Stripe split frequency for GOBO 3.

_StripeSplitStrength2 · float · default: "0"

Stripe split intensity for GOBO 3.

_StripeSplit3 · float · default: "0"

Stripe split frequency for GOBO 4.

_StripeSplitStrength3 · float · default: "0"

Stripe split intensity for GOBO 4.

_StripeSplit4 · float · default: "0"

Stripe split frequency for GOBO 5.

_StripeSplitStrength4 · float · default: "0"

Stripe split intensity for GOBO 5.

_StripeSplit5 · float · default: "0"

Stripe split frequency for GOBO 6.

_StripeSplitStrength5 · float · default: "0"

Stripe split intensity for GOBO 6.

_StripeSplit6 · float · default: "0"

Stripe split frequency for GOBO 7.

_StripeSplitStrength6 · float · default: "0"

Stripe split intensity for GOBO 7.

_StripeSplit7 · float · default: "0"

Stripe split frequency for GOBO 8.

_StripeSplitStrength7 · float · default: "0"

Stripe split intensity for GOBO 8.

Animation

_PulseSpeed · float · default: "0"

Speed of intensity pulse animation.

Rendering Properties

_RenderMode · enum · default: "1"

Volumetric rendering mode:

• 0: HQTransparent - Best quality, most expensive
• 1: Transparent - Standard transparency
• 2: AlphaToCoverage - MSAA-based transparency

_BlendDst · enum · default: "1"

Destination blend mode. Typically set to One for additive blending.

_BlendOp · enum · default: "0"

Blend operation.

_ZWrite · bool · default: "false"

Depth buffer writing. Always false for volumetrics.

_AlphaToCoverage · bool · default: "false"

Enable alpha to coverage mode.

Performance Optimization

Quality Levels

High Quality - Best visuals, lowest performance:

_HQMode = true
_PotatoMode = false
_MAGIC_NOISE_ON_HIGH = true
_MAGIC_NOISE_ON_MED = true
_2D_NOISE_ON = true

Standard Quality - Balanced:

_HQMode = false
_PotatoMode = false
_MAGIC_NOISE_ON_HIGH = false
_MAGIC_NOISE_ON_MED = true
_2D_NOISE_ON = true

Performance Mode - Best performance:

_HQMode = false
_PotatoMode = true
_MAGIC_NOISE_ON_HIGH = false
_MAGIC_NOISE_ON_MED = false
_2D_NOISE_ON = false

Shader Variants

The volumetric shader compiles multiple variants:

• _MAGIC_NOISE_ON_HIGH - High quality noise
• _MAGIC_NOISE_ON_MED - Medium quality noise
• _USE_DEPTH_LIGHT - Depth-based effects
• _POTATO_MODE_ON - Performance mode
• _HQ_MODE - High quality mode
• _2D_NOISE_ON - 2D noise sampling
• _ALPHATEST_ON - Alpha testing

Total possible combinations: 128 variants

Optimization Tips

1. Reduce Cone Length: Shorter cones have less overdraw

   • Use _ConeLength and _MaxConeLength conservatively

2. Simplify Noise: Disable unused noise features

   • Turn off _MAGIC_NOISE_ON_HIGH if not needed
   • Use _PotatoMode on low-end hardware

3. Limit Fixture Count: Volumetrics are expensive

   • Consider using fewer fixtures with higher intensity
   • Disable volumetrics for background/ambient lights

4. Adjust Fade Settings: Reduce visibility distance

   • Lower _DistFade for shorter render distance
   • Increase _FadeStrength for sharper edges (less translucency layers)

5. Use Lower Resolution: If using render textures

   • Render volumetrics to lower resolution RT
   • Upscale for final composite

Technical Details

Vertex Shader Calculations

The vertex shader pre-calculates:

• Blinding effect based on view angle
• Camera angle and fade
• Stripe/split information
• Cone width
• World direction for depth correction
• Intensity, strobe, GOBO selection, and spin speed
• RGB color values

Fragment Shader Operations

The fragment shader performs:

• Multi-layer noise sampling (2D + 3D magic noise)
• Depth texture reading for soft particles
• UV-based gradient calculations
• GOBO stripe splitting
• Edge fade calculations
• Color blending and saturation
• Mirror depth correction

Performance Characteristics

Vertex Shader: Lightweight

• Simple position transforms
• Minimal branching
• Instanced property access

Fragment Shader: Heavy

• Up to 3 texture samples per pixel (in HQ mode):
  • _LightMainTex
  • _NoiseTex or _NoiseTexHigh
  • _CameraDepthTexture
• Complex noise calculations
• Distance-based fade calculations
• High overdraw on large cones

Depth Fade Implementation

Soft particle intersection uses depth comparison:

float sceneZ = LinearEyeDepth(SAMPLE_DEPTH_TEXTURE_PROJ(
    _CameraDepthTexture, UNITY_PROJ_COORD(i.screenPos)));
float partZ = i.screenPos.z;
float fade = saturate((sceneZ - partZ) / _FadeAmt);

This creates smooth transitions where volumetric cones intersect geometry.

AudioLink Specific

_RenderTextureMultiplier · float · default: "1"

Multiplier for render texture intensity when using AudioLink.

_UseTraditionalSampling · bool · default: "false"

Use traditional texture sampling instead of AudioLink-specific sampling.

_IntersectionMod · float · default: "1"

Intersection modification for AudioLink mode.

See Also

• Moving Light Shaders - Parent shader properties
• Shader Overview - System architecture
• Static Lights - Static light alternatives