Volunex – OpenVDB & Volumetric Effects Suite for HDRP

Volunex – Advanced Volumetric Effects for HDRP

Create cinematic volumetric clouds, smoke, explosions, tornadoes, atmospheric effects, animated OpenVDB sequences, and real-time GPU fluid simulations directly inside Unity.

Volunex is a volumetric rendering and effects toolkit designed for artists, environment designers, VFX creators, and developers working with HDRP.

It combines OpenVDB conversion, Texture3D volume rendering, procedural volume generation, animated volume sequences, interactive volumetric effects, particle-system integration, and a real-time GPU fluid simulation framework in one package.

OpenVDB Importing

Import OpenVDB density volumes into Unity using the built-in Volunex VDB conversion workflow.

Features include:

• Import .vdb density files

• Select a density grid by name

• Automatic scalar-grid fallback

• Numbered VDB sequence detection

• Animated sequence importing

• Adjustable sequence frame rate

• Automatic active-volume bounds detection

• Aspect-ratio-preserving conversion

• Conversion to Unity Texture3D assets

• R8 density storage for practical runtime rendering

Volunex converts sparse OpenVDB grids into dense Unity Texture3D assets optimized for use with its real-time raymarch renderer.

The optional editor conversion backend uses Python, OpenVDB and NumPy packages installed through the included backend installer.

Procedural Volume Editor

Generate volumetric effects without requiring external VDB files.

Available generators include:

• Clouds

• Smoke

• Tornadoes

• Explosions

• Heightmap-based volumes

• Imported Texture3D sources

Available procedural noise modes include:

• Perlin

• Worley

• Ridged

• Hybrid

Create individual volumes or animated Texture3D sequences directly in the Unity Editor.

Real-Time Volume Rendering

Volunex renders volumetric density using an HDRP-compatible raymarching shader.

Rendering controls include:

• Adjustable raymarch steps

• Empty-space skipping

• Density control

• Light absorption

• Edge fading

• Directional lighting

• Local light support

• Emissive volumes

• Density-shaped shadows

• Shadow softness and quality controls

• Wind animation

• Unity WindZone integration

The system is suitable for clouds, smoke, fire-like effects, magical volumes, dust, atmospheric effects, and other volumetric visuals.

Animated Volume Sequences

Create and play animated Texture3D sequences.

Features include:

• Adjustable playback speed

• Sequence frame rate

• Play and stop controls

• Randomized sequence starting time

• Frame interpolation

• Runtime sequence playback

Animated sequences can be used for smoke simulations, explosions, tornadoes, clouds, and other pre-generated volumetric effects.

Interactive Volumes

Volunex volumes can react to gameplay.

The included interaction system supports projectile and explosion-style density carving.

Examples include:

• Bullets passing through smoke

• Temporary holes in cloud volumes

• Explosions dispersing local density

• Interactive volumetric gameplay effects

• Automatically recovering density after interaction

Interaction strength, radius, softness, duration and recovery can be customized.

Particle System Integration

Use volumetric assets with Unity Particle Systems.

Volunex can render particles as individual volumetric instances using Texture3D density or animated volume sequences.

Create effects such as:

• Volumetric smoke particles

• Explosion clouds

• Dust bursts

• Fireballs

• Destruction smoke

• Magical effects

• Atmospheric particles

Controls include density, absorption, raymarch quality, emission, shadows, size, and opacity over lifetime.

Destruction Effects

The included destruction smoke component can emit volumetric smoke effects from collisions or scripted events.

This makes Volunex suitable for destruction systems, impacts, environmental effects, explosions, and gameplay VFX.

Real-Time GPU Fluid Simulation

Volunex also includes an experimental real-time 3D GPU fluid simulation framework.

The simulation includes:

• 3D velocity fields

• Density simulation

• Temperature simulation

• Semi-Lagrangian advection

• Buoyancy

• Vorticity confinement

• Divergence calculation

• Jacobi pressure solving

• Pressure projection

• Fluid emitters

• Directional, point and vortex forces

• Collider obstacle support

• GPU raymarch rendering

The fluid solver is designed for real-time smoke and fire-style volumetric effects.

Quality presets can be adjusted according to the target hardware and required visual quality.

Fluid Simulation Components

Volunex Fluid Volume

Controls the GPU simulation and rendering volume.

Volunex Fluid Emitter

Injects density, heat and velocity into the simulation.

Volunex Fluid Force

Adds directional, point or vortex forces to the fluid.

Volunex Fluid Collider

Adds collider-bound obstacle regions to the simulation.

Included Demo Content

Volunex includes ready-to-use examples and generated test assets:

• Main Volunex demonstration scene

• Fluid simulation demonstration scene

• Procedural cloud density asset

• Animated procedural smoke sequence

• Generated tornado sequence

• Perlin noise texture

• Cellular noise texture

• Ridged noise texture

• Turbulence noise texture

• Radial volume mask

• Plume mask

• Heightmap test textures

• Example materials and shaders

Editor Workflow

Volunex adds convenient tools under:

Tools > Volunex

Available tools include:

• Setup

• Create Volume in Scene

• Procedural Volume Editor

• Import OpenVDB

• Fluid Simulation tools

The package is designed to provide both artist-friendly editor workflows and runtime scripting access.

Performance Controls

Volume rendering quality can be adjusted through raymarch step counts, shadow samples, empty-space skipping and density settings.

The GPU fluid solver also supports adjustable simulation resolutions.

Recommended starting fluid resolutions:

Low: 32³

Medium: 64³

High: 96³

Ultra: 128³

Start with Medium quality and increase resolution according to target GPU performance.

Requirements

• 2021.2.x to 6000.3

• High Definition Render Pipeline (HDRP)

• Compute Shader capable GPU for real-time fluid simulation

• 3D texture and UAV support for GPU fluid features

The OpenVDB importer uses an optional editor-side conversion backend. The backend installer downloads the required Python, OpenVDB and NumPy packages into the project's Library environment.

No OpenVDB runtime dependency is required for already-converted Texture3D assets.

Ideal For

• Environment artists

• VFX artists

• Cinematic scenes

• FPS and action games

• Destruction effects

• Atmospheric environments

• Horror games

• Sci-fi effects

• Clouds and weather effects

• Smoke and explosion effects

• Prototype and research projects

Volunex provides a flexible foundation for bringing high-quality volumetric effects and OpenVDB-based workflows into HDRP.