About Fluid Frenzy

Key Features Contents Requirements Limitations Pipeline Support Platform Support Feature Support

Installation

Package Manager Unity Package File

Samples

Importing Samples Universal Render Pipeline Running Samples River Grand Canyon Water Modifiers Volcano Terraform Fossil Finder Pool Simple Terraform Tiled Simulation World Runtime Setup State Sync GPULOD Terrain Scene Configuration

Setup

Simulation Time Step Water Simulation Terraform Simulation Layer Capture Simulation Baked Surface Playback Simulation Regions Fluid Channels Shader Stripper GPULOD Displacement Waves Flow Mapping Ocean FFT Cascades Sampling Universal Render Pipeline High-Definition Render Pipeline

Fluid Frenzy Toolbar

Accessing the Toolbar Simulation Preview Modes Sculpt Mode Modifier Mode Shared Settings Terrain or Fluid Layer Splat Channels Blend Mode Tool Properties

Fluid Simulation Components

Fluid Simulation Terrain and Obstacle Input Boundary Conditions Side Border Settings Domain Solver Initial Conditions Terrain & Ground Simulation Culling Extension Layers Create Collider Fluid Simulation Settings Creation Properties Second Layer Flux Fluid Simulation The Pipe (Flux) Model Simulation Characteristics Flux Fluid Simulation Settings Creation Specialized Flux Properties Flow Fluid Simulation The 2D Height Field Model Performance and Stability Solver Ocean FFT Coupling Flow Fluid Simulation Settings Creation Specialized Flow Properties Fluid Simulation Static Fluid Surface Bake Foam Layer Foam Layer Settings Foam Render Settings Foam Decay Settings Foam Pressure Settings Foam Wave Settings Shallow Foam Settings Turbulence Foam Settings Wetness Layer Wetness Layer Settings Rendering Settings Decay Settings Fluid Flow Mapping Fluid Flow Mapping Settings Erosion Layer Multi-Layer Terrain System Terrain Modification Processes Erosion Settings Terraform Layer Liquefaction (Solid Terrain to Fluid) Fluid Contact Reactions (Fluid and Terrain) Fluid Mixing (Fluid + Fluid to Solid Terrain) Fluid Contact Reaction Terraform Settings Terrain Modifier Terrain Modifier Settings Sediment Modifier Sediment Modifier Settings Terraform Modifier Fluid Particle Generator Splash Particles Surface Particles Fluid Particle System Fluid RigidBody Prerequisite Fluid Density Calibration Interaction Calculation Fluid Displacement Profile Fluid Interaction Profile Fluid RigidBody Lite Fluid Floater Fluid Simulation Obstacle Settings Fluid Event Trigger Fluid Ripple Zone (Beta) Fluid Ripple Impulse (Beta)

Fluid Rendering Components

Fluid Renderer Fluid World Renderer Fluid Renderer vs Fluid World Renderer Setting up a tiled world Which simulations are included General Mesh Rendering Water World Renderer Ocean FFT Settings Surface Renderer Render Properties Detail Wave Effect Detail Wave Settings HDRP Water Surface Properties Water Rendering Water Surface Underwater Effect Underwater Settings Current Particles Current Particle Settings Wet Lens Effect Wet Lens Settings Caustics Effect Caustics Settings Surface Reflections Fluid Decal Renderer Lava Lava Surface Under Lava Effect Shadows HDRP Water System

Fluid Shaders

Water Shader Stylized Water Shader Toon Water Shader Lava Shader Particle Shaders Fluid Decal Shader

Terrain

Simple Terrain Eight-layer terrain Terrain sculpting and painting Brush stamps Sculpt tools Height layers and splat Scene View shortcuts Strength, undo, and preview Terraform Terrain Terraform Terrain Shader Terraform Terrain (Single Layer) Shader

Fluid Modifiers

Fluid Modifier Volume Fluid Source Settings Fluid Flow Settings Fluid Force Settings Fluid Modifier Path Fluid Modifier Waves Fluid Modifier Pressure Foam Modifier

C# Interaction & Scripting

Fluid Simulation Manager Simulation control Multiplayer hooks (Beta) Adding fluid Adding sediment Applying flow and forces Sampling the simulation Per-simulation brushes Creating simulations, modifiers, and obstacles Simulations Surfaces In-memory settings Extension layers Terraform terrain and simulation Editor presets Fluid modifiers Terrain and terraform brushes Obstacles

Using ShaderGraph

Fluid Simulation Nodes Terraform Terrain Nodes Particle Nodes Current Displacement Shaders

Tiled Simulations

Purpose Setup Padding for Continuity

Physics Colliders

Which collider to use Surface Collider GPU-CPU Synchronization and Performance Collider Properties

Simulation Debugger

Edit Mode Preview

AI Skills

How to use them

Third-party Support

Enviro 3 Sky and Weather COZY: Stylized Weather 3 Curved World

Future Updates & Roadmap

Fluid Frenzy: 2026 Development Roadmap Roadmap Overview Upcoming Feature Breakdown Old Roadmap

Physics Colliders

Fluid Frenzy uses more than one kind of collider. Each one solves a different problem. A Unity Collider on a mesh is not enough on its own. Use this page to pick the right system. The Surface Collider settings for walking and raycasting on the water are documented below.

Which collider to use

  • Ground the water sits on The fluid needs a floor. That comes from Terrain Type on the Fluid Simulation. Use Unity Terrain or Simple Terrain for landscapes. Use Layers for indoor pools and mesh environments. See Layer Capture Simulation. Use Mesh Collider when a single static mesh is enough. The Pool sample uses Layers.

  • Fluid flowing around objects A Unity Collider on a rock will not make the water go around it. Add a Fluid Simulation Obstacle so the shape is written into the simulation heightfield. Place one from Fluid Frenzy > Obstacles, or add the component to an existing mesh. The fluid can flow around or over the obstacle. It cannot flow under it.

  • Walking or raycasting on the water Enable Create Collider on the Fluid Simulation. This builds a Unity TerrainCollider from the fluid surface so characters, rigidbodies, and raycasts can hit the water. This is the Surface Collider described in the rest of this chapter. It is optional and has a GPU readback cost.

  • Objects floating in the water Add a Unity Collider and a Rigidbody, then a Fluid Rigidbody or Fluid Rigidbody Lite. The Collider is used by Unity physics and by the buoyancy sampler. It does not replace a Fluid Simulation Obstacle. The Pool sample shows buoyancy with Layers capture. The Water Modifiers sample shows floating objects in a terrain simulation.

Fluid Floater pins debris to the surface and does not need a Collider.

Surface Collider

Manages the generation and synchronization of a Unity physics collider to allow physical interactions, such as collisions and raycasting, with the dynamic fluid surface and underlying terrain.

This optional feature enables physical interaction between standard Unity physics components and the elements simulated by Fluid Frenzy, specifically the FluidSimulation and the underlying SimpleTerrain/TerraformTerrain.

physics collider

GPU-CPU Synchronization and Performance

Since the fluid is simulated entirely on the GPU, the height data required for a physics collider must be transferred back to the CPU to generate the surface. This GPU-readback and the subsequent collider generation are inherently expensive operations.

To prevent the application from experiencing large stalls, the update process is managed by the SurfaceCollider class. It operates asynchronously and uses timeslicing to spread the computational load across multiple frames. The system provides a critical trade-off:

  • Increasing the number of timesliced frames reduces the per-frame cost.
  • However, this also increases the update delay, meaning the physics surface lags further behind the current fluid state.

The system includes several settings to modify both the quality of the generated collider and the performance characteristics of this synchronization process.

Collider Properties

Encapsulates settings used for configuring and initializing Surface Collider.

Fluid Simulation Create Collider

Property Description
Create Collider Toggles the generation of a Terrain Collider to handle physical interactions with the fluid surface.
Resolution Specifies the grid resolution of the generated Terrain Collider.

This value determines the density of the physics mesh. Higher resolutions result in more accurate physical interactions but increase generation time and physics processing overhead.

Internally, the actual grid size is set to resolution + 1 to satisfy heightmap requirements.
Realtime Controls whether the collider’s heightmap is updated at runtime to match the visual fluid simulation.

When enabled, the simulation data is continuously synchronized with the physics collider. Note that this process requires reading GPU terrain data back to the CPU and applying it to the Terrain Data, which can be resource-intensive and cause garbage collection spikes.
Update Frequency The interval, in frames, between consecutive collider updates when Realtime is enabled.

Increasing this value reduces the performance cost of the readback but causes the physics representation to lag behind the visual rendering.
Timeslicing The number of frames over which a single full collider update is distributed.

This feature splits the heightmap update into smaller segments, processing only a fraction of the data per frame. This helps to smooth out performance spikes and maintain a stable framerate, though it increases the time required for the collider to fully reflect a change in the fluid surface.