C# Interaction & Scripting

Fluid Frenzy exposes a static API on FluidFrenzy.FluidSimulationManager for querying and modifying all registered Fluid Simulation components in the scene. Each call iterates every active simulation and applies the operation where the world position falls inside that simulation’s bounds.

The manager is driven automatically by FluidSimulationLoop, which hooks into Unity’s player loop (FixedUpdate by default, or Update when FLUIDFRENZY_RUN_UPDATE is defined). You normally do not call Step yourself unless you are building a custom integration.

Fluid Simulation Manager

Simulation control

FluidSimulationManager.simulations          // List<FluidSimulation> of all registered sims
FluidSimulationManager.globalTimeScale      // float multiplier for all sim time (script-only)
FluidSimulationManager.Step(deltaTime, maxSteps)
FluidSimulationManager.MarkSettingsChanged(bool changed)
FluidSimulationManager.RequestObstacleUpdate(bool changed)

Step advances every registered simulation, runs solid-to-fluid coupling on Fluid RigidBody instances, and updates cull/pause state from active game cameras. MarkSettingsChanged and RequestObstacleUpdate broadcast to all simulations when shared settings or obstacle geometry change at runtime.

Adding fluid

AddFluid(Vector3 worldPos, Vector2 size, float amount, float falloff, int layer, float timestep)

Adds fluid in a circular region at the specified world position and size. layer selects the fluid layer index. falloff controls the radial gradient. timestep is the delta time for this application (typically Time.deltaTime).

Applying flow and forces

ApplyFlow(Vector3 worldPos, Vector2 direction, Vector2 size, float strength, float falloff, float timestep)
ApplyFlowVortex(Vector3 worldPos, Vector2 size, float innerStrength, float outerStrength, float timestep)
ApplyForce(Vector3 worldPos, Vector2 direction, Vector2 size, float strength, float falloff, float timestep, bool splash)
ApplyForceVortex(Vector3 worldPos, Vector2 size, float strength, float falloff, float timestep)
ApplyForce(Texture texture, float strength, float timestep)

These mirror Fluid Modifier Volume behaviors programmatically. Flow methods write to the velocity field; force methods displace the height field. Set splash to true on ApplyForce for an outward radial impulse instead of a directional push. The texture overload applies a red-channel height/force mask in simulation UV space.

Sampling the simulation

Height & velocity

bool GetHeight(Vector3 worldPos, out Vector2 heightData)
bool GetHeightLayer(Vector3 worldPos, out Vector2 heightData, out int layer)
bool GetHeightVelocity(Vector3 worldPos, out Vector2 heightData, out Vector3 velocity)

Samples height and/or velocity at the specified world space position when inside a simulation’s bounds.

• heightData.x contains the total height in world space, including the height of the underlying terrain.
• heightData.y contains depth of the fluid in relation to the underlying terrain.
• velocity contains the fluid velocity in world space.
• GetHeightLayer also returns the dominant (highest) fluid layer index at that point.

Returns false when no simulation contains the position or no valid data is available.

Normals

bool GetNormal(Vector3 worldPos, out Vector3 normal)

Samples the world-space surface normal at the specified position.

Distance field

bool GetNearestFluidLocation2D(Vector3 worldPos, out Vector3 fluidLocation)
bool GetNearestFluidLocation3D(Vector3 worldPos, out Vector3 fluidLocation)

Samples the fluid distance field to find the nearest location containing fluid.

• 2D returns the nearest XZ location from the distance field; Y is copied from worldPos.y. Use this when you will sample other data at that horizontal location.
• 3D returns the nearest location including the fluid surface height. Useful for placing audio sources or markers directly on the water line.

Example

This script places a GameObject containing an AudioSource at the nearest fluid location relative to the object. Attach it to a camera or player.

public class FluidFinder : MonoBehaviour
{
    public GameObject audioSource;

    void Update()
    {
        FluidFrenzy.FluidSimulationManager.GetNearestFluidLocation3D(transform.position, out Vector3 location);
        audioSource.transform.position = location;
    }
}

Creating simulations, modifiers, and obstacles

FluidSimulationManager is the query and one-shot brush API. To spawn persistent objects (the same types the Scene View toolbar places), call Create on the component types. These methods work in play mode and in the editor. Created components register themselves in OnEnable, so every active simulation picks them up.

Simulations

FlowFluidSimulation sim = FluidSimulation.Create(
    settings, position, Quaternion.identity, terrain);

sim.AddFluidLayer<FluidFlowMapping>();

Create without a type argument uses Flow. Flux still works through FluidSimulation.Create<FluxFluidSimulation>(...).

settings must be assigned before the simulation can Init (that happens from Start, or call Init yourself if you need GPU resources the same frame). terrain is optional and is passed to SetTerrain (Unity Terrain, SimpleTerrain, Texture2D, or MeshCollider).

Surfaces

You still need a material. These methods only spawn and wire the renderer.

WaterSurface.Create(sim, waterMaterial, flowMapping);
LavaSurface.Create(sim, lavaMaterial, flowMapping, sim.transform, "Fluid Renderer");

Pass parent as null (or omit it) to add the component on the simulation GameObject. Pass a parent transform to spawn a child renderer.

In-memory settings

At runtime, create layer or simulation settings without writing assets:

FoamLayerSettings foam = FluidSettingsFactory.Create<FoamLayerSettings>(s => { /* optional */ });
FoamLayerSettings copy = FluidSettingsFactory.Duplicate(existingAsset);

Extension layers

Prefer these over raw AddFluidLayer when you need settings assigned in one call:

sim.AddFoamLayer(existingFoamSettings);
sim.AddFlowMapping(configure: s => s.flowMappingMode = FluidFlowMapping.FlowMappingMode.Static);
sim.AddWetnessLayer();
sim.AddErosionLayer();
sim.AddTerraformLayer();
sim.AddParticleGenerator(generator => { /* tune cascades, materials, etc. */ });

Pass null for settings to get a new in-memory instance from FluidSettingsFactory.

Terraform terrain and simulation

TerraformTerrain ground = TerraformTerrain.Create(
    position, terrainMaterial, Vector2.one, new Vector2Int(512, 512), parent);

FlowFluidSimulation sim = FluidSimulation.CreateTerraformSimulation(
    ground, waterMaterial, lavaMaterial, initSimulation: true);

// Or with Flux:
FluidSimulation.CreateTerraformSimulation<FluxFluidSimulation>(
    ground, waterMaterial, lavaMaterial);

CreateTerraformSimulation adds dual-layer fluid settings (or uses your settings asset), foam, static flow, TerraformLayer, and water/lava child surfaces. Pass null for a material to skip that surface.

Editor presets

In the editor, FluidSimulationMenu still writes settings assets and default materials. Call the same methods the GameObject menu uses:

FluidSimulationMenu.CreateWaterSimulation(terrainObject);
FluidSimulationMenu.CreateLavaSimulation(terrainObject);
FluidSimulationMenu.CreateWaterWorldSimulation(terrainObject);
FluidSimulationMenu.CreateTerraformSimulation(terraformTerrainObject);

Those wrappers create a Flow simulation. Pass Flux types to the generic overloads if you still need that solver.

Use FluidSimulation.Create at runtime when you already have settings and a material. Use the menu presets when you want a new authored sim in the scene.

Fluid modifiers

FluidModifierVolume.CreateSource(position, rotation, size, strength, layer);
FluidModifierVolume.CreateFlow(position, rotation, size, strength);
FluidModifierVolume.CreateForce(position, rotation, size, strength);
FluidModifierVolume.CreateVortex(position, rotation, size);

Yaw of rotation sets flow and force direction. After create, change the public sourceSettings / flowSettings / forceSettings fields as needed.

Terrain and terraform brushes

TerrainModifier.Create(position, rotation, size, strength, layer, splat);
TerraformModifier.Create(position, rotation, size);

TerrainModifier needs an ErosionLayer on the simulation. TerraformModifier needs a TerraformLayer.

Obstacles

FluidSimulationObstacle.CreateBox(position, rotation, size);
FluidSimulationObstacle.CreateSphere(position, rotation, radius);
FluidSimulationObstacle.Create(shape, position, rotation, size);

Shape helpers also exist for cylinder, ellipsoid, wedge, hex prism, cone, and capsule. Changing an obstacle at runtime still goes through FluidSimulationManager.RequestObstacleUpdate when you edit it by hand; Create already registers the new object.

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