ANR 3D Fire Simple

The engine, Bullet Time, the disk cache, simulation detail and quality, the start frame and the simulation boundary.

Engine

Fire EngineButtonfireEngine

Start the native GPU engine. Loading progress is shown during first evaluation. Click again to stop and free GPU memory. New nodes start stopped.

StatusStatusbackendInfo

What the engine is doing: stopped, loading, simulating, paused at a frame or freed while idle, plus messages about detail it had to reduce to fit the graphics card's memory, and errors.

Bullet Time

Bullet TimeCheckboxbulletTime

Freezes the simulation at the Freeze at frame. The camera, the volume transform, the lights and the look keep following the timeline, so you can fly around the frozen fire. Holding a frame costs no simulation time. Ticking it freezes at the current frame. Animate it off to let the simulation go on. Works live and on Read cache.

Default: off

Freeze atSliderbulletFrame

The simulation frame Bullet Time holds. Before it the simulation plays normally; from it on the fire stays still. Animatable.

Default: 1

Cache

Generate AutofillButtonanrCacheAutoFill

Create a new node-type/footage_letter_4digits folder on every click, then stop. Previous caches are kept. Enter a folder to choose a custom base.

Fills Cache folder with a new, uniquely named folder for this node: inside the folder you typed there or, when it is empty, next to the saved script (save the script first). Every click makes another folder; old caches stay.

Cache folderFilecacheFolder

Required for Build / rebuild cache: nothing is written until it is set. Each build writes a new cache_... folder here; older builds are never deleted. Use a local NVMe folder, about 1.3 GB per 100 frames. Legacy OpenCL Cache mode also keeps its .anrsim files here.

Default: empty

Cache to frameSlidercacheLast

Last frame Build / rebuild cache simulates and saves. 0 (or any frame not after the start frame) uses the end of the timeline, and that frame is written here when you build. The cache starts at the start frame.

Default: 0

After last frameMenucacheAfter

What plays after the last cached frame: that frame held still (render-only detail and distortion stand still too), or nothing.

Default: Hold last frameOptions: Hold last frame Empty

Build / rebuild cacheButtonbuildCache

Simulates from the start frame to Cache to frame on the GPU, with a progress bar and Cancel, and saves every frame into a new folder inside Cache folder. When it finishes, Read cache turns on and Fire Engine stops (its GPU memory is freed). Cancel, or a failure, deletes only the new folder: the cache being read stays. NVIDIA Flow only.

Read cacheCheckboxcacheOnly

Plays the saved cache: no simulation, no Fire Engine and no upstream evaluation of the simulation inputs. It is saved with the script, so a reopened script just plays. Live on a cache: the Look, Light and Render settings (layers, detail, distortion, smoothing, quality), surfaces and holdouts, and the view and placement when Simulation bounds is Unbounded and Simulation scale is 1. Emission, dynamics, forces, collisions, resolution, start frame, the explosion's burst and preset, and view or placement with Camera frame bounds need Build / rebuild cache: the status line says so after such an edit. Upstream picture changes always need a rebuild. Off: back to the live engine.

Default: off

Cache statusStatuscacheStatus

What the disk cache holds, which frame plays, and whether settings changed since the last build.

Detail & playback

Simulation detailSliderresolution

Simulation voxels along the longest image dimension, 24 to 512. Independent of output pixels: use a lower voxel count for HD/4K images. Flow may reduce effective detail to fit its memory budget; see engine status.

Default: 192

Depth resolutionSliderdepthCells

Depth scale in voxels. Together with Source thickness this sets emission depth. Flow grows sparse space around the plume; this is not a fixed container boundary.

Default: 80

Simulation resolutionMenuprocessingResolution

Scale simulation detail and depth only. Half divides each dimension by 2; Quarter by 4 (minimum 8 cells). Changes rebuild the simulation. Source framing and world speeds are preserved within voxel rounding. Render resolution is independent.

Default: FullOptions: Full Half Quarter

Render resolutionMenurenderResolution

Render at full, half or quarter width and height, then upscale beauty and layers to comp size. Does not change the simulation or require re-simulation. Preview quality can further limit render size and shading.

Default: FullOptions: Full Half Quarter

start frameSliderstartFrame

The volume is empty at this frame.

Default: 1

GPU schedulingMenugpuScheduling

Responsive leaves GPU time for the desktop. Maximum speed removes deliberate pauses and uses larger batches; desktop interaction may slow while calculating. Simulation quality is identical.

Default: ResponsiveOptions: Responsive Maximum speed

Reset simulationButtonresetCache

Throws away the live simulation and frees its GPU memory; the next render simulates again from the start frame. Fire Engine stays on.

Render qualityMenurenderQuality

Preview changes rendering only. Simulation resolution, depth, substeps, source sampling, dynamics and collisions stay at your settings. Flow uses an image up to 320 pixels wide/tall with smooth cubic volume sampling, skipping post detail, extra smoothing, internal fire light, environment/key shadows and extra layers. Render restores full shading and layers using the same live simulation. Switching modes does not re-simulate.

Default: RenderOptions: Preview Render

Simulation boundary

Simulation boundsMenusimulationBounds

Flow: Camera frame limits active sparse blocks to the current camera and volume placement, plus padding. Supports orthographic and perspective views. Off-frame smoke is discarded and cannot return. Camera and placement edits re-simulate in this mode. Unbounded preserves off-frame smoke and makes camera edits render-only. No opacity culling: all depths inside the camera near/far planes can contribute.

Default: Camera frameOptions: Unbounded Camera frame

Frame padding (%)SliderframePadding

Extra simulation space on each side of the camera frame. 5 keeps a small off-screen buffer for motion, shadows and internal fire light. 0 clips at sparse-block precision. Changing this re-simulates.

Default: 5

Sparse cleanup

Faint smoke cutoffSlidersmokeCutoff

Flow: retire whole sparse blocks below this simulation smoke density. 0 restores original cleanup, 0.002 is gentle, 1 is aggressive and can remove dense visible smoke. Typed values can exceed the slider. This is not screen opacity or a per-voxel clipping filter. A block stays while needed by an emitter, a neighbor, or smoke above the threshold; faint voxels inside surviving blocks remain. A short retirement delay applies. Changes re-simulate.

Default: 0.002

How the alpha emits: smoke, heat and fuel, depth and thickness, the tilt and pivot of the emitter plane, the source holdout and source velocity.

Emission

Smoke amountSlideremitSmoke

Smoke emitted from Source alpha.

Default: 0.65

HeatSlideremitTemperature

Heat emitted with the fuel.

Default: 1

FuelSlideremitFuel

Fuel emitted for combustion.

Default: 0.7

Depth & scale

Simulation scaleSliderdepthScale

Flow: enlarge and move ONLY the emitter before simulation. 2 doubles its size and distance from the camera. Automatic uses a consistent Perspective projection at every scale. FireSmoke compensates the current Orbit and volume Position/Scale to preserve source framing. Source anchoring makes these view edits re-simulate when scale differs from 1, even Unbounded. Voxel size, gravity, burn time and eddy sizes stay unchanged. Larger sources may trigger sparse coarsening; sources thinner than a voxel can be lost. Existing fluid, collisions and receiving surfaces are not transformed.

Default: 1

Position ZSlideremitterZ

Emitter center as a fraction of domain depth: 0 back, 1 front.

Default: 0.5

Source thicknessSlideremitterDepth

Emitter thickness as a fraction of domain depth.

Default: 0.22

Source orientation

Source rotation XSlidersourceRotateX

Tilt the alpha emitter in 3D, before simulation. -90 makes a horizontal floor facing upward; 0 is a front-facing wall. Gravity and existing smoke stay in world space. Flow only; changes re-simulate.

Default: 0

Source rotation YSlidersourceRotateY

Turn the emitter into a side wall. 90 turns its normal toward positive X. XYZ rotation order; affects only new emission.

Default: 0

Source rotation ZSlidersourceRotateZ

Rotate the source in its image plane, in degrees. Applied after X and Y.

Default: 0

Pivot XSlidersourcePivotX

Fixed rotation pivot in the source image: 0 left, 1 right. Place this on the source to keep that point anchored while tilting. It does not follow changing alpha bounds.

Default: 0.5

Pivot YSlidersourcePivotY

Fixed rotation pivot: 0 bottom, 1 top of the source image. Pivot depth uses Position Z. Source thickness follows the tilted plane.

Default: 0.5

Normal speedSlidersourceNormalSpeed

Extra emission speed perpendicular to the source plane, in voxels/frame. Positive points toward the camera at zero rotation, upward at X=-90. Velocity X/Y/Z remain world-space additions. 0 disables this extra velocity.

Default: 0

Keep mask alignedCheckboxsourceKeepMask

Project the alpha onto the rotated emitter so its camera footprint stays aligned. Near edge-on views or a plane crossing the camera cannot preserve the whole mask; adjust tilt/pivot if reported. Off rotates the mask with the plane.

Default: on

Show source planeCheckboxsourceGuide

Viewer-only guide. Rotation rings commit one undoable edit on release; Escape cancels. Does not render into the image.

Default: off

Show source rotation gizmoCheckboxsourceGizmo

Viewer-only guide. Rotation rings commit one undoable edit on release; Escape cancels. Does not render into the image.

Default: off

Source holdout

Source occludes fire / smokeCheckboxsourceOcclude

Use Source alpha as a depth-aware holdout at the emitter plane. Hides fire/smoke behind it, including layers. Soft alpha is respected. Render-only.

Default: off

Source motion

Velocity YSlideremitVelocityY

Upward source velocity in voxels per frame.

Default: 1.4

Velocity XSlideremitVelocityX

Additional source velocity in voxels per frame.

Default: 0

Velocity ZSlideremitVelocityZ

Additional source velocity through depth, in voxels per frame.

Default: 0

Follow source motionSliderinheritMotion

Transfer estimated source translation into the fluid. Uses alpha center motion and emitter Z; 0 disables inheritance.

Default: 1

How the gas moves: rise, turbulence, edge disturbance, flame breakup, burning and fading.

Rise & speed

buoyancySliderbuoyancy

Lift from hot gas.

Default: 1.6

smoke weightSlidersmokeWeight

Downward force from smoke density.

Default: 0.08

time scaleSlidertimeScale

Simulation time advanced per timeline frame.

Default: 1

Shape & edge detail

seedSliderseed

Phase of the 3D turbulence.

Default: 1

turbulenceSliderturbulence

Three-dimensional curl forces in the simulated flow.

Default: 1.8

Eddy sizeSliderturbulenceSize

Requested eddy scale in density voxels. Flow smoothly widens under-resolved eddies to fit its coarser velocity grid, avoiding grid-scale force patterns.

Default: 16

Edge disturbanceSliderdisturbance

Flow: fine motion concentrated at smoke edges, plus gentle bulk eddies. Larger values continue increasing strength; high values can disperse the plume. Typed values can exceed the slider.

Default: 5

Edge sizeSliderdisturbanceSize

Fine edge eddy scale in density voxels. Flow transports smoke and heat together on the fine grid; very small wavelengths are smoothly limited to avoid voxel aliasing.

Default: 3

Flame breakupSlidershredding

Fine rotational forces restricted to burning regions.

Default: 0.65

Burn & fade

burn rateSliderburnRate

Rate at which hot fuel burns.

Default: 0.65

coolingSlidercooling

Heat loss per simulation frame.

Default: 0.07

Smoke dissipationSliderdissipation

Smoke loss per simulation frame. Higher values fade smoke faster; 0 disables this fading. Changes re-simulate.

Default: 0.012

burn expansionSliderexpansion

Outward gas expansion caused by combustion.

Default: 0.08

flame lifetimeSliderflameLifetime

Decay time of luminous flame in simulation frames.

Default: 1.5

Wind with gusts, drag, and a local push, attract, repel, vortex or turbulence force, in a box or everywhere.

Viewer

Show force guidesCheckboxforceGuide

Viewer-only bounds and falloff for the local force, its direction, and a wind arrow. Whole simulation forces have no finite boundary. Never rendered.

Default: off

Wind

Wind speedSliderwindSpeed

Flow: target air speed in authored voxels per simulation frame. Typed and animated values above the slider range continue increasing the wind; there is no 20-unit strength cap. Acts on existing fluid, not just the emitter. 0 disables wind. Direction is normalized. Changes re-simulate.

Default: 0

Direction XSliderwindX

Wind direction in simulation space. Positive X is right in the default view. An all-zero direction disables wind.

Default: 1

Direction YSliderwindY

Wind direction: positive Y is up in the default view.

Default: 0

Direction ZSliderwindZ

Wind direction: positive Z is toward the default camera.

Default: 0

Gust amountSliderwindGust

Smooth variation around Wind speed. 0 is steady; 1 varies between near calm and up to twice the base speed. Deterministic from the simulation seed.

Default: 0

Gust speedSliderwindGustSpeed

Rate of wind variation per timeline second (24-frame simulation timebase). 0 freezes the gust pattern. Strength remains controlled by Wind speed.

Default: 1

Drag

DragSliderforceDrag

Global velocity damping per simulation second. 0 off. Higher values slow existing motion; they do not remove smoke or heat.

Default: 0

Local force

Force strengthSliderforceStrength

Acceleration in authored voxels per simulation frame squared. Negative values reverse push, attraction, repulsion or vortex rotation. 0 disables the local force. Changes re-simulate.

Default: 0.25

Local forceMenuforceType

Affects existing simulated fluid. Changes rebuild simulation. Wind and drag can act at the same time; forces run only on allocated cells and do not create smoke.

Default: OffOptions: Off Push Attract Repel Vortex Turbulence

ScopeMenuforceScope

Limit the local force to a positioned box with smooth edge falloff, or affect all active fluid.

Default: BoxOptions: Whole simulation Box

Force position & size

Center XSliderforceX

Force center: 0 left, 1 right of the reference simulation domain. Coordinates belong to the simulation, before volume placement and camera match-move.

Default: 0.5

Center YSliderforceY

Force center: 0 bottom, 1 top of the reference domain.

Default: 0.5

Center ZSliderforceZ

Force center: 0 back, 1 front of the reference depth.

Default: 0.5

Box widthSliderforceSizeX

Full X extent of the local force box in longest-frame units. Used when Scope is Box.

Default: 0.6

Box heightSliderforceSizeY

Full Y extent of the local force box in longest-frame units.

Default: 0.6

Box depthSliderforceSizeZ

Full Z extent of the local force box in longest-frame units.

Default: 0.6

Edge softnessSliderforceFalloff

Fraction of the force box used for smooth falloff toward its boundary. 0 is a hard boundary; 1 fades across the whole box.

Default: 0.5

Push / vortex axis

Axis XSliderforceAxisX

Direction for Push, or spin axis for Vortex. The vector is normalized; all-zero disables those two modes.

Default: 0

Axis YSliderforceAxisY

Push direction or vortex spin axis Y.

Default: 1

Axis ZSliderforceAxisZ

Push direction or vortex spin axis Z. Use (0,0,1) for a swirl in the image plane.

Default: 0

Force turbulence

Noise sizeSliderforceNoiseSize

Turbulence force wavelength in authored voxels. Small sizes are limited by the velocity grid to avoid grid artifacts.

Default: 16

Noise speedSliderforceNoiseSpeed

Evolution rate of the local turbulence force per timeline second. Uses the simulation seed.

Default: 1

Smoke density and colour, flame brightness and colours (blackbody or a custom gradient), without re-simulating.

Smoke

smoke densitySlidersmokeDensity

Flow render density multiplier. Increase for thick soot without re-simulating; combine with a dark smoke color.

Default: 0.6

AbsorptionSlideropacity

Absorption along real paths through the smoke.

Default: 5

smoke colorColoursmokeColor

Colour of the smoke. Dark values give sooty black smoke, still lit by the fire.

Default: 0.2399999946 0.2450000048 0.25

Fire

fire saturationSliderfireSaturation

Flow flame color saturation; 0 is neutral and 1 preserves the chosen colors.

Default: 1

fire color biasSliderfireColorBias

Flow color-gradient distribution. Above 1 favors the cool flame color; below 1 favors the hot color.

Default: 2.33

Flame brightnessSliderfireIntensity

Emission integrated within the smoke volume.

Default: 6.4

fire colorMenufireColorMode

Blackbody uses the cool/hot temperatures in Kelvin. Custom gradient uses the three color swatches below. Both share saturation and color bias.

Default: BlackbodyOptions: Blackbody Custom gradient

Flame colors

Cool temperature (K)SliderkelvinMin

Blackbody color at the low end of the temperature range.

Default: 1000

Hot temperature (K)SliderkelvinMax

Blackbody color at the high end of the temperature range.

Default: 5100

custom coolColourfireCool

With fire color set to Custom gradient: the colour of the coolest flame, at the tips.

Default: 1 0.02500000037 0.002000000095

custom midColourfireMid

With Custom gradient: the colour in the middle of the flame's temperature range.

Default: 1 0.2199999988 0.009999999776

custom hotColourfireHot

With Custom gradient: the colour of the hottest flame, in the core.

Default: 1 0.8999999762 0.5500000119

Temperature mapping

temperature rangeSlidertemperatureRange

Simulation temperature mapped to the hottest flame color.

Default: 1.25

Sky light, the fire's light inside the smoke, ambient and key light with its direction, and the environment map.

Sky Light

Sky intensitySliderskyIntensity

Smoke illumination from the upper sky dome. Density along each light ray occludes the sky. 0 is off and preserves previous renders; render-only.

Default: 0

Sky colorColourskyColor

Colour of the sky light set by Sky intensity.

Default: 0.6999999881 0.8000000119 1

Sky samplesSliderskyLights

Directions over the sky dome (Flow). Higher values soften directional sampling at extra render cost. Does not re-simulate. Legacy uses six directional lobes.

Default: 8

Internal fire light

Fire illuminationSliderfireLight

Flow: colored flame light propagated through a sparse volume with absorption and approximate multiple scattering. Strength is independent of visible flame brightness.

Default: 0.9

Light penetrationSliderscattering

Diffuse light penetration into smoke. Flow reduces effective absorption when propagating multiply scattered fire light; this is a diffusion approximation.

Default: 0.7

Light spreadSliderfireLightRadius

Spread of diffuse fire illumination as a fraction of domain width.

Default: 0.1

Scene lighting

Ambient fillSliderambient

Environment illumination.

Default: 0.18

key lightSliderkeyLight

Directional light with volume self-shadowing.

Default: 1.4

ambient occlusionSliderambientOcclusion

Shadows within the volume under environment lighting.

Default: 1

Light direction

key direction XSliderlightX

Direction toward the light.

Default: -0.6

key direction YSliderlightY

Direction toward the light.

Default: 0.8

key direction ZSliderlightZ

Direction toward the light.

Default: 0.7

forward scatterSlideranisotropy

Directionality of scattering: 0 is isotropic, positive favors backlighting.

Default: 0.15

Environment map

use environmentCheckboxuseEnvironment

Connect a linear latitude-longitude HDR/EXR image to Environment. Flow adds broad ambient color; environment rotation and directional map lighting require Legacy OpenCL. Alpha is ignored and the background stays transparent.

Default: on

intensitySliderenvironmentIntensity

Brightness of the connected linear latitude-longitude environment map.

Default: 1

exposureSliderenvironmentExposure

Environment exposure in stops; +1 doubles the light.

Default: 0

rotation YSliderenvironmentRotation

Rotate environment lighting around the volume's vertical axis, in degrees.

Default: 0

Output, render-time detail and distortion, smoothing, 3D placement, the view and render sampling.

Output

outputMenuoutput

Select the RGBA render: beauty, fire or smoke. Smoke includes illumination from fire. This native node does not create named EXR layers; write each selection separately. Depth requires Legacy OpenCL.

Default: beautyOptions: beauty fire smoke depth

Post-sim detail

Detail strengthSliderdetailAmount

Flow render-only procedural volume detail. Fire Simple strength increases linearly, including above the slider range. 0 disables procedural detail; no re-simulation.

Default: 10

Detail sizeSliderdetailSize

Detail wavelength in authored density voxels. Smaller creates finer detail. This is volume-space shading detail, not advected high-resolution simulation.

Default: 2.92

Post-sim detailMenudetailMode

Flow: add procedural 3D detail to the existing volume and use finer ray sampling. Does not re-simulate, allocate an up-res grid, or recover missing physics. 4x costs more rendering time. Start with 2x and strength 0.5.

Default: 4x samplingOptions: Off 2x sampling 4x sampling

Post-sim distortion

Distortion amountSliderdistortionAmount

Render-only 3D displacement in authored voxels. Fire, smoke and alpha warp together. 0 restores the original image exactly; no re-simulation. Larger values cost more ray sampling. Lighting fields move with the material; shadows are not re-solved. Surface passes and point snapshots stay undistorted.

Default: 0

Feature sizeSliderdistortionSize

Distortion noise wavelength in authored voxels. Larger creates broad rolling deformation; smaller creates fine edge breakup. Does not change simulation.

Default: 16

Animation speedSliderdistortionSpeed

Continuous volume-noise evolution per simulation second. 0 freezes automatic evolution. Render-only.

Default: 0.5

EvolutionSliderdistortionEvolution

Offset the 3D distortion pattern. Animate this to change distortion without changing simulation time. Render-only.

Default: 0

Distortion seedSliderdistortionSeed

Select a different deterministic 3D distortion pattern. Independent of the simulation seed.

Default: 1

Smoothing

Extra smoothingSliderfilterWidth

Extra volume smoothing radius in voxels. 0 keeps the selected base reconstruction. Applies in Preview and Render without changing the simulation; larger values soften more voxel detail.

Default: 0

volume filterMenuvolumeFilter

Linear preserves more voxel detail. Smooth cubic uses positive B-spline reconstruction to soften voxel facets without sharpening rings. Filter width adds smoothing; 0 keeps the chosen base reconstruction. Flow honors both modes in Preview and Render. Legacy Preview uses linear sampling after its width filter.

Default: Smooth cubicOptions: Linear Smooth cubic

3D placement

ProjectionMenucameraProjection

Flow: Automatic consistently uses Perspective, including at Simulation scale 1, to avoid shifting a source with depth when scale crosses 1. Explicit Orthographic cannot compensate apparent size with distance. FireSmoke source scaling also compensates current Orbit and volume placement; these edits re-simulate a scaled source even Unbounded. Position and Volume scale remain transforms of the finished volume.

Default: AutomaticOptions: Orthographic Perspective Automatic

Position XSlidervolumeX

Move the whole fire/smoke volume in world X. 1 equals the longest frame dimension at the reference plane. Does not move the emission source inside the simulation.

Default: 0

Position YSlidervolumeY

Move the whole volume in world Y. Positive moves up in the default view.

Default: 0

Position ZSlidervolumeZ

Move the whole volume in depth. In the default view positive is toward the camera, negative is farther away. Perspective makes closer volumes appear larger; Orthographic preserves apparent size. World axes rotate on screen when you orbit.

Default: 0

Volume scaleSlidervolumeScale

Uniform 3D scale about the simulation center. Independent of Position Z: enlarge a distant volume or shrink a nearby one. Keeps the simulation and internal shading in local coordinates; this is placement, not a physical re-scaling of fluid dynamics.

Default: 1

View

orbit YSliderviewYaw

Rotate the view around the actual volume, in degrees.

Default: 0

orbit XSliderviewPitch

Tilt the orthographic view, in degrees.

Default: 0

zoomSliderviewZoom

Camera zoom in either projection. With Camera frame bounds this changes the simulated region.

Default: 1

Render sampling

Ray step sizeSliderrayStep

Distance between ray samples in voxels. Lower gives finer rendering.

Default: 0.75

shadow samplesSlidershadowSteps

Samples through the volume toward the key light.

Default: 32

Solver backend, substeps and the legacy disk cache mode.

Solver

Solver backendMenusolverBackend

Flow runs a native sparse Vulkan solver and renderer. This preview has live GPU state, source motion, orbit, filtering, blackbody shading and beauty/fire/smoke passes. Legacy OpenCL is needed only for depth and the old cache mode. Switching backend resets the live simulation.

Default: NVIDIA Flow Vulkan (preview)Options: Legacy OpenCL NVIDIA Flow Vulkan (preview)

Simulation sampling

substepsSlidersubsteps

Minimum fluid/source steps per frame. Fast translating sources automatically increase this, up to 32.

Default: 3

source samplesSlidersourceSamples

Nuke rounds direct OFX source fetches to whole frames. Native Fire Simple fetches frame endpoints and transports/interpolates their masks through simulation substeps. Subframe-only source changes are not available without a retime wrapper.

Default: 1

pressure iterationsSliderpressureIterations

Pressure solve quality. This preview uses iterative projection.

Default: 60

Legacy disk cache

cache modeMenucacheMode

Off is the interactive default and performs no disk-cache transfers. Legacy OpenCL: Read/write saves full state each frame and can slow simulation; Playback reads baked frames without simulation. Legacy OpenCL only. Flow uses Build / rebuild cache below.

Default: OffOptions: Off Read/write Playback

Collision and holdout from the Interaction alpha, and the built-in ground.

Interaction

Motion transferSlidercollisionMotion

Transfer Collision alpha translation and animated Collision depth into fluid velocity. 1 follows the moving solid; 0 gives the old stationary-wall response. Subframe masks are transported between samples. Alpha centroid estimates translation: separate moving objects, rotation and deformation are approximate. Changes re-simulate.

Default: 1

Interaction collisionCheckboxsurfaceCollisionEnabled

Use the Interaction alpha as a solid object. Alpha above 0.5 is solid. Thickness sets extrusion; animated movement transfers velocity. Changes re-simulate.

Default: off

Interaction occludes fire / smokeCheckboxsurfaceOcclude

Depth-aware holdout from Interaction alpha. Keeps volume in front and hides volume behind, including layers. Soft alpha is respected. Render-only.

Default: off

Interaction thicknessSlidersurfaceThickness

Fraction of simulation domain depth. Minimum effective thickness is one voxel; only used with Interaction collision enabled.

Default: 0.05

Interaction positionSlidersurfacePosition

0 behind with a gap; 1 touching the back; 2 in the middle; 3 in front. Typed values extend farther behind or in front. Collision edits re-simulate, occlusion alone changes rendering.

Default: 1.2

Ground

Enable groundCheckboxgroundEnabled

Built-in finite solid floor. No input needed. Position/rotation are in simulation space before volume placement and camera match-move. Changes re-simulate when collision is on.

Default: off

Ground collisionCheckboxgroundCollision

Block and redirect the simulated fluid at the ground. Flow only.

Default: on

Ground occludes fire / smokeCheckboxgroundOcclude

Hide volume behind the solid floor, including fire and smoke passes. Render-only.

Default: on

Show ground guideCheckboxgroundGuide

Wireframe in the Viewer while node controls and Viewer overlays are open. Never included in renders.

Default: on

Show ground rotation gizmoCheckboxgroundGizmo

Drag RGB rotation rings in the Viewer. Commits on release; Escape cancels. Requires Enable ground.

Default: off

Ground position

Ground XSlidergroundX

Top surface center in simulation space: 0 left, 1 right of the reference frame.

Default: 0.5

Ground YSlidergroundY

Top surface height: 0 bottom, 1 top of the reference frame. The solid extends below this surface.

Default: 0

Ground ZSlidergroundZ

Top surface center in depth: 0 back, 1 front of the reference simulation depth.

Default: 0.5

Ground rotation

Rotation XSlidergroundRotateX

Rotate the ground around its movable rotation anchor, in degrees.

Default: 0

Rotation YSlidergroundRotateY

Ground rotation in degrees; XYZ order.

Default: 0

Rotation ZSlidergroundRotateZ

Tilt the floor in the image plane, in degrees.

Default: 0

Ground pivot

Ground pivot XSlidergroundPivotX

Rotation anchor offset in longest-frame units. Use the white Viewer center handle to re-anchor while preserving the ground placement.

Default: 0

Ground pivot YSlidergroundPivotY

Rotation anchor offset in longest-frame units. Drag the center square to place the pivot in the Viewer.

Default: 0

Ground pivot ZSlidergroundPivotZ

Rotation anchor depth offset in longest-frame units.

Default: 0

Ground size

Ground widthSlidergroundWidth

Finite floor width in longest-frame units. 1 spans the longest frame dimension.

Default: 2

Ground depthSlidergroundDepth

Finite floor depth in longest-frame units.

Default: 2

Ground thicknessSlidergroundThickness

Solid thickness below the top surface, in longest-frame units. Use at least several simulation voxels to avoid leaks.

Default: 0.25

Turns the stored background track on or off.

Read camera motionCheckboxmotionEnabled

Use the stored track to stabilize source/interaction and match the rendered volume back to the shot. Uncheck to disable without deleting the track.

Default: off

Camera / track nodeTextmotionNode

Optional node path for a 3D Camera or image track. Overrides CameraMotion input. Clear to use the connected track. Only read when you click Read motion track.

Default: empty

Pick selected camera / trackButtonpickMotion

A button.

First frameNumbermotionFirst

No description.

Default: 1

Last frameNumbermotionLast

No description.

Default: 100

Reference frameNumbermotionReference

No description.

Default: 1

Samples per frameNumbermotionSamples

No description.

Default: 4

2D track directionMenumotionDirection

Auto recognizes Tracker stabilize modes and inverted Transform/CornerPin nodes. For an exported stabilization transform without an invert flag, choose Stabilize. Camera ignores this setting.

Default: AutoOptions: Auto Match-move Stabilize

Camera source distanceSlidermotionDepth

For a Camera input only: distance from the reference camera to a perpendicular source plane, in scene units. Re-read after changing. Not the volume Position or Simulation scale.

Default: 10

Read motion trackButtonreadMotion

A button.

Clear motion trackButtonclearMotion

A button.

Stored trackStatusmotionStatus

No description.