Sneak peek: Houdini 21

SideFX has released a sneak peek video showing the new features in Houdini 21, the next major version of its procedural 3D software for VFX, game development and motion graphics.

The company will announce more details next week at SIGGRAPH 2025, but below, you can see some of the highlights, from Neural Point Surfacing for liquids to the Otis organic tissue solver.

We’ve also compiled an (almost) complete list of all 300+ features covered in the video, which you can find at the end of the story.

Character rigging and animation: KineFX becomes production-ready
Houdini 21 is a wide-ranging update, adding new features throughout the core toolsets.

However, some of the most significant are to character work, where KineFX, SideFX’s procedural character rigging and animation toolset becomes officially production-ready.

The update extends its auto-rigging capabilities, with new auto-rig components for limbs, hands and feet; and adds the capability to build “complex facial rigs” with blendshape support.

Animators get an experimental new Motion Mixer for blending animations, with an NLE-style interface complete with tracks and clips, and native support for Houdini’s APEX framework.

It makes it possible to mix “arbitrary APEX rig controls, not only skeletal animation”.

CFX: new Otis organic tissue solver and Otto human character
Character FX (CFX) artists get Otis, a GPU-accelerated solver for organic tissues like muscles and fat, described as faster than the existing Vellum solver, with “FEM-level physical quality”.

A new muscle transfer system will make it possible to transfer “full muscle rigs and bone geometry” between characters.

In addition, Houdini 21 will ship with Otto, a “fully muscle- and tissue-rigged human”, and a Deform model trained on Otto’s muscle system.

That sounds like it’s along the lines of the ML Deformer in Maya, which uses machine learning to create a faster-processing approximation of complex character deformations.

FX: updates to the MPM solver and Neural Point Surfacing for liquids
Houdini 21 also extends the new Material Point Method (MPM) multi-material solver introduced in the previous release.

New features include debris emission for secondary particle simulations, and MPM Surface, a meshing toolset with UV preservation and support for surface tension.

The video also shows Neural Point Surfacing for liquid simulations – which, again, looks like it may use machine learning to create a faster-processing approximation of a more complex sim.

FX: AI-based upresing for Pyro simulations
Pyro, Houdini’s volumetric simulation system for effects like smoke and fire, also gets new machine learning features, in the shape of ML Volume Upres.

It uses AI to upres Pyro simulations, with the results described as “fast, accurate and frame-coherent”.

Vulkan viewport and Copernicus image-processing framework now production-ready
Two of the main experimental features introduced in recent versions of Houdini also become production-ready in Houdini 21.

The new Vulkan viewport introduced in Houdini 20 now has full parity with the legacy OpenGL viewport, and now runs on macOS via MoltenVK.

In addition, Copernicus, the new 2D and 3D image-processing framework introduced in Houdini 20.5 is now production-ready for “all uses except advanced compositing”.

It gets quite a few new features, too, including support for advanced noise types like Phasor and Bubble noise, and even complete new 2D Flow and 3D Sparse Pyro solvers.

Other new features
Other interesting new features in Houdini 21 include a new shot sculpting toolset, for making corrective adjustments to characters on a per-shot basis, and initial support for 3D Gaussian Splatting (3DGS) in Karma XPU, Houdini’s GPU-accelerated render engine.

At the foot of the story, you can find a full list of features shown during the sneak peek, both in the main video and the title crawl at the end.

By our count, there are well over 300 changes, including updates to the Procedural Dependency Graph (PDG), Houdini Engine and the SideFX Labs bonus tools.

Price, system requirements and release date
SideFX hasn’t announced a release date for Houdini 21 yet, but in recent years, its sneak peek videos have usually been posted around a month ahead of the public release.

You can find details of current pricing and system requirements in our story on Houdini 20.5.

Read more about Houdini on SideFX’s website
(No more information on Houdini 21 at the time of writing)

All of the new features listed in the Houdini 21 sneak peek

The end of the video includes a high-speed title crawl listing the changes in Houdini 21 in detail. It fades to black in the middle, making it impossible to read some of the bullet points, but below, we’ve reproduced those that can be seen.

Kudos to ILM Senior FX TD Yunus Balci whose initial transcription of the title crawl on the SideFX forum provided an invaluable starting point for this list: we’ve extended his transcript here.

KineFX: APEX-driven rigging and animation

Production-ready for all riggers and animators
Additional auto-rig components: for example, limb, hand, foot, neck, scapula, ulna
Spine rig component v3.0 with interactive squash and stretch and more
Enhancements to reverse foot, including rotational toe control
Fast, interactive and easy-to-use rig builder with viewport drag-and-drop
Ability to rapidly build complex facial rigs with blendshape support
Simplified procedural auto-rig component creation based on graph fusion
Updated Electra rig with twist joints, reverse foot, clavicle, bendable IK/FK
Fully rigged realistic human: Otto v1.0
Many enhancements to APEX graphs and APEX scripting
Fast in-place APEX cooking of SOP verbs, similar to compiled SOPs
Convenience nodes for converting KineFX characters to packed folders
Streamlined ragdoll configuration workflow
Ability to animate ragdoll stiffness, damping ratio, rest length and more
Revamped constraint system with support for multiple concurrent constraints
Soft and hard ragdoll tether constraints
Parent, Static and LookAt constraints
Automatic constraint offset controls
Option to create custom constraints and build on top of standard set
Ability to add keyframes to mirrored controls automatically
Full-body IK posing with high-level targets for streamlined animation
Ability to inherit animation layers from upstream APEX animation nodes
Hotkeys to grow and shrink a selection of controls
Unified and streamlined keyframe baking workflow
IK/FK switching
Playbar Ripple tool to move all keys before or after cursor location
Enhancements to selection sets: for example, rig control management and display
Hotkey-driven rig control pick-walking with topological heuristics
Ability to hide rig controls when scrubbing and dragging
Animatable rig control feedback: for example, shape and color
Posing with invisible controls: aka direct skin manipulation
GPU-accelerated skin and blend shape deformation in future production build
Customizable look-and-feel of standard 3D handles
Rewritten audio subsystem based on FFmpeg with smooth scrubbing
Scene Add Prop node options for animated and deforming geometry
Animation transfer with APEX Animation from Skeleton
Up to 6x faster panning in the animation Graph Editor
Completely redesigned Animation Catalog: aka pose library
Motion Mixer (beta) with tracks, clips, NLE-style GUI and native APEX support
Motion mixing of arbitrary APEX rig controls, not only skeletal animation
Fully featured APEX animation environment available as a Mixer effect
Built-in support for ML-driven skin deformation with custom training recipes
glTF importer for character, animation and skinned geometry
Countless UX improvements across the board

CFX

Otis: robust, GPU-accelerated organic tissue solver for muscle and tissue
Otis: FEM-level physical quality and faster than Vellum
Simultaneous, fully coupled muscle and tissue simulation
Robust volume-based muscle and tissue collisions immune to initial intersections
Muscle and tissue configuration nodes redesigned for ease of use
Re-engineered tissue mesh generation allowing for robust fat-muscle collisions
Otto: humanoid rig with bone geometry and full muscle and tissue system
Ability to transfer full muscle rigs and bone geometry between characters
Deform model trained on Otto’s muscle system
Real-time APEX animation of ML Deform-trained characters
ML Train Deform recipe to facilitate training with user data
Armature system for quasi-static muscle capturing, simulation and deformation
Armature Deform node designed for data training for ML deformation
Organic Deformer node to minimize tet mesh energy for improved accuracy
Muscle Deintersect node to remove small intersections
Ability to blend overall activation in Muscle Flex SOP
Automatic muscle-to-tension line matching and multiple lines per muscle
UI/UX enhanced Muscle Constraint Properties node
Muscle Tension Line Activate node for procedural and user-friendly activation
Muscle Auto Tension Lines for easy, procedural definition of tension lines
Muscle Adjust Volume to control muscle mass with collision support
Many functionality enhancements to Muscle Solidify
Remove Fat node to control how fat tissue influences muscle transfer
10x speedup of procedural fibre direction computation
3–4× faster tetrahedral conversion
GPU-accelerated edge relaxation with surface sliding support
GPU-accelerated delta mush
Fast grooming with Parallel Transport Along Geometry
Guide Clump Center to generate center lines of hair clumps
Guide Surface to generate triangle surfaces over hair grooms
Guide Fill to populate empty points on guide interpolation meshes
Guide Find Strays to identify and group stray hairs for downstream grooming

Geometry | Modelling | Environments

Powerful shot sculpting toolset with NLE-style GUI for character finaling
Elastic Deform, Plow and Planar sculpt brushes
Option to sculpt using surface distance falloff
Convenient in-node management of sculpt masks
Ability to extract geometry contours procedurally with frame coherence
Unsubdivide node to reduce the resolution of previously subdivided meshes
Improved Paint SOP performance with geometry groups
Enhanced Texture Mask Paint with respect to UDIMs, alpha and mask flattening
Bidirectional ray support and options for group transferring in Ray SOP
Ability to model branching curves as well as cutting and joining curves
Adaptive quad remeshing for improved results on organic geometry
Procedural and interactive edge flow control in quad remeshing
Support for the @ attribute syntax for vertex groups
Many enhancements to Poly Extrude SOP
Ability to un-overlap pieces of geometry identified by string or int attribute
Ability to use UV Fuse in compiled blocks for faster performance
Versatile UV map generation with UV Flatten from Points SOP
Topological sliding guided by curve references
Edge relaxation node to match reference geometry
Extrapolation enhancements to attribute filling
OpenCL topology bindings for half-edge attributes and tetmesh adjacency
OpenCL-accelerated attribute sorting
Multithreaded geometry sorting
Redesigned, COP-powered hydraulic terrain erosion with simplified controls
Option to output erosion sediment, flow and debris
Neural brush-based terrain generation with trained models in Content Library

Pyro | Crowds | RBD

Rich set of Pyro recipes such as thruster exhaust, fire portal and wispy smoke
Fast, accurate and frame coherent ML-based pyro upres node
ML Train Volume Upres recipe for user-specific scenarios
Gas Remap node to shift and scale a scalar volume field into new range
Gas Burn node to control flame field dissipation and emit smoke and heat
Enhanced turbulence controls in Pyro solver
Partitioning of large point clouds to execute efficiently on OpenCL devices
Ability to blend between animation clips based on crowd agent’s turn rate
Support for parent-child agent setups via crowd motion path toolset
Easy to use fracture-and-destruction system built into dynamic car rigs
Options for fans and propellers to support spinning parts in motors
Easier to have vehicles jump off the ground at specified locations
Bullet solver v3.25

MPM

Multi-faceted enhancements to post-simulation pipeline
Surfacing node to efficiently generate render-ready geometry
Surface tension support for realistic liquid behaviour
Debris emission for secondary particle simulations
Deterministic particle-to-grid option for reproducible results and speed
Ability to emit particles on top of existing particles to fill MPM container
Support for the ‘age’ point attribute in MPM Source
Ability to add upper and lower padding to MPM container
Dedicated nodes for streamlined post-simulation processing
Specialized post-simulation nodes for stiff material destruction: for example, metal
Updated recipes to support the new post-simulation pipeline
Auto-sleep mechanism for faster simulation and sag-free initialization
Per-voxel variable thickness and friction support in collisions
Highly accurate deforming colliders
Dedicated MPM shelf

Neural Point Surfacing

[Not legible during the title crawl]

Solaris

[Not legible during the title crawl]

Karma CPU and XPU

[The initial bullet points are not legible during the title crawl]

Faster and more memory-efficient rendering of subdivision surfaces
Dedicated whitewater shader
Direct rendering of OpenVDB points
Accelerated motion blur rendering of VDB volumes
Volume shadow step rate control for better performance
Native support for integer and vector volumes
Support for USD colorSpace metadata on material parameters
Automatic exporting of basecolor AOV
More realistic hair rendering with combined use of melanin and attenuation
Fur rendering enhancements: GGX wetness and presets
Support for subsurface scattering (SSS) tracer sets: maximum of 4 on XPU
Ability to orient hextiles based on curve tangents
Automated way to invert alpha channels directly inside Karma
Improved/smoother rendering of isosurfaces
Ability to write out albedo AOV based on specific path or BSDF component
Accurate identification of lat-long, mip-mapped and tiled OpenEXR textures
Dicing enhancements to improve rendering of scenes with large displacement
Stencil map support for a fast way to control polygon visibility with ST coordinates
Synchronized nested dielectric priorities between CPU and XPU
CoordSys primitive discovery
OIDN denoiser 2.2.1
Ability to denoise with CPU only
Automatic switching to bucket mode when rendering deep images
Husk support for render pass specification
Render stats and Husk information included in deep image metadata
Support for custom metadata in render products and AOVs with Husk
Improved handling of deep image RGBA channels in Husk
Ability to assign default render delegate to Husk
Husk auto-tiling, including deep image support
Husk support for viewport render delegates such as Vulkan
CPU: GPU-accelerated texture baker
CPU: high-quality non-photorealistic (NPR) outline generation
XPU: precompiled render kernels for faster startup
XPU: optimized compilation of user-defined shaders
XPU: volumetric light support
XPU: uniform volume rendering that matches the CPU renderer
XPU: support for partial opacity in conjunction with background holdouts
XPU: ability to prevent background holdouts from receiving shadows
XPU: support for shadow linking of up to four geometry subsets
XPU: ability to blend up to 16 MaterialX Standard Surfaces
XPU: support for string primvars
XPU: Multi-Importance sampling (MIS) compensation for noise reduction
XPU: ability to select specific Intel Embree and NVIDIA OptiX devices
XPU: initial support for 3D Gaussian Splats, with lots more to come

General UI | UX

Faster and fully redesigned node info in all supported OP contexts
Redesigned multi-parm UI/UX to allow interactive reordering and more
More consistent look and feel of guides and handles in all Houdini contexts
Recipe Builder subnet to preserve recipe content and capture settings in .hip
Forever’ playback mode to advance playbar indefinitely
‘Live Simulation’ mode to run simulations continuously regardless of playbar
Non-contiguous character matching in text editor autocomplete
[Ctrl]-clicking Reset Simulation to also clear the simulation cache
Flexible framework for binding hotkeys to actions
Support for binding key sequences to hotkey actions
Volatile hotkey symbols to toggle display options

PDG and TOP Task Management

ML Train Style Transfer to train data using two classes of images
ML Train OIDN node for training an OIDN denoising filter model
PDG Training Monitor panel for ML training visualization
Convenient one-node wrapper for GLTF ROP and ROP Fetch
Simplified file set preparation with Preflight node
Ability to import work items from an externally-defined TOP network
Ability to run Python script defined in an external .py file
Enhancements to Python scripting when cooking out of process
Attribute String Edit to modify string attributes based on defined filters
Attribute Classify to examine work items based on unique values
Easy importing of key/value attribute pairs into a dictionary
Partition by Frame option to filter input work items by their frame value
ProRes codec encoding on macOS with FFmpeg Encode Video
Ability to control root job verbosity with HQueue, Deadline and Tractor
Deadline Scheduler restored to scheduling work items as tasks by default

Houdini Engine | Plugins | Hqueue | Platforms

Houdini Asset Editor for Unreal
Unreal PCG integration with ability to use HDAs in PCG graphs
Unreal plugin performance optimizations
Houdini Engine plugin support for UE 5.5–5.6, Maya and 3ds Max 2026, Unity 6.0–6.1
Houdini Engine API: faster data transfer via optimized shared memory side channel
Houdini Engine API: Python bindings using Nanobind
Houdini Engine API: support for Copernicus
Unity plugin optimizations and UX improvements
Output Log and HDA panel in 3ds Max
Quality of life improvements to the 3ds Max plugin
HQueue option to control client permissions on job output files
Pattern matching in HQueue ROP and TOP nodes for client parameters
Easier HQueue ROP job command customization using XML-based format
Port to x86_64-v3 feature level for additional compile-time optimizations
Greatly reduced startup time on certain Windows systems
Greatly reduced filesystem activity when loading Houdini
Upgraded A/V encoders and decoders
Adherence to VFX Reference Platform CY2025
Qt 6.5 default and 5.15 separate download
Python 3.11 only

SideFX Labs

Project Dryad: advanced biome toolset now in beta
Built-in presets and test geometries for common tree and bush types
Intuitive and interactive viewport diagrams to help define biomes and plants
Enhanced climate-based vegetation growth with dual-layer collision resolution
Faster biome region processing from images, curves and height fields
Artist-friendly biome workflows with improved visualization and speed
Biome toolset integration with Solaris for Karma rendering
Biome setup recipe for easy quickstart

ZibraVDB integration for VDB compression, decompression, and game export

2D shape generator with intuitive viewport handles
Hexagon grid generator for game dev
Curve and vector attribute visualization
Updated third-party integrations: AliceVision, RizomUV, Exoside
Updated point cloud exporter and Unreal plugin designed to work with PCG
Easy round-tripping of splines with labeled data between Houdini and Unreal
Updated Unreal plugin with artist-friendly interface for VAT importing
Computer Vision toolset for labelling and rendering synthetic data for ML training
Perforce integration as an optional install

Vulkan viewport

Production-ready with full OpenGL parity and more
Ray traced ambient occlusion, geometry and area lights with denoising
Fast headlight modes: dome, three-point, physical sky
Instanced USD lights
OpenPBR shader support
Multithreaded viewport update and render
No longer using or requiring far clipping plane on free camera
Preservation of near and far clipping planes on free camera
Automated texture cache resizing when VRAM is needed
Zero-lag viewport mirroring for perfectly synced displays: for example, for animators
Improved rendering performance of SimpleDrawable elements
Native 3D support for Copernicus handles and interactive states
MoltenVK support on macOS

Copernicus

Production-ready for all uses except advanced compositing
Post image filtering and advanced slap-comp exposed in Solaris
Fast ray traced geometry texture baker
Live USD rendering directly into COPs
Real-time capturing and processing of live video
Versatile 3D curve rasterization
VDB volume rasterization and integration along camera rays
Advanced noise types, including Chladni, Phasor, Bubble, Cloud 3D, Crystal
Enhancements to Worley Noise (3D) and Fractal Noise (3D)
Grunge patterns available in future production build
Tiled mosaics and Escher-style pattern generation with hyperbolic functions
Rich set of 2D operations, including Color Correct, Sharpen, Defocus, Wipe, ToneMap
Image deformation nodes, including Lattice, Bend, Corner Pin, Swirl
Layer sampling at quantized position for pixelation effect
2D tiling support
Convolve 3×3 filter for edge detection, blurring, sharpening and more
Curvature computation for edge detection, similar to Derivative COP
Powerful and versatile shape scattering/stamping on curves and grids
Heat distortion and lens distortion nodes
Ability to generate mask from curves
Curve 3D node that operates both in 2D and 3D spaceConversion of depth layers to and from depth, distance and height space
Vector Transform 2D node to treat a layer’s UV values as XY location in space
Triplanar UV node to generate UV coordinates for XYZ projections
Triplanar hex-tiling to produce seamless textures over large image areas
Dedicated nodes to convert VDB volumes to image layers and back
Support for VDB inputs and outputs of float, integer and vector type
Position sampling to easily extract VDB slices or create image projections
Fetch node to bring the outputs of a remote COP into the current network
Powerful invoke capabilities via Invoke Geometry and SOP Invoke (Graph)
Ability to run Python snippet on layers and geometry
Geometry spreadsheet support
Improved heightfield importing
Enhanced visualization of height layers
Shadow approximation based on any given height field
COP nodes as camera sources in SOPs
Support for the ‘3D Output’ flag on all nodes
Convenient ‘Default Settings’ window for COP-related settings
Ability to braid multiple layers into one ‘cable’ for more efficient wiring
Full support for interactive handles and states in both COPs and SOPs
Ability to bind 2D and 3D handles to COP nodes
Improved performance for EXR files and faster OCIO conversion
Optimized OpenCL attribute transfers in compiled COP networks
Faster interoperability with Texture Mask Paint SOP
Procedural in-memory image caching for faster playback
Fixed point storage for layers that do not require higher precision
More comprehensive handling of UDIMs
Feedback looping simulation support via Block End COP
Live Simulation option for fast and unconstrained editing of sim behaviour
Reaction-Diffusion solver for biology and chemistry-inspired patterns
Native 2D ‘Flow’ solver for real-time fluid simulations
New 3D sparse Pyro solver for real-time fire and smoke, native to Copernicus and accessible elsewhere in Houdini

Sneak peek: Houdini 21

All of the new features listed in the Houdini 21 sneak peek

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