Houdini

Procedural 3D animation and VFX software by SideFX, built around a node-based workflow.

Units1 unit = 1 meter, 1 mass = 1 kg

Tips

TIP

A dotted line in the network editor means it's referencing a certain node (e.g. no extra particles will be added - check with MMB).

Handy Nodes

Node	Description
`geo`	Geometry container
`Assemble`	Create packed primitives from groups or pieces
`Connectadjacentpieces`	Create constraint geometry between adjacent pieces
`Peak`	Translate points along their normals
`Creep`	Deform geometry across a surface

Shortcuts

Action	Shortcut
Toggle render view	`Shift` `R`
Split window	`Alt` `[` / `Alt` `]`
Close window	`Ctrl` `W`
Dashbox	`Ctrl` `D`
Focus	`Ctrl` `Alt` `S`

Viewport

Action	Shortcut
Create	`C`
View mode	`V`
Select everything	`N`
Toggle quad view (orthographic and perspective)	`B`
Selection group	`Enter` then `9`

Network Editor

Network editor shortcuts reference

Action	Shortcut
Group nodes	`Shift` `Z`
Merge nodes	hold `Shift` click multiple outputs, hold `Alt` click to merge
Switch between workspaces	`N`
Create duplicate	hold `Alt` drag
Create referenced duplicate	hold `Ctrl` `Shift` `Alt` drag
Switch input wires around	`Shift` `R`
Connect nodes with drawn line	hold `J`

Organizing

Action	Shortcut
Notepad	`Shift` `P`
Underlay	`Shift` `O`
Line out	`L`
Wiring style	`Shift` `S`
Create re-route	hold `Alt`
Align selected nodes	`Shift` `A`

MPlay

Action	Shortcut
List shots	`Alt` `L`

Task Operators

Action	Shortcut
Cook node	`Shift` `G`
Dirty node	`Shift` `D`
Dirty and Cook node	`Shift` `V`

General

Action	Shortcut
Switch inputs	`Shift` `R`
Select	`S`
Scale	`E`
Rotate	`R`
Translate	`T`
Handles Tool	`Enter`
View mode	`Spacebar`
Snapping pie menu	`X`
Wire only	`Q`
Wire over shaded	`Shift` `W`
Parameters	`P`
Cut wires	`Y`
Enlarge parameter box	`Ctrl` `E`
Color nodes	`C`
Perspective	`Spacebar` then `1`
Front	`Spacebar` then `3`
Sticky note	`Shift` `P`
Network overview	`O`
Go up in node hierarchy	`U`
Clean up the network / layout all	`L`
Full screen	`Ctrl` `B`
Focus on object	hold `Ctrl` click on geometry
Zoom in/out	`Alt` `RMB`
Graph editor	`V`
Network Box	`Shift` `O`
Change node shape	`Z`
Home	`G`
Display options	`D` (in viewport)
Transformation mode	`M`
Render selection view	hold `Shift` drag
Place key	hold `Alt` click
Remove key	hold `Ctrl` click
Open external (word/VEX) editor	`Alt` `E`
Split viewport	`Spacebar` then `B`
Grow selection	`Shift` `G`
Shrink selection	`Shift` `S`
Make font bigger	`Ctrl` `+`
Make font smaller	`Ctrl` `-`

Context Types

Context	Description
Object	Object type nodes in an Object type folder. Build transform constraint hierarchies. Geometry type Object nodes contain SOP nodes.
SOPs	Surface OPerators — geometry nodes inside an object folder. Used to construct and modify geometry (polygons, volumes, etc.).
DOPs	Dynamic OPerators — simulation/solver nodes. Read in geometry from SOPs and pass data into DOP solvers.
SHOP	SHading Operators — materials representing a shader to apply to geometry.
VEX	Vector Expression Language — custom language loosely based on C/C++ and the RenderMan shading language. Not an alternative to scripting, but a smaller, more efficient language for writing shaders and custom nodes.
VOPs	Vector OPerators — wrappers around VEX code snippets. Used for shaders, geometry, volumes, pixels, and more.
CVEX	Context-agnostic Vector Expression Language. Replaced all VEX-specific contexts — generalized language that works anywhere in Houdini.
COPs	Composite OPerators — used in image compositing operations.
ROPs	Render OPerators — create render output dependency graphs for automating output and triggering external processes like rendering.
CHOPs	CHannel OPerators — create and modify raw channel data from motion to audio.

Add-ons

Name	Description
Supercharged R7	GUI & Workflow Enhancements
MLOPs	Machine Learning Plugin for Houdini
GSOPs	Gaussian splatting in Houdini
Modeler	Fast and intuitive polygonal and subdivision mesh editing
SDFM	Free, open source SDF Modeling Toolset

HDAs / OTLs

Operator Type Library (or Houdini Digital Asset library)

Name	Description
qLib	A collection of tools
BoomBox	Fracturing and art directing RBD sims
Wrinkle Deformer	OpenCL wrinkle deformer
Auto Rig Lite	Auto Rigger
BoxCutter	BoxCutter Demo Houdini
DASH	Quality of Life utilities package
IPOPs	Geometry AOVs for Karma CPU & XPU
Asset Handler	Generate HDAs with thumbnails & copy external files
Material Builder	Karma MatX Builder

Expression Functions

centroid(surface_node, type)detail(surface_node, attrib_name, attrib_index)

VEX Snippets

Remove Points by ID:

if (rand(@id*ch('seed'))>chf('ratio'))
{
    removepoint(0,@ptnum);
}

Create vector based on relative location from point 2nd input:

vector a = point(0, "P", @ptnum);
vector b = point(1, "P", 0);
@v = (a-b);
@v *= chf("mult");

Point normals outward:

vector a = set(0,0,0);
@N = normalize(a + @P);

Change particle size in LOPs — in Primitive, select "All Geometry Primitives" and tick "Run on Elements of Array Attributes":

@widths = ch("pscale_mult");

Pipeline

Houdini Companion - HtoolsQS

Files in the packages folder.

Preferences

json

{
    "env": [
        { "HOUDINI_USER_PREF_DIR": "P:/Houdini__HVER__" },
        { "HSITE": "P:/Houdini" },
        { "HOUDINI_DESK_PATH": "P:/Houdini/desktop" }
    ]
}

ImageMagick

First, download ImageMagick. Then add to your packages:

json

{
    "env": [
        { "PDG_IMAGEMAGIC": "C:\\Program Files\\ImageMagick-7.1.1-Q16-HDRI\\magick.exe" },
        { "PDG_FFMPEG": "C:\\Program Files\\ImageMagick-7.1.1-Q16-HDRI\\ffmpeg.exe" }
    ]
}

Pipeline references:

Houdini.env $HOME Houdini Environment Setup Houdini Setup HSITE

Assets

Megascans Karma USD

Python

Houdini shelf tool for fast theme switch TextToMtlX

Resources

Houdini

Tips ​

Handy Nodes ​

Shortcuts ​

Navigation ​

Viewport ​

Network Editor ​

MPlay ​

Task Operators ​

General ​

Context Types ​

Add-ons ​

HDAs / OTLs ​

Expression Functions ​

VEX Snippets ​

Pipeline ​

Preferences ​

ImageMagick ​

Assets ​

Python ​

Resources ​

Learning Platforms & Courses

General

VEX

Tutorials

Tools & Pipeline

Tips

Handy Nodes

Shortcuts

Navigation

Viewport

Network Editor

MPlay

Task Operators

General

Context Types

Add-ons

HDAs / OTLs

Expression Functions

VEX Snippets

Pipeline

Preferences

ImageMagick

Assets

Python

Resources