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Houdini

Unit length = 1m
Unit mass = 1kg

Houdini Help pages


vex functions

Handy Nodes

geo
Assemble
Connectadjacentpieces
Peak
Creep

Shortcuts

Action Shortcut
Toggle render view shift r
Split window alt [
Split window 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

Network editor

Network editor

Action Shortcut
Group nodes shift z
Merge nodes shift click multiple outputs, alt click to merge
Switch between workspaces n
Create duplicate alt-drag
Create referenced duplicate ctrl-shift-alt-drag
Switch input wires around Shift R
Connect nodes with drawn line hold J
Organizing
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

General

Action Shortcut
Switch inputs Shift r
Select s
Scale e
Rotate r
Translate t
Handles Tool enter
View mode spacebar
Snaping 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 1
Front spacebar 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 ctrl click on geometry
Zoom in/out alt right mouseclick
Graph editor v
Network Box shift o
Change node shape z
Home g
Display options d (In viewport)
Transformation mode m
Render selection view Shift drag
Place key Alt click
Remove key Ctrl click
Open external VEX editor Alt e
Split viewport space b
Grow selection Shift g
Shrink selection Shift s

Abbreviations

A dotted line means that it's referencing a certain node (so for example, no extra particles will be added(check with the middle mouse))

Object = Object type nodes in an Object type folder. These Object nodes allow you to build transform constraint hierarchies. Geometry type Object nodes contain SOP nodes that construct and modify geometry that inherits any transforms at the object level.

SOPs = Surface OPerators or geometry nodes that are inside an object folder. These are used to construct and modify geometry. Any kind of geometry from polygons to volumes.

DOPs = Dynamic OPerators or simulation/solver nodes that are used to construct simulations. Simulations read in geometry from SOPs and pass this data into the DOP solvers.

SHOP = SHading Operators are materials that represent a shader to apply to geometry. Some are hard-coded with vex and others are folders that you can dive in to and modify the VOPs inside.

VOPs = Vector OPerators inside VOP network nodes are used for everything from building shaders to modifying geometry, volumes, pixels, and more.

VEX = Vector Expression Language. The code language used to write shaders. VOPs are wrappers around VEX code snippets.

CVEX = Context agnostic Vector Expression Language. This has replaced all the VEX specific contexts throughout Houdini. It is a generalized language that uses the same environment and functions anywhere inside Houdini.

COPs = Composite OPerators in composite type folders. Used in image compositing operations.

ROPs = Render OPerators in side ROP Output directories that are used to create render output dependency graphs for automating output of any type of data and for triggering external processes like rendering. Commonly used to generate sequences of geometry, simulation data and trigger Render tasks that generate sequences of images to disk.

CHOPs = CHannel OPerators used to create and modify any type of raw channel data from motion to audio and everything in between. Most users safely ignore the CHOP context, and so can you, for now. Put it on the “get to it later” list when learning Houdini. But definitely keep it on the list.

Add-on's

Name Description
Supercharged R7 GUI & Workflow Enhancements
MLOPs Machine Learning Plugin for Houdini
GSOPs Gaussian splatting in Houdini

HDAs/OTLs

Operator Type Library (or Houdini Digital Asset library)

Link 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 HDA's with thumbnails & copy external files
Material builder

Manual changes

General

First, download ImageMagick
In C:\Users\flori\Documents\houdini20.0\houdini.env file, add

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"

Python

Houdini shelf tool for fast theme switch TextToMtlX

Expression functions

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

VEX

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 LOP's
In Primitive, select “All Geometry Primitives”
Also tick on “Run on Elements of Array Attributes”

@widths = ch("pscale_mult");

Premium

Houdini School
Theory accelerated
Particles
Rohan Dalvi

Vex

VEX-snippets
JoyOfVex
VEX for artists

General

CG Wiki
Houdini Resources
The Vault Manual
Applied Houdini
HoudiniSimon
Nick Taylor
Houdini Blueprints
Convert hipnc to hip files
Getting Started With Houdini
Nitzan Tregerman
Jake Rice Blog
TOPs
Blooming flowers
Simulate Paint Smearing
Unwrapping
Pixelfondue
Konstantin Magnus
Andreas Kjær-Jensen
Creating an CGI Crystal

FX

Creating Lightning with VEX

Terrain

Labs project Dryad Biomes Terrain Handbook Procedural Rocks Integrating a Road into a Heightfield Project Pegasus Procedural racetrack tool

Volumes

Intro to Houdini Volumes, Clouds, and Volume VOPs

Rigging

Spiral skinning
Rig fur dude with KineFX
Apex rig
Generating folder structures
Process Multiple Objects with TOPS
2D animation
Animating Characters

Programming

How not to suck at Python

DemoScenes/HDA's

richlord
superphotoreal.gumroad
Examples of Neural Networks built with VEX

CHOPs/Touchdesigner

What I Found

SOPs

SOP Quicktips

COPs

COP Quicktips
Crystal Fluorite in Houdini 20.5
How to Create Organic Textures

TOPs

Product Proceduralization
TOPs Masterclass

LOPs

Solar Eclipse
MultiShot Workflows
Intro to Solaris

UI

John Kunz UI Customizations for Houdini 19

Pipeline

Files in the packages folder

Preferences

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

Imagemagick

First, download ImageMagick
In C:\Users\flori\Documents\houdini20.0\houdini.env file, add

{
    "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"
        },
    ]
}            

Houdini.env $HOME Houdini Environment Setup Houdini Setup HSITE

Assets

Megascans Karma USD