Houdini

Recommended Readings

Industry / Case Studies

• ​Rohan Dalvi

• Entagma

Documentation / Tutorials

• https://www.sidefx.com/docs/houdini/vex/index.html

• VEX Language Reference

• VEX Functions

• https://www.sidefx.com/learn/getting_started/

• https://www.hipflask.how/

• https://www.sidefx.com/docs/houdini/

• https://www.sidefx.com/forum/

• SideFX Digital Learning Material

• Algorithmic

  • Junchiro Horikawa

Repositories / Wiki

• Deborah Fowler

• Tokeru

  • Joy of VEX

• Tosin Akinwoye

• Kiryha

• Jtomori

• John Kunz

Mathematics

• Khan Academy

• Procedural noise

• 3Blue1Brown​

• Cross Product and Dot Product: Visual explanation

• The Applications of Matrices | What I wish my teachers told me way earlierers told me way earlier

Abstract

• Houdini is a 3D software known for it's procedural generation tools. The word procedural might sound vague to you but in short what it means to to me is that:

  • Non-destructive setup

  • Flexibility and adaptability

  • The software do most of the work; you just need to create the tools

• This software has a steep learning curve, and it is especially difficult if you have not used a node-based software such Nuke previously. It is natural not to comprehend what you are doing where you are starting out; just keep watching tutorials daily and one day your brain will somehow makes sense of the things you never thought you understand. This pretty much applies to learning of any subject matter.

• To get started with Houdini, start by thinking in "points". If you can manipulate points in any way you want; you would have no problem with the software.

Shortcuts

Function	Windows	Mac
View properties		MMB
Reveal Properties Panel		P
Align nodes Layout nodes		Hold A + Drag (Down/Right) L
Move in-out of nodes		U & I
Cut node connection		Y
Radial Menu		V
Network box		shift + O
Camera views		Cmd 1/2/3/4
Delete Channel		Ctrl + Shift + LMB
		Shift W
Save Quickview	Ctrl + numpad 6-9	Cmd + numpad 6-9
Load Quickview	Space+ numpad 6-9
Go to next / previous level	Alt + Left / Right arrow

Terminology

Item	Description
Object	Object type nodes in an Object type folder. These Object nodes allow you build transform constraint hierarchies. Geometry type Object nodes contain SOP nodes that construct and modify geometry that inherit 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 passes this data in to 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 which 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 generates 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.

Best practices / Tips

• When using copytopoint for an object and a grid, you can attach an add node after the grid to delete all unused geometry; leaving only the points.

• With more than one node selected, hold alt/option and drag a new connection. It will automatically create a mergenode.

• When using the TAB menu to create a node, you can type the initials of the node name to access it. Example:

  • Point wrangle: PW

  • Attribute from Map: AFM or AM