Houdini to TouchDesigner

Last updated Jul 20, 2023 Edit Source

• Touchdesigner

TouchDesigner was born as a fork of Houdini 4.1, which shows in some methodologies and naming conventions. From a Nuke compositing standpoint there are many similarities when it comes to 2D image manipulation as well.

Disclaimer:

The following are mostly the notes I took when starting to learn TD. Don’t read this if you want to get started. I instead recommend to check out Bileam Tschepe’s Beginner Course. This might only be useful if you are looking for some Houdini analogies!

• Tab to create nodes
• P toggles the parameter window on top of the network graph
• C toggles color options for nodes
• O toggles a small map of all the nodes
• D toggles displays the currently selected node in the background
• U exits node/group and goes one layer up
• I enters/opens selected node/group (one layer down)
• MiddleMouse Click on a node output lets you connect it to a new node directly similar to clicking the output of a Houdini node before searching and adding something
• Right Click on connections lets you insert or add operators. The latter only connects the input and not the output of the new node
• A activate selected viewer
• H center viewport
• W wireframe mode in SOP viewport
• N toggle big names in network graph
• MiddleMouse Click on nodes/operators gives you all the information like in Houdini
• Mouse Click on the outer edge of an operator resizes the viewport to fit the aspect ratio
• P in SOPs viewer active mode opens display options

When working you are in “Designer” mode. This is where you see your network and the TD UI. Perform mode is a setting that hides all the UI and only Displays the output of your network in a new window. You can activate “Perform” mode by pressing F1 and exit it by hitting ESC. Closing the window with the windows/macOS buttons closes TD fully.

For fullscreen output you have to use a Window Comp which has a setting Open that has to be set to 1 and a drop down menu that allows you to select borderless.

COMPs (Object Components, Panel Components) - and other miscellaneous components. Components contain other operators:

• Panels to build UIs with buttons and what not
• Containers
• Dynamics solvers
• Import Export Nodes (FBX, USD, .. )

TOPs (Texture Operators) - all 2D image operation:

• 2D image manipulation like in COPs or normal Nuke

CHOPs (Channel Operators) - motion, audio, animation, control signals:

• very much like Houdini CHOPs
• manipulating values and driving parameters with them
• anything that’s got to do with audio
• input for different sensor types or controllers (e.g. midi)

SOPs (Surface Operators) - 3D points, polygons and other 3D “primitives”:

• equal to SOPs in Houdini
• working with geometry

MATs (Material Operators) - materials and shaders:

• like MAT and SHOP nets in Houdini

DATs (Data Operators) - ASCII text as plain text, scripts, XML, or organized in tables of cells:

• doesn’t really exist in Houdini as data is usually stored in attributes

Custom (Custom Operators):

• you can create custom Operators which can belong to any type with C++

You can’t connect operators of different types together but there are many ways to convert between types or reference outputs into parameters just like in Houdini.

• Star: Viewer Active
• Arrow: Bypass
• Lock: Unlock/Lock
• Target Circle: Display
• Dot: Activate BG Display

• Subnet > Base
• Poly Frame > Attribute Create (only generates normals and tangents)
• Merge = Merge
• Transform = Transform
• Sort = Sort
• circle, grid, etc. are mostly the same

• Grade, Color Correction, Invert > Levels
• Saturation, Hueshift etc. > HSV Adjust
• Merge > Composite
• Reformat > Resolution
• Shuffle > Channel Mix (similar to old shuffle style)
• Crop = Crop
• Blur = Blur
• Transform = Transform

Under the Help tab you can find Operator Snippets where you can load examples for most of the nodes

• always use null nodes to mark the end/output of something (especially useful when the output is referenced somewhere)
• ‘Copy Parameter’ / ‘Paste Reference’ Workflow is the same
• You can Lock, Bypass, and Display nodes

• in TD the axis of any image (TOPs) are mapped to uv coordinates ranging from 0-1 (think STMap in Nuke)

sources / further reading:

• TouchDesigner Glossary - Derivative
• Operator - Touchdesigner DOCs - Derivative
• TouchDesigner Beginner Course - bileam tschepe (elekktronaut)
• Why To Use NULLs – TouchDesigner Tips, Tricks and FAQs 2 - bileam tschepe (elekktronaut)