AnimationCHOP

Keyframe animation curves for TouchDesigner, as native C++ Custom Operators with a full Python API.

Build curves from keyframes with cubic Bézier interpolation, drive them from Python, and get them back as CHOP channels — without rebuilding an animation system out of Pattern CHOPs and Lookup CHOPs every time.

The animation maths lives in anim, a standalone C++20 library; these operators are the TouchDesigner binding around it.

What's included

AnimationCHOP	Holds named animation channels and cooks them to CHOP samples. This is the operator you script against.
AnimationViewCHOP	Exposes an AnimationCHOP's internals as CHOP data — samples, keyframes, Bézier segments, channels — for building UI on top.
Keyframer.tox	A ready-made keyframe editor component built on both operators, with a GLSL-rendered curve view.

Features

• Named channels, each an independent curve; multiple channels per operator
• Per-keyframe interpolation: Constant (step), Linear, Bezier
• Bézier handle modes: Flat, Smooth, Aligned, Free, and the aligned variants AlignStrict / AlignFlex / AlignAdjustable
• Per-channel extrapolation before the first and after the last keyframe: Hold, Repeat, Mirror
• Output modes: a fixed time range, an auto range fitted to the content, an index driven by an input CHOP, or a single scrubbed sequence index
• A complete Python API — create and edit channels and keyframes, evaluate the curve at any time, and save or restore whole-animation state as a plain dict
• Animations persist inside the .toe: channels and keyframes are saved with the project and restored on load, with no external files

Requirements

• TouchDesigner 2025.33070 or newer. Earlier builds will refuse to load the operators. That build is where the Custom Operator API gained node data persistence (saveData/loadData), which is how animations are stored in the .toe; the operators target CHOP API version 10 / common API version 2.
• Windows or macOS. Windows builds are x64.

Installation

1. Download the archive for your platform from Releases.

2. Copy the operator libraries into a Plugins folder beside your .toe:

   MyProject/
     MyProject.toe
     Plugins/
       AnimationCHOP.dll        (or .plugin on macOS)
       AnimationViewCHOP.dll
   

   TouchDesigner only loads Custom Operators from a Plugins folder next to the project file, or from the system-wide plugin folder.

3. Open the project. The first load of a new operator build shows a prompt asking you to trust it — approve it once.

4. Add an AnimationCHOP from the operator palette, or drop in the included Keyframer.tox for the full editor.

The release archive also contains an example project you can open directly.

Quick start

Everything is driven from Python on the operator itself:

n = op('animation1')

# Create a channel and key it
tx = n.create_channel('tx')
tx.create_keyframe(0, 0)
tx.create_keyframe(30, 100, n.Function.BEZIER, n.HandleMode.SMOOTH)

# Evaluate anywhere on the curve
print(tx.evaluate(15))

# Edit in place...
tx.set_keyframe_value(1, 250)

# ...or read, modify, write back
kf = tx[0]
kf.function = n.Function.LINEAR
tx[0] = kf

# Save and restore the whole animation
state = n.state
n.clear()
n.state = state

One thing to know before writing much against it: Channel is a live handle, but Keyframe and Point are values. tx[0] gives you a detached copy, so setting a property on it does not reach the channel until you write it back. The docs explain why — it is a consequence of how keyframes have to be re-solved against their neighbours.

Documentation

Full Python API reference under docs/:

• AnimationCHOP — the operator: channels, range, state
• Channel — a single curve
• Keyframe · Point
• Function · HandleMode · RangeEnd

Building from source

git clone --recurse-submodules https://github.com/Actualize-Interactive/AnimationCHOP.git
cd AnimationCHOP

(If you already cloned without submodules: git submodule update --init --recursive.)

# Windows
.\build.ps1

# macOS
./build.sh

Either way the built operators are copied into td/Plugins/ so the example project picks them up.

Windows vendors the CPython 3.11 headers and import libraries it needs, so there is nothing to install. macOS builds against TouchDesigner's own Python framework and expects TouchDesigner in /Applications.

Testing

cmake --workflow --preset dev     # configure, build, run the unit tests

The pytest suite runs the real binding sources against a fake TouchDesigner context, so it needs no TouchDesigner install. There is also an integration harness that drives a real project inside TouchDesigner. See TESTING.md.

Contributing

See CONTRIBUTING.md.

License

MIT — see LICENSE.

The TouchDesigner SDK headers under ext/td/ are Derivative Inc.'s and carry their own terms; the vendored CPython headers are under the PSF License. See NOTICE for the full third-party attribution.