Interpolate Coords

KJNodes files this one under KJNodes/experimental, and that's the honest label - there's no writeup for it beyond "Interpolates coordinates based on a curve," and it doesn't show up in any tutorial or community thread. So let's work from the schema and be straight about what's known versus inferred.

The node takes two things: a coordinates string and an interpolation_curve. coordinates is the little point-list format a handful of KJNodes tools speak - a list of x/y pairs, one per frame or step, the same shape you'd get out of a coordinate-generating node or type by hand. interpolation_curve is a float curve - not a single number but a drawable easing curve widget, the kind you'd use to say "ease in slow, then snap fast" instead of moving at a constant rate. What Interpolate Coords does is resample your point list through that curve: instead of moving between your keyframed coordinates linearly, the path speeds up and slows down according to the shape you drew. The output is the same coordinates string format, just redistributed - so it slots right back into whatever consumed the original list.

Where you'd actually use this: anything that moves a point over a batch of frames - panning a virtual camera across an image, animating where a mask or crop window sits from frame to frame, walking a subject's position through a video generation. A straight linear interpolation between two points looks mechanical; running it through an ease-in-ease-out curve looks like something actually decided to move that way.

The inputs and outputs that matter

There are exactly two inputs and one output, so there's no picking-and-choosing here:

• coordinates - your source path, as a string.
• interpolation_curve - the easing curve to resample along.
• Output: coordinates, resampled.

How to install it

Same as every node in this pack - via ComfyUI Manager, search "KJNodes for ComfyUI" and install, or manually: cd ComfyUI/custom_nodes && git clone https://github.com/kijai/ComfyUI-KJNodes, then pip install -r ComfyUI-KJNodes/requirements.txt (portable installs run that through python_embeded\python.exe -m pip install -r ...), then restart. No extra dependencies or model downloads for this one specifically - it's pure Python coordinate math.

Common issues & troubleshooting

The main way this breaks is a coordinates-format mismatch. There's no schema validation happening in the graph itself - if the string you feed in isn't shaped the way the node expects, or came from a source that uses a slightly different convention, you'll get an error or garbage output rather than a helpful message. If you're building the coordinate string by hand rather than pulling it from another node, double- and triple-check it against a known-good example before you spend time debugging the curve itself.

Worth pairing this with Plot Coordinates (also in this pack) while you're setting it up - it renders your coordinate string to an actual image sequence via Matplotlib, so you can see the path Interpolate Coords produced instead of reading JSON and guessing whether the curve did what you wanted. Given how thin the documentation is here, that visual check is doing a lot of the debugging work a proper spec would otherwise do for you.