Animated Shape Mask

Animating a mask is one of those things that sounds easy until you try it - you need a moving region that changes every frame, and drawing 64 of them by hand is miserable. Animated Shape Mask is the cheat code: it generates a whole mask animation procedurally from a handful of parameters. Moving bands, traveling sine waves, expanding or contracting circles - pick a mode, pick a resolution, and out comes an image sequence where each frame is a mask you can drive an inpainting reveal with.

This is the sibling of Animation_RGB_Mask in the Eden pack, and the family resemblance shows: one generates color-coded region animations, this one generates grayscale shape masks. If your goal is a clean binary or shaded mask sweep - like a cinematic reveal where content is masked in as a band moves across - this is the node.

How it works

Under the hood it's a MaskAnimationGenerator that renders each frame's mask at your chosen width/height, then stacks the frames into an IMAGE batch. The modes break into three families:

• moving_band_ - a solid band sweeping across the frame (top-down, bottom-up, left-right, right-left).
• sine_wave_ - a wavy band, with wave_frequency controlling ripple and wave_amplitude_ratio controlling wobble, sweeping across in one of four directions.
• expanding_circle / contracting_circle - a circle growing from or shrinking to the center.

Two knobs matter more than the rest. num_shades (default 2) sets how many grayscale levels the mask uses - 2 gives hard black/white, which is what you want for feeding a real inpainting mask. Crank it to 16–64 and you get smooth gradient shades instead, which looks great composited but behaves differently when a KSampler treats it as a mask. invert_mask flips which side is active, useful when you want content to leave instead of arrive.

There's also a gradient_type (none / all_edges / trailing_edge) plus gradient_width_ratio that softens mask edges with a distance-based falloff (via OpenCV's distance transform) - all_edges fades every boundary, trailing_edge fades only the moving edge, which gives a lovely blur-sweep reveal effect.

The outputs

• IMAGE - the mask animation, total_frames frames of width×height.
• num_shades, width, height - echoed back as INTs so downstream nodes can use them without guessing.

Wire the IMAGE into a mask-conversion node and then into Set Latent Noise Mask on an inpaint KSampler, and you've got a frame-consistent animated reveal. The KB's inpainting essay is worth a re-read here: masked inpainting still owns bit-identical unmasked pixels, which is exactly the property an animated reveal needs - the already-revealed area stays frozen while only the newly exposed band regenerates.

Installing

It's part of edenartlab/eden_comfy_pipelines (Eden.art nodesuite):

cd ComfyUI/custom_nodes
git clone https://github.com/edenartlab/eden_comfy_pipelines.git
cd eden_comfy_pipelines
pip install -r requirements.txt

Or ComfyUI Manager → search "Eden". It needs opencv-python (in the pack's requirements) for the gradient falloff, but nothing else exotic.

Gotchas

Two real ones. First, the binary-mask trap: the pack prints a warning if you set gradient_type to anything but none while num_shades is 2 - gradients need multiple shades to exist, so you'll get a hard mask and wonder why your soft fade didn't happen. Second, remember the output is IMAGE, not MASK - most inpainting nodes want a MASK, so throw it through a converter (or use it as IMAGE conditioning) before it hits a KSampler. And don't forget the obvious: a total_frames of 64 at 512×512 is a chunk of VRAM when it's stacked as a single batch, so keep resolutions sane for long sweeps.