HY-Motion Preview

The cheapest way to find out if the motion you just generated is garbage. HY-Motion Preview takes the motion_data blob from Generate and renders it as a flat 2D stick-figure sequence - no 3D viewer, no export step, just frames you can look at in the ComfyUI preview panel before you invest in an FBX or GLB export. If you're iterating on prompts, this is the node you'll live in. It's also, frankly, the node whose output everyone describes as "odd" - a floating skeleton silhouette on a grey background. That's a feature, not a bug: it's the fastest possible signal that your motion is coherent, which is all you need at iteration time.

The mechanism is pure CPU drawing. It takes the 3D keypoints from the generated sample, projects them onto a flat image, and draws the 21 bones of the upper skeleton with per-limb colors - head and spine one color, arms another, legs another. No rendering engine involved. The output is a proper ComfyUI IMAGE tensor (a batch of frames), so you can wire it into a regular preview/save node, or just let it display.

Inputs

• sample_index - which of your generated samples to draw (0-3). Matters only if you set num_samples above 1 on Generate; each sample is one index.
• frame_step - draw every Nth frame, default 5. Since Generate outputs at 30fps, that's roughly one skeleton every sixth of a second. Lower it for finer detail, raise it to make the preview lighter.
• image_size - 256 to 1024, default 512. Bigger is crisper to read, but each frame is a full image, so there's a real memory cost on long motions.

That's the whole input list, which is the node's quiet strength: three knobs, one output, nothing to break.

The one thing to remember

The preview shows the skeleton of the generated motion - but if you plan to retarget onto a Mixamo character, what you're seeing is the SMPL-style skeleton, not the final character's pose. A motion that looks good as a stick figure can land wrong on a custom rig because of bone mapping differences, and a motion that looks bad in 2D stick form will almost certainly look bad everywhere. Use this node to reject, not to approve. For the "does it actually look right on a character" check, that's what HY-Motion Preview Animation (3D) is for - the interactive viewer shows the wooden boy mesh deforming, which is one step closer to the real thing.

Install-wise there's nothing special: it's just a node in the pack, so once ComfyUI-HY-Motion1 is installed (Manager search, or clone + pip install -r requirements.txt) and a motion has been generated, it works. It's the node you'll wire up first and think about least, which is exactly what a preview should be.