Object Metaball Add

Metaballs are Blender's organic geometry: blob-like objects that automatically merge into one smooth continuous surface as they get close to each other. Object_MetaballAdd wraps bpy.ops.object.metaball_add(), so it drops a new metaball object into your Avatar Graph scene with full control over its shape, size, and transform.

Is this a core avatar node? No. The main pipeline - segment image → mesh layer → aspect ratio → shape keys → Shape Flow - has no metaballs in it. But the pack generates a node for every Blender object-add operator, and metaballs made the cut. Where they're genuinely nice: quick soft geometry for the base of a character. A head, a body, a tail as a cluster of metaballs gives you a smooth cartoon blob in seconds, which you can then convert to a real mesh and run through the same shape-key rigging as everything else. For a stylized "goo" or liquid character, it's the fastest route in the pack.

The mechanism. The node calls the add operator with your settings, then returns the newly created object as BPY_OBJ - unlike the pass-through nodes, this one outputs what it made, so the next node in the chain is already pointed at your fresh metaball. (The generated wrapper returns the active object, and after an add op, that's the new element.)

Inputs that matter:

• type - BALL, CAPSULE, PLANE, ELLIPSOID, or CUBE. Ball and capsule cover most character uses.
• radius - the blob's base radius, default 2.0. This is also what drives the merge distance between adjacent metaballs.
• enter_editmode - if true, you land in edit mode on the new object (mostly irrelevant in a headless ComfyUI run).
• align - WORLD, VIEW, or CURSOR orientation.
• location, rotation, scale - vector inputs (B_VECTOR3) for placing the metaball in the scene.

Output. BPY_OBJ - the newly added metaball object. Feed it to Object_ModifierAdd or the mesh conversion steps to keep building.

Installing it. Ships in Avatar Graph. ComfyUI Manager → "Avatar Graph", or:

cd ComfyUI/custom_nodes
git clone https://github.com/avatechai/avatar-graph-comfyui
cd avatar-graph-comfyui
python -m pip install -r requirements.txt

Restart with --enable-cors-header; pack requires Python 3.10.x (bpy==3.6.0).

Troubleshooting. The most common surprise: metaballs only visually merge inside a single metaball family (same parent object), so two separately-added metaballs won't blend into each other until you make them part of the same family. The exported result is a blob surface, not a textured 2D card, so don't expect it to behave like a mesh layer from the segmentation path. If you want it animated later, convert it to a real mesh and add shape keys - which is exactly the kind of plumbing the rest of this pack is built for.