Mesh Flip Quad Tessellation

This is a subtle one, and it's worth understanding why it exists before you use it: every quad face in a mesh gets triangulated internally along one of its two diagonals, but for a perfectly flat quad it doesn't matter which - the result looks identical either way. On a quad that isn't perfectly flat (slightly bent, twisted, or non-planar, which is common on generated or deformed geometry), the two diagonals produce visibly different shapes once triangulated. This node flips which diagonal gets used, without moving a single vertex.

How it works

It wraps Blender's mesh.flip_quad_tessellation operator. Because it only changes the internal triangulation choice - not the quad's four corner positions - you often won't see any difference at all while editing in Blender itself; quads render fine regardless of their internal split in most viewport shading modes. Where it actually shows up is downstream: when the mesh gets triangulated for real, typically at export to GLB/GLTF or when it lands in a game engine, and a non-planar quad that split "the wrong way" suddenly reads as visibly kinked or bent where the surrounding surface should look smooth.

The inputs and outputs that matter

• BPY_OBJ (optional) - the mesh, with the quad faces you want re-tessellated already selected.

No other parameters - it's a toggle applied to whatever's selected, run it again to flip back.

Output is a single BPY_OBJ.

How to install it

ComfyUI Manager: search "Avatar Graph" and install. Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/avatechai/avatar-graph-comfyui

then pip install -r requirements.txt and restart. Needs Blender's bpy module, pinned to Python 3.10.x - a dedicated conda environment on macOS/Linux, or Avatech's prebuilt Python-3.10 ComfyUI zip on Windows with the pack installed through Manager afterward.

Common issues & troubleshooting

A quad looks fine in Blender but exports with a visible kink or bent-looking shading. This is exactly the scenario this node exists for - a non-planar quad triangulated along the "wrong" diagonal. Select the offending face and run it through this node; if the split was the cause, flipping it resolves the artifact without touching geometry.

Running it produces no visible change at all. That's expected if the quad in question is actually flat/planar - both diagonals of a perfectly flat quad tessellate to the same visual result, so there's nothing for this node to fix on that face. The problem, if there still is one, lies elsewhere (shading flags, normals) rather than tessellation direction.

You're not sure which faces need this. Since the problem is invisible in Blender's own viewport, the practical workflow is to export first, spot the kinked faces in the destination viewer or engine, and come back to flip only those - rather than trying to guess proactively across the whole mesh.