array1 is null

array1 is null is the smallest node in this 3D pack, and it's the one you forget exists until a batch comes back empty and you spend an hour wondering why. It answers one question - is this list empty? - as a clean boolean you can feed into a switch or conditional. It's a guard node, and guards are how you stop an empty array from silently producing garbage downstream.

The single input is array_input (a LIST). The single output is IsNull (a BOOL), which is true if the list is empty - or, usefully, if it's not a list at all. That second case matters more than it sounds: if a node upstream fails and hands this an None or a non-list value, IsNull comes back true, which is exactly the signal you want your guard to react to. A node that treats "empty" and "broken" as the same condition is the right kind of paranoid for a batch pipeline.

The logic is dead simple under the hood: return true if the input isn't a list, or if it's []. Any real list, even one with junk in it, returns false.

Where you'll actually use it: wire it into a conditional or switch that skips a processing branch when there's nothing to process, or use it to fail loudly - feed the boolean to a node that shows a message when a batch is unexpectedly empty. Combined with the pack's generators, it's also a nice sanity check: generate a camera sweep with array1 end increment, run it through is null, and you'll instantly know if your parameters collapsed to an empty list (which, as the generator docs hint, can happen at certain edge inputs).

Honest take: this is a genuinely thin utility - one boolean in, one boolean out - and you might never need it. But for batch-heavy 3D workflows, the "did that generator actually produce anything" check is worth the one node. There's nothing to configure, nothing to get wrong.

This ships in 807502278/ComfyUI-3D-MeshTool, a one-developer 3D utility pack. Pure Python, no models. Install via ComfyUI Manager (search "ComfyUI-3D-MeshTool") and restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/807502278/ComfyUI-3D-MeshTool
cd ComfyUI-3D-MeshTool
pip install -r requirements.txt

And the pack's standing quirk: the author renames nodes between releases, and old instances turn red in saved workflows - recreate the node and reconnect. When your batch mysteriously produced nothing, a true out of this node is your first clue.