Blender Input Seed

When you're rendering a shot from Blender and the result isn't right, half your workflow is re-running with a different seed until something lands. BlenderInputSeed puts that dial on the add-on's panel so you can scrub seeds without leaving the viewport - and more importantly, so you can lock one while you iterate on everything else. It's the node that makes iteration in the Blender pipeline feel like iteration instead of a fetch quest back to ComfyUI.

It's a subclass of ComfyUI's built-in Int primitive, with the seed-specific scaffolding the add-on needs. In a ComfyUI-only graph it outputs its value; the other inputs define the spinner the Blender add-on renders. One notable detail: the pack strips the standard "control after generate" behavior from this node - no randomize-on-each-run, because in Blender you want the seed to be stable while you're iterating and only change when you say so. That's the right call for this use case and worth knowing before you're confused why the seed never advances on its own.

Inputs and outputs

• value - the seed the node outputs. This is what the KSampler actually sees.
• default - the seed it starts at when the workflow loads. Set this to a fixed value if you want a reproducible starting point for a shot.
• min / max - bounds on the spinner. The default min is 0, which is fine for seeds - negative seeds are unusual in this workflow anyway.
• step - how much the spinner moves per click. 1 is plenty; you're not sweeping this field in big jumps.
• order - panel position, lower first.

There's an optional group input for nesting inside a Blender Input Group box. Output is a single INT that wires into your KSampler's seed socket.

Installing it

Whole-pack routine. ComfyUI side: ComfyUI Manager → search "ComfyUI-Blender", or:

cd ComfyUI/custom_nodes
git clone https://github.com/alexisrolland/ComfyUI-Blender

Restart ComfyUI. No extra Python dependencies, but you need a current ComfyUI - the nodes are schema v3 and the README says older versions won't load them. The Blender add-on is a separate ZIP from the latest release, installed via Edit > Preferences > Add-ons > Install from Disk.

Where people get burned

The usual trap is expecting the seed to randomize between runs. It won't - by design, as above. If you want variety, set the value yourself between takes, or put a native randomize node upstream and let this one be a fixed override. Second gotcha, shared by the whole pack: the panel only builds after you export the workflow in API format and import it into the add-on, and the node title becomes the label. Third: if you're running Blender and ComfyUI on one GPU, VRAM is shared - scrubbing a seed is cheap, but each new seed is a new generation, and the viewport is already eating memory. Iterate smart: lock the seed, change the thing that was actually wrong.