Logic node

Derfuu's take on an if statement. It compares two values with an operator you pick and, based on true/false, passes through one of two other values. "If A is greater than B, output this, else output that." In a graph that otherwise just runs straight down, this is how you get a branch.

It's a "Functions" node in Derfuu_ComfyUI_ModdedNodes. Quick naming note: "Logic node" (with a space) is the older class name; current pack builds register it as DF_Logic_node. Same node, newer page here - the main visible difference is the operator labels (this older version uses bare >, <, =, AND, OR, XOR).

How it works

• Operation - >, <, =, AND, OR, XOR. First three compare, last three are boolean logic.
• CompareValue_A (required, wildcard *) and CompareValue_B (optional, *) - the values being compared. The * type accepts anything.
• OnTrue / OnFalse (both optional, *) - the values passed out for each result.
• Output: a single wildcard *.

Behavior, per the pack README: it "compares 2 values and returns one of 2 others (if not set - returns False)." Wire OnTrue/OnFalse and it emits one of them; leave them blank and it emits the raw boolean of the comparison.

Where you'd use it

Reacting to inputs. Compare a computed number against a threshold, or an image's width against its height (via Get image size), and use OnTrue/OnFalse to pick which value drives the downstream graph. It turns a fixed pipeline into one that adapts to what it's fed.

Keep expectations right: it selects a value, it doesn't skip execution of a branch. For actually muting or bypassing whole sections of a graph, that's rgthree's group bypassers or Impact Pack switches. This is the "pick a value" primitive.

Common issues & troubleshooting

This node is red in an old workflow - or vanished after a pack update. That's the core Derfuu gotcha. The maintainer has a documented habit of deleting deprecated node classes on reorganizations rather than leaving them in labeled as old, so saved graphs break. Replace the red node with the current DF_Logic_node and re-wire.

ModuleNotFoundError: No module named 'custom_nodes.Derfuu_ComfyUI_ModdedNodes'. Same cause - an old graph pointing at a module path that moved. Update the pack, reload, swap the node.

It returned False instead of my value. OnTrue/OnFalse weren't wired. Connect them to output real values instead of the bare comparison result.

Mismatched compare types. The * ports take anything, but comparing a string to a number is meaningless - keep both compare values the same kind.

Install: ComfyUI Manager → search "Derfuu" → install → restart, or cd ComfyUI/custom_nodes && git clone https://github.com/Derfuu/Derfuu_ComfyUI_ModdedNodes then restart. No models, no heavy dependencies.