Mie Loop If Is First 🐑

A branch node built for one very common loop pattern: on the first iteration, use one value; on every later iteration, use another. MieLoopIfIsFirst checks whether the loop is on its opening pass and passes through either then_value or else_value accordingly.

Part of ComfyUI-MieNodes (ComfyUI_MieNodes), MieMieeeee's utility pack, under the 🐑 Loop submenu.

Why you'd reach for it

The killer use is a feedback loop, where each pass takes the previous pass's output as its input. The problem: on the very first iteration there is no previous output yet. So you branch - first pass grabs a seed image (or an empty latent, or a starting prompt), and every pass after that grabs the carried-forward result. That "seed once, then chain" shape is exactly what this node encodes, in one node instead of a tangle of comparisons.

It's the same idea as reading the index and testing == 0 yourself, but cleaner and self-documenting. If your condition is genuinely "is this pass number zero," this reads better than wiring up MieLoopGetIndex and a comparator.

The inputs and outputs that matter

• loop_ctx (MIE_LOOP_CTX) - the loop context; this is how the node knows the current position.
• then_value (any type, optional) - what to output on the first iteration.
• else_value (any type, optional) - what to output on every other iteration.

Outputs:

• loop_ctx - passed straight through, so you can keep the loop chain going.
• value (any type) - then_value on the first pass, else_value otherwise.

Both value inputs are the wildcard * type, so this works for images, latents, strings, numbers - whatever you're switching between. Just keep both branches the same type as what's downstream.

Installing it

ComfyUI Manager → search ComfyUI-MieNodes → install → restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/MieMieeeee/ComfyUI-MieNodes

then restart. No model downloads or heavy dependencies. Under 🐑 MieNodes → 🐑 Loop.

Common issues

Both branches evaluate anyway. ComfyUI generally computes upstream nodes regardless of which branch is selected - the node picks the output, it doesn't prune the graph. If the unused branch is expensive, that cost may still be paid. Structure heavy work so it isn't dangling off a branch you're not using.

Type mismatch downstream. then_value and else_value are wildcards, so nothing stops you from feeding an image into one and a string into the other. The node won't complain, but whatever consumes value will. Keep both branches the same type.

I want the last pass, or an arbitrary index. Use MieLoopIfIsLast for the final iteration, or MieLoopIfCurrentIdx for any comparison like >= 3.