ModelSamplingSD3 (Ray)

This is the minimal member of the Ray sampling-patch family: one knob, one job. RayModelSamplingSD3 applies the SD3-style flow sampling patch to the model on your Raylight workers, and the only thing you actually set is shift. Default is 3.0.

If you've used SD3, Flux, or Chroma (the SD3-based model the KB tracks closely), you already know the drill: these are rectified-flow models with a near-straight noise-to-image trajectory, and shift decides whether sampling effort piles onto the composition-heavy early steps or spreads out. It's the modern, flow-matching replacement for "picking a scheduler." SD3's reference value is 3; the KB's guidance is to treat the model card as ground truth and not chase it around.

There is exactly one input that matters here, and that's it. Unlike the Flux variant there's no width/height pair - this is the plain discrete-flow shift patch with a CONST sampling type. It takes ray_actors in, applies model.clone() + the shift patch on every worker via @ray_patch, and returns the same ray_actors stream so you can keep chaining patches.

Where you'd actually use it

Any SD3 / Stable Diffusion 3 / Chroma-family generation running through Raylight. In the pack's supported-models table, Chroma and Chroma Radiance are the SD3-adjacent names you'll see in the wild, and they want their shift set. Chain it after Ray Init Actor and before your Ray KSampler, same as every other sampling patch. On a single GPU, ComfyUI's built-in ModelSamplingSD3 is the same thing without the Ray indirection - this node exists because the model is on the workers.

Install

Standard raylight install:

cd ComfyUI/custom_nodes
git clone https://github.com/komikndr/raylight
cd raylight
pip install -r requirements.txt

Restart ComfyUI, or install "raylight" from ComfyUI Manager.

Gotchas

Keep it boring. shift = 3 is the reference for SD3; if your output looks structurally broken, check resolution and scheduler before you start cranking shift - a scheduler that applies its own sigma shift (a few custom ones do) will silently ignore this node's value and send you chasing a ghost. And the standing Raylight rule applies: no Ray Init Actor upstream, no effect. This is a worker-side patch, not a standalone node.