Curl Noise
Fractal noise displaced along the curl of its own field, producing swirling, fluid-like grayscale patterns.
The Curl Noise node computes the curl of an FBM noise field and re-samples the noise displaced along that curl. The result swirls like fluid rather than mottling like plain fractal noise.
- One texture output; two optional texture inputs (domain warp and composite)
- FBM controls (Octaves, Persistence, Lacunarity, Base Noise) plus Curl Strength and Flow Speed
- Found in nerdGRAPH under Generators in the add-node menu
The image on the right is the example patch itself — drag and drop it onto the app (or load it with File → Load) to open the full graph.
Inputs and outputs
| Port | Type | Purpose |
|---|---|---|
| Input | Texture | Domain warp — red/green channels displace the sample coordinates on top of the curl displacement |
| Composite Input | Texture | Composited over the output using the node's Blend Mode and Opacity |
| Output | Texture | The grayscale swirl field |
The warp strength scales with Scale.
Parameters
Opacity, Blend Mode, ALPHA, Threshold Min / Threshold Max — the standard operator header; see Perlin Noise for details.
Structure
- Octaves (1–6, default 4) — detail layers in the underlying FBM field.
- Persistence (0–1, default 0.5) — amplitude decay per octave; higher keeps fine detail louder.
- Lacunarity (1–4, default 2) — frequency step between octaves.
- Curl Strength (0–5, default 1) — how far samples are pushed along the curl field. 0 reduces the node to plain FBM; high values fold the field into tight vortices. It also scales the output level, so very low values darken the frame.
- Base Noise — Perlin or Simplex as the underlying noise for the FBM field.
Transform
- Seed (0–99999), Scale (0.01–10, default 1), Scale X / Scale Y (0.01–50, default 5), Offset X / Offset Y (−20 to 20), Rotation (0–360) — the shared generator transform block.
Dynamics
- Flow Speed (0–5, default 0) — a constant vertical drift through the field, on top of the always-on evolution.
Every slider has a per-parameter animation bar, so any of these can be animated, audio-driven, or MIDI-mapped — see Parameters and Controls.
Examples
Ink in water — Curl Strength 3, Octaves 5, Scale 0.5: large slow vortices with fine internal detail.
Heat shimmer source — Curl Strength 1.5, Scale X/Y around 10, wired into another generator's Input as a domain-warp driver.
Troubleshooting
Output went dark after lowering Curl Strength — Curl Strength also multiplies the output level. Compensate with Threshold Max, or keep Curl Strength above ~0.5.
Swirls are too subtle — raise Curl Strength, and lower Scale so the vortices are large enough to read.