Noise Effector

Noise Effector is a direction that changes smoothly through space. Neighbouring points get similar directions and distant ones differ, so a low-strength noise on top of gravity adds the irregularity real trees have without the jitter of a random value per point. See Shaping.

Add it from the effector picker on any node with an effector stack (see Where effectors go), or from the Effectors button on the Natsura toolbar. It has no inputs to wire.

Where the pattern lives

Position decides the space the noise is sampled in. Inherit (the default) uses the space of whatever the effector drives, such as along a strand or across a surface, so the same effector patterns sensibly wherever you use it. Position samples in world space: the pattern stays fixed and growing geometry moves through it. Attribute samples through a point attribute you name, such as rest_P or uv.

Element Size is the size of the features: larger gives smooth, flowing bends, smaller a busier wiggle. Offset slides the pattern, which is how you make two noise effectors in the same space differ.

Which way it pushes

Direction decides how the field acts. Inherit pushes only along the direction the consumer declares, such as a surface normal, with the noise setting how far; where the consumer declares no direction it acts as Free. Free acts in all three dimensions. Attribute pushes along a vector attribute you name in Noise Along Vector, and points where that vector is zero get nothing. Noise Sign keeps both directions, or only the positive or negative side for a one-way push.

Character

Swirl (on by default) makes curl noise, which flows and never bunches up. Off gives a drifting push that can cluster. Sharp folds the noise into ridges. Octaves adds finer layers; with more than one, Lacunarity sets the spacing between layers and Roughness how much the finer ones count. Three octaves with a wide Lacunarity reads as natural wind.

Amplitude sets the strength before the row's own strength. Use the row's strength, or a map on it, for artistic control, and Amplitude to balance this effector against others.

Name, under Advanced, is the attribute this effector writes.

Status

Noise Effector is experimental. Noise Effectors from scenes before 0.7.2 are converted on load to the current noise when their old Scale was anything but 0 or 1. The pattern differs, and Element Size and Amplitude are set to match the old size and strength. One left at Scale 1 is not converted and loads with the current defaults, so check its Position and Direction.