Vector fields
A formula that returns an arrow, a direction and a length, at every point in space.
What it is
A vector field answers one question everywhere: which way, and how hard?
Ask it at any point and it returns an arrow. The direction is where to go, the length is how strongly. Wind blowing left to right, water swirling down a drain, heat rising off a surface: all vector fields.
Like every Fields, it is a formula rather than stored data. Nothing is baked into a grid until something asks, so there is no fixed resolution and no memory cost. Sample it at a million points or one and it is the same field.
A vector field is the close cousin of a Scalar fields (one number per point) and a Colour fields (a colour per point). Same idea, different payload.
An arrow needs three numbers, an x, y and z amount, so a vector field lives in 3D. In a flat 2D scene the third amount stays at zero.
When to use one
Use a vector field to push, flow, or steer something.
Drive a simulation. Wind, currents, turbulence, attractors and vortices are all vector fields. In simulation they appear as forces. See Force Field and Forces & collisions.
Carry particles along. Each particle reads the arrow under it and drifts that way. Curl noise gives smoke-like swirls because it never sources or sinks, it only curls.
Displace geometry with direction. A scalar field says how far to push. A vector field says which way and how far at once, which is what directional bulges, combing and flow-aligned detail need. See Displace.
Paint directions onto points. Sample a field onto a collection to fill in a velocity or facing attribute (
@v,@N) per point. See Attributes.
How to use it
Make one. The Vector Field node generates nothing on its own. It is an operator over whatever you wire into Source, and what it does comes from the type of that wire rather than from a mode you pick first. A fresh node with nothing wired returns zero everywhere.
A scalar or distance field becomes its gradient, the arrows running uphill toward higher values. Direction flips them: Away is the raw gradient, outward from a surface or toward the bright side; Toward is its negative.
A vector field is treated as a potential and curled, which is what makes curl noise: swirl that never sources or sinks. Set Vector Reading to Pass Through to take the field exactly as it arrives instead.
Geometry contributes directions off its surface. Geometry Reading picks Surface Normals, the nearest-surface normal, which follows the triangles, or SDF Gradient, which builds the mesh's own distance field and differentiates it for something smooth and defined everywhere.
A colour field or image is decoded as a normal or flow map. Colour Reading switches that to Brightness Gradient, reading the picture as a heightfield instead, and Flip Y covers the DirectX against OpenGL green-channel convention.
A pen stroke or path becomes flow along the curve. Falloff Radius sets how far that flow reaches, Perpendicular aims it at the curve rather than along it, and Taper By Width drives its strength from the stroke's own width.
A force field lifts straight through, falloff and all.
Source X, Source Y and Source Z take a scalar or distance field each, for building the arrow one component at a time. An unwired one falls back to the matching channel of the decoded Source.
Each reading control appears only while its own type is wired, so there is never a dropdown on screen that cannot apply.
The Source dropdown is a shortcut, not a mode list. Pick Noise and a Noise node is dropped in already wired here; Radial, Vortex and Constant each drop in a Force Field set up as a point attractor, a rotation around an axis, or a uniform push. What arrives is a real node, so its centre, axis and falloff are edited there.
Combine them. Add fields together, blend between two, or scale one up. Layering a little turbulence over a steady wind gives gusty motion.
Read it. Anything downstream samples the field at its own points: a particle at its position, a displace at each vertex, a sample node onto a collection.
A force field and a vector field are the same thing seen from two sides. A directional, point, vortex or turbulence force is a vector field with a falloff envelope around it, so you can build a force or build a raw field and wire it in as one.
Gotcha
Most vector fields are pure formulas and run anywhere. Two do not: flow from a pen stroke and surface normals off a mesh have no direct GPU form, so they are baked into a grid before the GPU can use them, which pins the field to a resolution at that moment. A texture or a Volume is already a GPU texture and is sampled in place, with no bake and no second resolution.
Rasterize bakes the field to a raster at a resolution you set. It only bites on the readings that actually differentiate, the gradients and the curl. A decode, a stroke flow, surface normals and a passed-through field emit their field directly and ignore the toggle.
The arrow has a length as well as a direction. A push that feels too weak or too violent is usually a question of Strength, not of the field's shape. Strength hides itself on the three wirings it cannot affect, surface normals, a lifted force field, and the Pass Through vector reading, because those conversions carry no magnitude of their own.