Yusuf's Thoughts

Vector Field Instancing

3 min read

Inspired by: Okamirufu Vizualizer

Create a dense, swirling 3D field where millions of individual points follow a fluid-like path. This is the foundation of many generative art “vortex” effects.

Operator Families in this Recipe

  • POPs (Point Operators): Creating and animating the vector field.
  • SOPs (Surface Operators): The base geometry for instancing.
  • COMPs (Components): Managing the 3D scene and rendering.

Part 1: High-Density 3D Grid

  1. The Container: Create a Geo COMP and enter it.
  2. The POP Bridge: Create a POP SOP. Double-click to enter the POP network.
  3. The Base: Add a Grid POP.
    • Size → 5, 5, 5.
    • Rows/Columns/Layers → 50, 50, 50. This creates 125,000 base points.
  4. The Force Field: Add a Noise POP.
    • Output Tab → Set “Output” to Offset Position or Velocity.
    • Noise Tab → Set “Monochrome” to Off. This generates unique X, Y, and Z vectors for each point.
    • Amplitude → 0.5.
    • Period → 2.0.
  5. The Motion: Animate the Transform (Translate Z) of the Noise POP using absTime.seconds * 0.1 to make the field “flow” over time.

Part 2: Instancing Tiny Geometry

Instead of rendering simple points, we can instance 3D geometry onto every point in the field.

  1. The Instance Source: Connect your POP SOP to the Instancing Tab of your Geo COMP.
  2. The Shape: Create a Sphere SOP (set to “Mesh” and low frequency) or a small Box SOP.
  3. Enable Instancing: Turn on “Instancing” in the Geo COMP.
    • Translate X/Y/Z → Use the P(0), P(1), and P(2) attributes from the POP SOP.
    • Scale X/Y/Z → Map to the Noise POP’s output to make instances shrink and grow as they move.

Part 3: Shading & Lighting

  1. Apply a Constant MAT or a PBR MAT to the Geo COMP.
  2. Point Coloring: In the POP network, add an Attribute POP to set the Cd (Color) attribute based on the point’s velocity. This makes fast-moving particles glow brighter.
  3. The Look: Combine this with the Post-Processing Recipe for a high-end generative aesthetic.

Part 4: Interactive Control

  • Connect an Audio File In CHOP to the Noise POP’s Amplitude.
  • Now, the entire field will “pulse” or “vibrate” in sync with the beat, creating a powerful audio-visual experience.

Parameter Tuning & Behavior

ParameterBehavior
Grid DivisionsHigher = more dense vortex (very high counts require GPU instancing); Lower = sparse field.
Noise AmplitudeHigher = more violent, wide-sweeping swirls; Lower = tight, subtle movement.
Noise PeriodHigher = larger, lazier “wind” patterns; Lower = small, chaotic, “jittery” eddies.
Noise SpeedHigher = faster evolution of the field; Lower = slow, hypnotic flow.
Audio SensitivityHigher = field “vibrates” more intensely to sound; Lower = subtle, rhythmic pulsing.

Network Architecture

To visualize how the data flows, here is a map of the final network:

[ POP NETWORK ]
Grid POP (50x50x50)
      │
      ▼
Noise POP (Vector Mode: Offset Pos)
      │
      ▼
Attribute POP (Velocity to Color)
      │
      ▼
[ POP SOP ] ───────┐
                   │ (Data Source)
                   ▼
[ Sphere SOP ] ──▶ [ Geo COMP ] ───▶ [ Render TOP ]
                   (Instancing On)

Data Flow Explanation

  1. Field Creation: The Grid POP creates a dense 3D space of points.
  2. Forces: The Noise POP is set to “Vector Mode,” which means it generates three values (X, Y, Z) for every point. This becomes the “current” or “wind” that drives the vortex.
  3. Visualization: Instead of rendering the points directly, we use the POP SOP as a “template.” The Geo COMP looks at this template and places a Sphere SOP at every point’s location.
  4. Scaling: Because the Noise POP is animated, the “current” shifts, making all 125,000 spheres swirl in unison.

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