Clutter System — scattering grass, rocks, and debris with GPU instancing

Clutter System — Scattering Grass, Rocks, and Debris

The Clutter System scatters large amounts of small objects (grass, rocks, debris) across a scene using GPU-instanced rendering. It handles placement, streaming, and LOD automatically.

Setup

1. Create a Clutter Definition asset: Asset Browser → Create > Clutter Definition
2. Add a ClutterComponent to a GameObject in your scene
3. Assign the Clutter Definition to the component

Clutter Definition

The definition asset controls what gets scattered and how.

Entries

A list of models or prefabs to scatter. Each entry has a Weight controlling relative spawn probability. Use models for static props (grass, rocks), prefabs when you need components or behaviours.

Scatterer Types

Streaming Settings

• Tile Size — Size of each generation tile (256–4096 units). Larger = fewer jobs, coarser streaming.
• Tile Radius — How many tiles around the camera to keep populated (1–10).

ClutterComponent Modes

// Infinite mode — streams tiles around the camera automatically
var clutter = go.Components.Create<ClutterComponent>();
clutter.ClutterDefinition = myDefinition;
clutter.Mode = ClutterComponent.GenerationMode.Infinite;

// Volume mode — generates within a fixed bounding box, saved with scene
clutter.Mode = ClutterComponent.GenerationMode.Volume;
// Then click Generate in the inspector, or call:
clutter.Generate();

Clutter Tool (Editor)

The Clutter Tool in the editor toolbar lets you paint and erase instances by hand:

• Paint — Left-click to scatter at brush location
• Erase — Ctrl+click to remove within brush radius
• Opacity — Controls density of painted placement (thins out for natural look)

Performance Notes

• GPU instancing means thousands of instances have minimal draw call cost.
• Keep TileRadius low (2–3) for large open worlds.
• Use models (not prefabs) for pure static props — prefabs have component overhead.