Reusable procedural systems. Parametric assets. Performance-aware instancing.
When to Use
- Scatter systems (rocks, vegetation, debris)
- Parametric buildings, roads, pipes, cables
- Procedural variation without unique modeling
- Kit assembly with randomization
- Non-destructive iteration on large scenes
Workflow
Define Parameters → Build Node Tree → Create Node Group (GN_)
→ Test Variations → Bake/Instance Decision → Export Integration
Node Group Standards
- Prefix:
GN_[System]_[Descriptor] - Expose only necessary inputs (seed, density, scale range)
- Document input ranges in group name or custom properties
- Version node groups:
GN_Scatter_Rocks_v02
Core Patterns
Scatter System
Mesh Surface → Distribute Points on Faces → Instance on Points
→ Randomize Rotation (Z) → Randomize Scale → Realize (optional)
Building Generator
Floor Count (input) → Repeat Mesh → Stack Instances
→ Window Cut Pattern → Material Variation → Output
Cable/Pipe Routing
Curve Input → Curve to Mesh (profile) → Subdivide → Set Material
→ Multiple curves from single path node
Rock Formation
Ico Sphere → Displace (noise) → Decimate → Instance Scatter
Randomization
| Parameter | Typical Range |
|---|---|
| Scale | 0.8–1.2 (uniform or per-axis) |
| Rotation Z | 0–360° |
| Density | 0.1–2.0 per m² |
| Seed | Integer for reproducibility |
Always expose seed as group input for art direction iteration.
Performance Rules
| Scenario | Approach |
|---|---|
| Game export | Realize instances → decimate → export mesh |
| Background scatter | Keep instanced; limit count |
| Hero procedural | Bake to static mesh for engine |
| Viewport preview | Limit instance count attribute |
Reusable Systems Library
| Group | Purpose |
|---|---|
| GN_Scatter_Objects | Generic surface scatter |
| GN_Array_Modular | Linear modular repetition |
| GN_Curve_Pipe | Pipe/cable along curve |
| GN_Wall_Variant | Parametric wall sections |
| GN_Vegetation_Cluster | Tree/bush clustering |
MCP Integration
- Create geometry nodes modifier via MCP
- Configure group inputs via MCP
- Query instance count and final polycount
- Realize geometry for export via MCP
- Organize GN objects in dedicated collection
Integration with Export
Before export:
- Apply geometry nodes modifier OR
- Realize instances and merge OR
- Export as instances if engine supports (Unreal HISM)
Document which approach per target engine.
Constraints
MUST DO
- Create reusable node groups, not one-off trees
- Expose seed and density as inputs
- Test at min/max parameter extremes
- Realize/bake before game export unless engine supports instances
- Name groups with
GN_prefix
MUST NOT DO
- Million-instance scatter without LOD/culling plan
- Nested realize operations (performance killer)
- Hardcode values that should be inputs
- Export procedural without polycount validation
- Skip variation testing at boundary values
Reference Guide
| Topic | Reference | Load When |
|---|---|---|
| Scatter recipes | references/scatter-systems.md |
Environment scatter |
| Building generators | references/building-generators.md |
Architectural procedural |