pixelheros/docs/engine-reference/unreal/plugins/pcg.md

Unreal Engine 5.7 — PCG (Procedural Content Generation)

Last verified: 2026-02-13 Status: Production-Ready (as of UE 5.7) Plugin: PCG (built-in, enable in Plugins)

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Overview

Procedural Content Generation (PCG) is Unreal's node-based framework for generating procedural content at massive scale. It's designed for populating large open worlds with foliage, rocks, props, buildings, and other environmental detail.

Use PCG for:

• Procedural foliage placement (trees, grass, rocks)
• Biome-based environment generation
• Road/path generation
• Building/structure placement
• World detail population (props, clutter)

DON'T use PCG for:

• Gameplay logic (use Blueprints/C++)
• One-off manual placement (use editor tools)

⚠️ Note: PCG was experimental in UE 5.0-5.6, became production-ready in UE 5.7.

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Core Concepts

1. PCG Graph

• Node-based graph (similar to Material Editor)
• Defines generation rules

2. PCG Component

• Placed in level, executes PCG Graph
• Generates content in defined volume

3. PCG Data

• Point data (positions, rotations, scales)
• Spline data (paths, roads, rivers)
• Volume data (density, biome masks)

4. Nodes

• Samplers: Generate points (Grid, Poisson, Surface)
• Filters: Remove points based on rules (Density, Tag, Bounds)
• Modifiers: Transform points (Offset, Rotate, Scale)
• Spawners: Instantiate meshes/actors at points

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Setup

1. Enable Plugin

Edit > Plugins > PCG > Enabled > Restart

2. Create PCG Volume

1. Place Actors > Volumes > PCG Volume
2. Scale volume to desired generation area

3. Create PCG Graph

1. Content Browser > PCG > PCG Graph
2. Open PCG Graph Editor

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Basic Workflow

Example: Forest Generation

1. Create PCG Graph

Node Setup:

Input (Volume)
  ↓
Surface Sampler (sample volume surface, points per m²: 0.5)
  ↓
Density Filter (use texture mask or noise)
  ↓
Static Mesh Spawner (tree meshes)
  ↓
Output

2. Assign Graph to Volume

1. Select PCG Volume
2. Details Panel > PCG Component > Graph = Your PCG Graph
3. Click "Generate" button

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Key Node Types

Samplers (Point Generation)

Grid Sampler

• Regular grid of points
• Configure:
  • Grid Size: Distance between points
  • Offset: Random offset per point

Poisson Disk Sampler

• Random points with minimum distance
• Configure:
  • Points Per m²: Density
  • Min Distance: Spacing between points

Surface Sampler

• Points on mesh surfaces or landscape
• Configure:
  • Points Per m²: Density
  • Surface Only: Only surface, not volume

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Filters (Point Removal)

Density Filter

• Remove points based on density value
• Input: Texture or noise
• Use for: Biome masks, clearings, paths

Tag Filter

• Filter points by tag
• Use for: Conditional spawning

Bounds Filter

• Keep only points within bounds
• Use for: Limiting generation to specific areas

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Modifiers (Point Transformation)

Rotate

• Randomize point rotation
• Configure:
  • Min/Max Rotation: Rotation range per axis

Scale

• Randomize point scale
• Configure:
  • Min/Max Scale: Scale range

Project to Ground

• Snap points to landscape surface

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Spawners (Mesh/Actor Instantiation)

Static Mesh Spawner

• Spawn static meshes at points
• Configure:
  • Mesh List: Array of meshes (random selection)
  • Culling Distance: LOD/culling settings

Actor Spawner

• Spawn Blueprint actors at points
• Use for: Gameplay actors, interactive objects

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Data Sources

Landscape

• Use landscape as input for sampling
• Automatically projects to landscape height

Splines

• Generate content along splines (roads, rivers, paths)
• Example: Trees along path

Textures

• Use textures as density masks
• Paint biomes, clearings, areas

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Biome Example (Mixed Forest)

Graph Setup

Input (Landscape)
  ↓
Surface Sampler (density: 1.0)
  ↓
┌─────────────────┬─────────────────┐
│ Tree Biome      │ Rock Biome      │
│ (density > 0.5) │ (density < 0.5) │
├─────────────────┼─────────────────┤
│ Tree Spawner    │ Rock Spawner    │
└─────────────────┴─────────────────┘
  ↓
Merge
  ↓
Output

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Spline-Based Generation (Road with Trees)

1. Create PCG Graph

Spline Input
  ↓
Spline Sampler (sample along spline)
  ↓
Offset (offset from spline path)
  ↓
Tree Spawner
  ↓
Output

2. Add Spline Component to PCG Volume

1. PCG Volume > Add Component > Spline
2. Draw spline path
3. PCG Graph reads spline data

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Runtime Generation

Trigger Generation from C++

#include "PCGComponent.h"

UPCGComponent* PCGComp = /* Get PCG Component */;
PCGComp->Generate(); // Execute PCG graph

Stream Generation (Large Worlds)

• PCG automatically streams with World Partition
• Only generates content in loaded cells

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Performance

Optimization Tips

• Use culling distance on spawned meshes (LOD)
• Limit density (fewer points = better performance)
• Use Hierarchical Instanced Static Meshes (HISM) for repeated meshes
• Enable streaming for large worlds

Debug Performance

// Console commands:
// pcg.graph.debug 1 - Show PCG debug info
// stat pcg - Show PCG performance stats

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Common Patterns

Forest with Clearings

Surface Sampler
  ↓
Density Filter (noise texture with clearings)
  ↓
Tree Spawner (pine, oak, birch)

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Rocks on Steep Slopes

Landscape Input
  ↓
Surface Sampler
  ↓
Slope Filter (angle > 30°)
  ↓
Rock Spawner

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Props Along Road

Spline Input (road spline)
  ↓
Spline Sampler
  ↓
Offset (side of road)
  ↓
Street Light Spawner

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Debugging

PCG Debug Visualization

// Console commands:
// pcg.debug.display 1 - Show points and generation bounds
// pcg.debug.colormode points - Color-code points

Graph Debugging

• PCG Graph Editor > Debug > Show Debug Points
• Visualize points at each node in the graph

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Migration from UE 5.6 (Experimental) to 5.7 (Production)

API Changes

// ❌ OLD (5.6 experimental API):
// Some nodes renamed, API unstable

// ✅ NEW (5.7 production API):
// Stable node types, documented API

Migration: Rebuild PCG graphs using stable 5.7 nodes. Test thoroughly.

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Limitations

• Not for gameplay logic: Use Blueprints/C++ for game rules
• Large graphs can be slow: Optimize with filters and density reduction
• Runtime generation overhead: Pre-generate when possible

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Sources

• https://docs.unrealengine.com/5.7/en-US/procedural-content-generation-in-unreal-engine/
• https://docs.unrealengine.com/5.7/en-US/pcg-quick-start-in-unreal-engine/
• UE 5.7 Release Notes (PCG Production-Ready announcement)