Fluid iCrowd System - User Documentation

Overview

The Fluid System is an alternative agent distribution and control system that provides three distinct distribution methods and specialized control objects to influence agent movement and behavior.

Distribution

View Mode

  • Render: Standard visualization mode for agent distribution

Terrain Configuration

  • Fluid Terrain: Enable fluid-based terrain interactions

Distribution Types

The system supports three distribution methods:

1. Distribute On Terrain

  • Distributes agents across the entire input terrain surface
  • Weight Paint: Use brush tools to paint distribution density on specific terrain areas
  • Vertex Group Mask: Utilize vertex groups to control agent placement

2. Distribute On Vertex

  • Places agents specifically on mesh vertices
  • Provides precise control over agent positioning

3. Crowd System Distribution

  • Integrates with external crowd systems
  • Takes existing instances and replaces them with dynamic agents
  • Enables migration from static crowds to interactive agent systems

Distribution Parameters

  • Distance Min: Minimum spacing between agents (0.5 m)
  • Density Max: Maximum agent density (1.000)
  • Seed: Randomization seed for distribution patterns (0)

Weight Painting

  • Brush Tool: Interactive painting interface for density control
  • Vertex Group Mask: Use predefined vertex groups as distribution masks

Settings

Speed Thresholds

  • Walk Speed: 0.010 m/s - Agents use walking animation below this speed
  • Run Speed: 1.000 m/s - Agents switch to running animation above this speed
  • Max Speed: 1.000 m/s - Absolute maximum movement speed

Collision Prevention

  • Relax Iterations: 1 iteration - Controls how agents avoid passing through each other
  • Higher values increase collision avoidance quality
  • Lower values improve performance

Control Objects

Three Control Types

Users can input single objects or collections for each control type:

1. Flow Curves

  • Function: Agents follow the tangent direction of curves
  • Zone of Effect: Controlled by curve radius
  • Editing:
  • Select curve points in Edit Mode
  • Use Alt+S to scale radius up or down
  • Larger radius = wider influence area

2. Attracters

  • Function: Pull agents toward the object location
  • Radius Control: Object scale determines attraction area
  • Recommended: Use empty sphere objects for clear visualization

3. Repelers

  • Function: Push agents away from object location
  • Radius Control: Object scale determines repulsion area
  • Recommended: Use empty sphere objects for clear visualization

Agents Configuration

Predefined Agent Collections

  • Male Agents:
  • mem Idle
  • mem Walk
  • mem Run
  • Female Agents:
  • women Idle
  • women Walk
  • women Run

Agent Management

Density Control

  • Probability: 0.500 - Controls spawn likelihood of agent collections

Agent Settings

  • Separate configuration for Male and Female agents
  • Gender-specific behavior and appearance settings

Customization Options

  • Include/Discard: Add or remove agents from simulation
  • Customize Individual Agents: Modify specific agent instances (e.g., man1)
  • Change Clothes: Swap clothing and appearance elements
  • Change Action: Modify animation behaviors
  • Include All: Apply changes to entire agent groups

Custom Agent Creation

  • Object: Reference to agent mesh object
  • Collection: Agent group organization
  • Agent Mesh: 3D model reference
  • Agent Armature: Animation skeleton and rigging
  • Gender: Male/Female classification for behavior rules

Workflow

  1. Distribution Setup:
  2. Choose distribution type (Terrain/Vertex/Crowd System)
  3. Configure density and spacing parameters

  4. Use weight painting for area-specific control

  5. Agent Configuration:

  6. Select agent collections and probabilities
  7. Customize individual agents as needed

  8. Add custom agents if required

  9. Control Placement:

  10. Add Flow Curves for guided movement paths
  11. Place Attracters at points of interest

  12. Use Repelers to block areas or create obstacles

  13. Simulation Tuning:

  14. Adjust speed thresholds for animation transitions
  15. Set relax iterations for collision quality
  16. Fine-tune control object radii and positions

Best Practices

  • Use empty spheres for attracter/repeler objects for clear visualization
  • Test flow curves with varying radii to create natural movement patterns
  • Balance agent density with performance considerations
  • Use weight painting to create realistic concentration areas
  • Start with lower relax iterations and increase if collision issues occur

This Fluid System provides flexible agent distribution and sophisticated movement control, enabling complex crowd simulations with natural-looking behaviors and interactions.