Using Attractors

Introduction

How characters move around a scene and what they are interested in (attraction) are handled in a probabilistic way that mimics the behaviour of people in the real world.

You find the Attractor element in the helpers section of assets. When placed it creates an area that will be influenced by the attractor settings placed into a scene that affect the behaviour of elements according to the interaction of the properties of the attractors and certain properties of the elements themselves. Free-standing attractor objects can be placed anywhere in the scene and will appear in an 'attractors' field in the scenario file; attractors can also be attached to objects in the scenario and will appear in an 'attractor' field of the object to which they are attached.
An object may have only one attached attractor.

Actors are the only elements affected by attractors. An actor can be given an interest in any number of attractors.

Features

(Fig.1) Helpers

Editor_ Scene Functions - Generator - Helper - Attractor.png

Assets

Helpers Attractors

### (Fig.2) Attractor

Editor_ Scene Functions - Scenario - Attractor.png

Attractor Settings: Attractiveness - Attractiveness can also be used to repel by using a minus figure. Uses a value between -1.0 to 1.0; Decay - Decreases or increases the attractiveness of the attractor to zero for as long as the scenario/pass runs.; Influence Radius Start - Inner circle, anything within this area will not be attracted; Influence Radius End - Outer circle, anything without this area will not be attracted; Direction - Only used when spread is below 360. Sets the centre point of the chunk that isn't covered in degrees.; Spread - Radius the cloud camera moves within in degrees.; Retentiveness - This value is how long an asset will dwell in the attractors influence area in seconds; Randomness - will randomise the attractiveness of the attractor; Activate Delay - Length of time the attractor is dormant within the scenario/pass; Group Name - You can use a group name to chain attractors together; Remove All Behavior - Removes all behaviors added to the attractor; Add A New Behavior - Create a new behavior for this attractor. Editor - Using Behaviors

Explanation

Attractiveness

Is a value between -1.0 and 1.0. The attractiveness of each attractor is combined with its influence radius and the Interest Level of an actor to calculate the likelihood that it will navigate towards and dwell at any given attractor. A value of less than 1 will repel characters with increasing urgency until a value of -1.0 indicates panic.

Decay

When you want the attractiveness of an attractor to become less attractive or less panic as it takes the attractiveness to zero over the time of your scenario/pass. This can either be linear or you can use one of four easing options, which are illustrated below.

Easing function.png

Influence Area

To set the area of influence there are four settings. An inner setting (Influence Radius Start), an outer setting (Influence Radius End), that are measured in meters, a spread which is in degrees and a direction also in degrees. Direction is only used if spread has a value, the direction angle will be the centre of the remaining radius. The illustration below shows this.

Radius Spread Direction.png

Randomness

This is a value between 0 and 1. By default it is set to zero, so every element is affect the same. When set to 0.5 around half the elements in the attractor will be affected by it, set to 1 it will be a rare an element will be attracted. It may also effect how long an element will dwell in the attractor area.

Creating a attractor

Go to the Assets menu (Fig.1-1), open the helpers dropdown and select MT_Attractor or MT_AttractorPanic (Fig.1-2)
Once selected, place the attractor in the desired location. This will draw the area the attractor is affecting. Anything outside this area will not be affected.