BB.Agent2D

Extends BB.Particle2D
Defined in: src/BB.Agent2D.js:13

A 2D Autonomous Agent class for "intelligent" physics behaviors.

Index

Properties

Methods

Constructor

BB.Agent2D
(
  • config
)

Defined in src/BB.Agent2D.js:13

Parameters:

  • config Object

    Agent2D configuration object. Exactly the same configuration object expected in BB.Particle2D.

Example:

 var WIDTH = window.innerWidth;
 var HEIGH = window.innerHeight;
 var agent = new BB.Agent2D({
    maxSpeed: 6,
    position: new BB.Vector2( Math.random() * WIDTH, Math.random() * HEIGHT ),
    velocity: new BB.Vector2(1, 2),
    radius: 50
 });

Properties

acceleration BB.Vector2

Inherited from BB.Particle2D: src/BB.Particle2D.js:99

Usually used to accumulate forces to be added to velocity each frame

elasticity Number default:0.05

Inherited from BB.Particle2D: src/BB.Particle2D.js:135

how bouncy it is when it collides with an object

friction Number default:1

Inherited from BB.Particle2D: src/BB.Particle2D.js:128

the particle's friction ( not environment's friction ) multiplied by velocity each frame

heading Number

Inherited from BB.Particle2D: src/BB.Particle2D.js:154

the particle's "heading" expressed in radians, essentially: Math.atan2( velocity.y, velocity.x );

mass Number default:1

Inherited from BB.Particle2D: src/BB.Particle2D.js:114

the particle's mass

radius Number default:0

Inherited from BB.Particle2D: src/BB.Particle2D.js:121

the particle's radius, used for callculating collistions

speed Number

Inherited from BB.Particle2D: src/BB.Particle2D.js:169

the particle's "speed", essentially: the square root of velocity.x² + velocity.y²

velocity BB.Vector2

Inherited from BB.Particle2D: src/BB.Particle2D.js:56

the particle's velocity ( see acceleration also )

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Methods

align
(
  • particles
  • [maxForce=0.1]
  • [neighborDistance=50]
  • [multiplier=1]
)

Defined in src/BB.Agent2D.js:229

Applies a force that that is the average velocity of all nearby particles(s).

Parameters:

  • particles Array

    An array of BB.Particle2D objects. May also be a single BB.Particle2D object.

  • [maxForce=0.1] Number optional

    The maximum force used to limit the align behavior. Defaults to 0.1 if parameter is null or undefined.

  • [neighborDistance=50] Number optional

    Threshold distance to apply the align behavior. Defaults to 20 if parameter is null or undefined.

  • [multiplier=1] Number optional

    An optional parameter (usually between 0-1.0) used to scale the align force. This multiplier operation is run right before the align force is applied, after the force may have already been limited by maxForce.

Example:

 // assuming agent is an instance of BB.Agent2D
 // assuming particles is an array of BB.Vector2s
 agent.align(particles, 0.1, 50);
 // or to half the align force, use a multiplier
 agent.align(particles, 0.1, 50, 0.5);

applyForce
(
  • vector
)

Inherited from BB.Particle2D: src/BB.Particle2D.js:563

takes a force, divides it by particle's mass, and applies it to acceleration ( which is added to velocity each frame )

Parameters:

avoid
(
  • particles
  • [maxForce]
  • [seperationDistance]
  • [multiplier=1]
)

Defined in src/BB.Agent2D.js:135

Applies a force that steers the agent to avoid particles(s).

Parameters:

  • particles Array

    An array of BB.Particle2D objects. May also be a single BB.Particle2D object.

  • [maxForce] Number optional

    The maximum force used to limit the avoid behavior. Defaults to 0.1 if parameter is null or undefined.

  • [seperationDistance] Number optional

    Threshold distance to apply the avoid behavior. Defaults to 20 if parameter is null or undefined.

  • [multiplier=1] Number optional

    An optional parameter (usually between 0-1.0) used to scale the avoid force. This multiplier operation is run right before the avoid force is applied, after the force may have already been limited by maxForce.

Example:

 // assuming agent is an instance of BB.Agent2D
 // assuming particles is an array of BB.Particle2Ds
 agent.avoid(particles, 0.1, 100);
 // or to half the avoid force, use a multiplier
 agent.avoid(particles, 0.1, 100, 0.5);

avoidWalls
(
  • config
)

Defined in src/BB.Agent2D.js:368

Causes the agent to steer away from a rectangular bounding box. Must be run once per frame.

Parameters:

  • config Object

    The config object.

    • top Number

      The top of the bounding box.

    • bottom Number

      The bottom of the bounding box.

    • left Number

      The left of the bounding box.

    • right Number

      The right of the bounding box.

    • distance Number

      The threshold distance inside of which the avoidWalls force will be applied to the agent.

    • [maxForce=0.1] Number optional

      The maximum force used to limit the avoidWalls behavior. Defaults to 0.1 if parameter is null or undefined.

Example:

 // assuming agent is an instance of BB.Agent2D
 agent.avoidWalls({
    top: 0,
    bottom: window.innerHeight,
    left: 0,
    right: window.innerWidth,
    distance: 100,
    maxForce: 0.1
 });

cohesion
(
  • particles
  • [maxForce=0.1]
  • [neighborDistance=50]
  • [multiplier=1]
)

Defined in src/BB.Agent2D.js:305

Applies a steering force that is the average position of all nearby particles(s).

Parameters:

  • particles Array

    An array of BB.Particle2D objects. May also be a single BB.Particle2D object.

  • [maxForce=0.1] Number optional

    The maximum force used to limit the cohesion behavior. Defaults to 0.1 if parameter is null or undefined.

  • [neighborDistance=50] Number optional

    Threshold distance to apply the cohesion behavior. Defaults to 20 if parameter is null or undefined.

  • [multiplier=1] Number optional

    An optional parameter (usually between 0-1.0) used to scale the cohesion force. This multiplier operation is run right before the cohesion force is applied, after the force may have already been limited by maxForce.

Example:

 // assuming agent is an instance of BB.Agent2D
 // assuming particles is an array of BB.Vector2s
 agent.cohesion(particles, 0.1, 50);
 // or to half the cohesion force, use a multiplier
 agent.cohesion(particles, 0.1, 50, 0.5);

collide
(
  • config
)

Inherited from BB.Particle2D: src/BB.Particle2D.js:375

tracks objects to collide against, this can be other particles ( objects with position vectors and a radius ) and/or a perimeter ( top, left, right, bottom )

Parameters:

  • config Object

    object with properties for top, left, bottom, right ( all numbers ) and particles ( array of other particles or objects with position.x, positon.y and radius properties )

Example:

  // assuming ball is an instance of BB.Particle2D
  // assuming balls is an array of BB.Particle2D objects
  ball.collide({
     top:0,
     right: canvas.width,
     bottom: canvas.height,
     left: 0,
     particles: balls
  });

flee
(
  • targets
  • [maxForce=0.1]
  • [multiplier=1]
)

Defined in src/BB.Agent2D.js:113

Applies a force that steers the agent away from particles(s). Opposite of seek.

Parameters:

  • targets Array

    An array of BB.Vector2 objects. May also be a single BB.Vector2 object.

  • [maxForce=0.1] Number optional

    The maximum force used to limit the flee behavior. Defaults to 0.1 if parameter is null or undefined.

  • [multiplier=1] Number optional

    An optional parameter (usually between 0-1.0) used to scale the flee force. This multiplier operation is run right before the flee force is applied, after the force may have already been limited by maxForce.

Example:

 // assuming agent is an instance of BB.Agent2D
 // assuming targets is an array of BB.Vector2s
 agent.flee(targets, 0.1);
 // or to half the flee force, use a multiplier
 agent.flee(targets, 0.1, 0.5);

gravitate
(
  • particle
  • [mass]
)

Inherited from BB.Particle2D: src/BB.Particle2D.js:187

identifies something to gravitate towards. the object of gravitation needs to have a position ( x, y ) and mass

Parameters:

  • particle Object

    if passed as the only argument it should be an Object with a position.x, position.y and mass ( ie. an instance of BB.Particle2D ). Otherwise the first argument needs to be an Object with an x and y ( ie. instance of BB.Vector2 or at the very least { x: ..., y: ... } )

    alternatively, gravitate could also be passed an array of objects ( each with position and mass properties )

  • [mass] Number optional

    when particle is not an instance of BB.Particle2D and is a Vector an additional argument for mass is required

Example:

  // assuming star and planet are both instances of BB.Particle2D
  planet.gravitate( star );
  // or
  planet.gravitate( star.position, star.mass );
  // or
  planet.gravitate( { x:WIDTH/2, y:HEIGHT/2 }, 20000 );

  // assuming stars is an array of BB.particle2D
  planet.gravitate( stars );

seek
(
  • targets
  • [maxForce=0.1]
  • [arriveDistance]
  • [multiplier=1]
)

Defined in src/BB.Agent2D.js:42

Applies a force that steers the agent towards target(s). Opposite of flee.

Parameters:

  • targets Array

    An array of BB.Vector2 objects. May also be a single BB.Vector2 object.

  • [maxForce=0.1] Number optional

    The maximum force used to limit the seek behavior. Defaults to 0.1 if parameter is null or undefined.

  • [arriveDistance] Number optional

    Threshold distance to apply the arrive behavior. If a non-null/undefined value is supplied, the agent will slow its movement porportionate to its distance from a target if it is within this distance from that target.

  • [multiplier=1] Number optional

    An optional parameter (usually between 0-1.0) used to scale the seek force. This multiplier operation is run right before the seek force is applied, after the force may have already been limited by maxForce.

Example:

 // assuming agent is an instance of BB.Agent2D
 // assuming targets is an array of BB.Vector2s
 agent.seek(targets, 0.1, 200);

seperate
(
  • particles
  • [maxForce]
  • [seperationDistance]
  • [multiplier=1]
)

Defined in src/BB.Agent2D.js:213

Alias of avoid(). Applies a force that steers the agent to avoid particles(s).

Parameters:

  • particles Array

    An array of BB.Particle2D objects. May also be a single BB.Particle2D object.

  • [maxForce] Number optional

    The maximum force used to limit the avoid behavior. Defaults to 0.1 if parameter is null or undefined.

  • [seperationDistance] Number optional

    Threshold distance to apply the avoid behavior. Defaults to 20 if parameter is null or undefined.

  • [multiplier=1] Number optional

    An optional parameter (usually between 0-1.0) used to scale the avoid force. This multiplier operation is run right before the avoid force is applied, after the force may have already been limited by maxForce.

spring
(
  • config
)

Inherited from BB.Particle2D: src/BB.Particle2D.js:289

identifies something to spring towards. the target needs to have an x,y position, a k value which is a constant factor characteristic of the spring ( ie. its stiffness, usually some decimal ), and a length.

Parameters:

  • config Object

    object with properties for point ( vector with x,y ), k ( number ) and length ( number ).

    alternatively, spring could also be passed an array of config objects

Example:

  // assuming ball is an instance of BB.Particle2D
  // and center is an object with x,y positions
  ball.spring({
     position: center.position,
     k: 0.1,
    length: 100
  });
 
  // the ball will spring back and forth forever from the center position
  // unless ball has friction value below the default of 1.0

update ()

Inherited from BB.Particle2D: src/BB.Particle2D.js:440

Update the particle's internals and apply acceleration to veloicty. Called once per animation frame.

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