class Boid

# File examples/ruboids/ruboids/Boid.rb, line 18
def initialize(pos = nil)
    super(pos, nil)
    init
end

# File examples/ruboids/ruboids/Boid.rb, line 75
def avoidOthers()
    c = Point.new()
    @flock.members.each { | b |
        if b != self
            otherPos = b.position
            if @position.squareOfDistanceTo(otherPos) <
                    $PARAMS['boid_square_of_personal_space_dist']
                c.addPoint(@position)
                c.subtractPoint(otherPos)
            end
        end
    }
    @vector.addPoint(c)
end

# File examples/ruboids/ruboids/Boid.rb, line 104
def boundPosition()
    v = Point.new

    halfWidth = $PARAMS['world_width'] / 2
    halfHeight = $PARAMS['world_height'] / 2
    halfDepth = $PARAMS['world_depth'] / 2

    if position.x < -halfWidth
        v.x = $PARAMS['boid_bounds_limit_pull']
    elsif position.x > halfWidth
        v.x = -$PARAMS['boid_bounds_limit_pull']
    end

    if position.y < -halfHeight + almostGroundLevel +
            $PARAMS['boid_bounds_limit_above_ground_level']
        v.y = $PARAMS['boid_bounds_limit_pull']
    elsif position.y > halfHeight
        v.y = -$PARAMS['boid_bounds_limit_pull']
    end

    if position.z < -halfDepth
        v.z = $PARAMS['boid_bounds_limit_pull']
    elsif position.z > halfDepth
        v.z = -$PARAMS['boid_bounds_limit_pull']
    end

    @vector.addPoint(v)
end

# File examples/ruboids/ruboids/Boid.rb, line 23
def init
    @maxSpeed = $PARAMS['boid_max_speed']
    @maxSpeedSquared = @maxSpeed * @maxSpeed
    @flock = nil           # set by flock when flock adds to self
    @wingFlapPos = rand(7)
    @perchingTurnsLeft = 0
    @almostGroundLevel = 5.0

    @view = BoidView.new(self)
end

# File examples/ruboids/ruboids/Boid.rb, line 133
def limitSpeed()
    speedSquared = Point::ORIGIN.squareOfDistanceTo(@vector)
    if speedSquared > @maxSpeedSquared
        f = Math.sqrt(speedSquared) * @maxSpeed
        @vector.divideBy(f)
    end
end

# File examples/ruboids/ruboids/Boid.rb, line 90
def matchOthersVelocities()
    vel = Point.new()
    flock.members.each { | b |
        if b != self
            vel.addPoint(b.vector)
        end
    }
    vel.divideBy(flock.members.length - 1)
    vel.subtractPoint(@vector)
    vel.divideBy(8)

    @vector.addPoint(vel)
end

# File examples/ruboids/ruboids/Boid.rb, line 34
def move
    # Flap wings. Only flap occasionally if not perching.
    if (@perchingTurnsLeft == 0 ||
        rand(100) < $PARAMS['boid_perch_wing_flap_percent'])
        @wingFlapPos = (@wingFlapPos + 1) & 7
    end

    if @perchingTurnsLeft > 0
        # Only take off when wing flap position == 2.
        if --@perchingTurnsLeft == 0 && @wingFlapPos != 2
            @perchingTurnsLeft = (8 + 2 - @wingFlapPos) & 7
            return
        end
    end

    moveTowardsFlockCenter()
    avoidOthers()
    matchOthersVelocities()
    boundPosition()
    limitSpeed()

    super()                        # Add velocity vector to position.

    # Boids at ground level perch for a while.
    if @position.y < @almostGroundLevel
        @position.y = @almostGroundLevel
        @vector.x = @vector.y = @vector.z = 0
        @perchingTurnsLeft =
            rand($PARAMS['boid_max_perching_turns'])
    end
end

# File examples/ruboids/ruboids/Boid.rb, line 66
def moveTowardsFlockCenter()
    flockCenter = @flock.centerExcluding(self)
    flockCenter.subtractPoint(@position)
    # Move 1% of the way towards the center
    flockCenter.divideBy(100.0)

    @vector.addPoint(flockCenter)
end