/// <summary>Run the three primary rules of boidom.</summary>
/// <param name="boid">The boid to process.</param>
/// <returns>The velocity vector resulting from the three primary rules and their associated weights.</returns>
private Vector3D PrimaryRules_1_2_3(Boid boid)
{
int numNearby = 0;
Vector3D summedPosition = new Vector3D();
Vector3D summedVelocity = new Vector3D();
Vector3D summedSeparation = new Vector3D();
// For rule #1, we want the boid to fly towards the center of all of those in its neighborhood.
// We find all of those boids, average their positions, and create a velocity vector to move the
// boid a bit of the way there.
// For rule #2, we want the boid to move away from each other boid it's a bit too close to.
// Find all of those boids in its immediate vicinity, and push it away.
// For rule #3, we want the boid to match velocities with those boids in its neighborhood.
// Sum their velocities, find the average, and move this boid's velocity a bit in that direction.
foreach (var other in m_boidModels)
{
if (other != boid &&
(other.PreviousPosition - boid.PreviousPosition).Length <= NEIGHBORHOOD_SIZE &&
boid.ComputeAngle(other) <= 135)
{
summedPosition += other.PreviousPosition;
summedVelocity += other.PreviousVelocity;
numNearby++;
if ((other.PreviousPosition - boid.PreviousPosition).Length < MIN_DISTANCE_FROM_NEIGHBOR)
{
summedSeparation -= (other.PreviousPosition - boid.PreviousPosition);
}
}
}
var rule1_flyTowardsCenter = (numNearby > 0 ? (summedPosition - boid.PreviousPosition) / numNearby : new Vector3D()) * PERCENTAGE_TO_MOVE_TOWARDS_AVERAGE_POSITION;
var rule2_separateFromNearby = summedSeparation;
var rule3_matchVelocities = (numNearby > 0 ? (summedVelocity - boid.PreviousVelocity) / numNearby : new Vector3D()) * PERCENTAGE_TO_MOVE_TOWARDS_AVERAGE_VELOCITY;
return
((m_rule1Weight * rule1_flyTowardsCenter) +
(m_rule2Weight * rule2_separateFromNearby) +
(m_rule3Weight * rule3_matchVelocities));
}
/// <summary>Encourage a boid to stay within its aviary.</summary>
/// <param name="boid">The boid.</param>
/// <returns>The velocity vector encouraging a boid to stay within its bounds.</returns>
private Vector3D Rule4_EncourageStayingWithinAviary(Boid boid)
{
var v = new Vector3D();
// X
if (boid.PreviousPosition.X < m_aviary.X)
{
v.X = m_aviary.X - boid.PreviousPosition.X;
}
else if (boid.PreviousPosition.X > m_aviary.X + m_aviary.SizeX)
{
v.X = (m_aviary.X + m_aviary.SizeX) - boid.PreviousPosition.X;
}
// Y
if (boid.PreviousPosition.Y < m_aviary.Y)
{
v.Y = m_speedLimit;
}
else if (boid.PreviousPosition.Y > m_aviary.Y + m_aviary.SizeY)
{
v.Y = (m_aviary.Y + m_aviary.SizeY) - boid.PreviousPosition.Y;
}
// Z
if (boid.PreviousPosition.Z < m_aviary.Z)
{
v.Z = m_aviary.Z - boid.PreviousPosition.Z;
}
else if (boid.PreviousPosition.Z > m_aviary.Z + m_aviary.SizeZ)
{
v.Z = (m_aviary.Z + m_aviary.SizeZ) - boid.PreviousPosition.Z;
}
return(v * PERCENTAGE_TO_MOVE_TOWARDS_INBOUNDS);
}
/// <summary>Encourage a boid to stay close to its home position.</summary>
/// <param name="boid">The boid.</param>
/// <returns>The velocity vector encouraging a boid to stay at home.</returns>
private Vector3D Rule5_TendendcyTowardsHome(Boid boid)
{
return((m_home - boid.PreviousPosition) * PERCENTAGE_TO_MOVE_TOWARDS_HOME);
}
