//Cohesion produces a steering force that moves a vehicle toward the center of mass of its neighbors
//A sheep running after its flock is demonstrating cohesive behavior. Use this force to keep a group of vehicles together.
public static Vector2 Cohesion(ref Vehicle[] allCars, Vehicle me, Vector2 currentPosition, Vector2 velocity, int max_speed, int cohesionRadius)
{
int j = 0;
Vector2 averagePosition = Vector2.Zero;
Vector2 distance = Vector2.Zero;
for (int i = 0; i < allCars.Length; i++)
{
distance = Vector2.Subtract(currentPosition, allCars[i].CurrentPosition);
if (VectorHelpers.Length(distance) < cohesionRadius && allCars[i] != me)
{
j++;
averagePosition = Vector2.Add(averagePosition, allCars[i].CurrentPosition);
}
}
if (j == 0)
{
return(Vector2.Zero);
}
else
{
averagePosition = averagePosition / j;
return(Seek(ref averagePosition, ref currentPosition, ref velocity, max_speed));
}
}
//Alignment attempts to keep a vehicle's heading aligned with its neighbors
//The force is calculated by first iterating through all the neighbors and averaging their heading vectors.
//This value is the desired heading, so we just subtract the vehicle's heading to get the steering force.
public static Vector2 Alignment(ref Vehicle[] allCars, Vehicle me, ref Vector2 currentPosition, ref Vector2 velocity, int max_speed)
{
int j = 0;
Vector2 averageDirection = new Vector2(0);
Vector2 distance = new Vector2(0);
for (int i = 0; i < allCars.Length; i++)
{
distance = Vector2.Subtract(currentPosition, allCars[i].CurrentPosition);
if (VectorHelpers.Length(distance) < 100 && allCars[i] != me)
{
j++;
averageDirection = Vector2.Add(averageDirection, allCars[i].Velocity);
}
}
if (j == 0)
{
return(Vector2.Zero);
}
else
{
averageDirection = averageDirection / j;
return(Vector2.Subtract(averageDirection, velocity));
}
}
//Separation creates a force that steers a vehicle away from those in its neighborhood region.
//When applied to a number of vehicles, they will spread out, trying to maximize their distance from every other vehicle
public static Vector2 Separation(ref Vehicle[] allCars, Vehicle me, ref Vector2 currentPosition, ref Vector2 velocity, int max_speed)
{
int j = 0;
Vector2 separationForce = new Vector2(0);
Vector2 averageDirection = new Vector2(0);
Vector2 distance = new Vector2(0);
for (int i = 0; i < allCars.Length; i++)
{
distance = Vector2.Subtract(currentPosition, allCars[i].CurrentPosition);
if (VectorHelpers.Length(distance) < 100 && allCars[i] != me)
{
j++;
separationForce += Vector2.Subtract(currentPosition, allCars[i].CurrentPosition);
separationForce = Vector2.Normalize(separationForce);
separationForce = Vector2.Multiply(separationForce, 1 / .7f);
averageDirection = Vector2.Add(averageDirection, separationForce);
}
}
if (j == 0)
{
return(Vector2.Zero);
}
else
{
//averageDirection = averageDirection / j;
return(averageDirection);
}
}
//Flee is the opposite of seek. Instead of producing a steering force to steer the agent toward a target position, flee creates a force that steers the agent away.
public static Vector2 Flee(ref Vector2 targetPosition, ref Vector2 currentPosition, ref Vector2 Velocity, int max_speed, int FOV, int vehicleNo)
{
if (VectorHelpers.Length(Vector2.Subtract(targetPosition, currentPosition)) > FOV)
{
return(Vector2.Zero);
}
Vector2 desired_V = Vector2.Normalize(Vector2.Subtract(currentPosition, targetPosition)) * max_speed;
return(Vector2.Subtract(desired_V, Velocity));
}
//=========================================================//
//calculate force and update position
private void UpdatePosition(ref Vector2 targetPosition)
{
heading = Vector2.Normalize(velocity);
switch (SB)
{
case SB.None:
steerForce = Vector2.Zero;
break;
case SB.Seek:
steerForce = SteeringBehaviours.Seek(ref targetPosition, ref currentPosition, ref velocity, max_speed);
break;
case SB.Flee:
steerForce = SteeringBehaviours.Flee(ref targetPosition, ref currentPosition, ref velocity, max_speed, FOV, vehicleNo);
break;
case SB.Arrive:
steerForce = SteeringBehaviours.Arrive(ref targetPosition, ref currentPosition, ref velocity, ArriveRadius, max_speed, vehicleNo);
break;
case SB.Pursuit:
break;
case SB.Evade:
break;
case SB.Wander:
steerForce = SteeringBehaviours.Wander(ref wanderTarget, ref currentPosition, ref velocity, ref heading, WanderRadius, WanderDistance, WanderJitter);
break;
case SB.PathFollowing:
if (!enableSpecialPath)
{
steerForce = SteeringBehaviours.PathFollowing(ref targetPosition, ref currentPosition, ref velocity, ref pathPoints, ref currentPathPoint, maxPathPoints, max_speed);
}
else
{
steerForce = SteeringBehaviours.PathFollowing(ref targetPosition, ref currentPosition, ref velocity, ref specialPathPoints, ref currentPathPoint, maxSpecialPathPoints, max_speed);
}
break;
case SB.Cohesion:
steerForce = SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius);
break;
case SB.Alignment:
steerForce = SteeringBehaviours.Alignment(ref allCars, this, ref currentPosition, ref velocity, max_speed);
break;
case SB.Separation:
steerForce = SteeringBehaviours.Separation(ref allCars, this, ref currentPosition, ref velocity, max_speed);
break;
case SB.CF:
steerForce = Vector2.Add(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), SteeringBehaviours.Flee(ref targetPosition, ref currentPosition, ref velocity, max_speed, FOV, vehicleNo));
break;
case SB.CA:
if (weightedSum)
{
steerForce += Vector2.Multiply(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), .2f);
steerForce += Vector2.Multiply(SteeringBehaviours.Alignment(ref allCars, this, ref currentPosition, ref velocity, max_speed), .1f);
}
else
{
steerForce = Vector2.Add(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), SteeringBehaviours.Alignment(ref allCars, this, ref currentPosition, ref velocity, max_speed));
}
break;
case SB.CAS:
if (weightedSum)
{
steerForce = Vector2.Add(SteeringBehaviours.Separation(ref allCars, this, ref currentPosition, ref velocity, max_speed), Vector2.Add(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), SteeringBehaviours.Alignment(ref allCars, this, ref currentPosition, ref velocity, max_speed)));
}
else
{
steerForce = Vector2.Multiply(SteeringBehaviours.Separation(ref allCars, this, ref currentPosition, ref velocity, max_speed), .3f);
steerForce += Vector2.Multiply(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), .2f);
steerForce += Vector2.Multiply(SteeringBehaviours.Alignment(ref allCars, this, ref currentPosition, ref velocity, max_speed), .5f);
}
break;
case SB.CS:
if (weightedSum)
{
steerForce = Vector2.Add(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), SteeringBehaviours.Separation(ref allCars, this, ref currentPosition, ref velocity, max_speed));
}
else
{
steerForce = Vector2.Multiply(SteeringBehaviours.Separation(ref allCars, this, ref currentPosition, ref velocity, max_speed), .8f);
steerForce += Vector2.Multiply(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), .2f);
}
break;
case SB.FCAS:
if (weightedSum)
{
steerForce = Vector2.Add(SteeringBehaviours.Alignment(ref allCars, this, ref currentPosition, ref velocity, max_speed), Vector2.Add(SteeringBehaviours.Separation(ref allCars, this, ref currentPosition, ref velocity, max_speed), Vector2.Add(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), SteeringBehaviours.Flee(ref targetPosition, ref currentPosition, ref velocity, max_speed, FOV, vehicleNo))));
}
else
{
steerForce = Vector2.Multiply(SteeringBehaviours.Flee(ref targetPosition, ref currentPosition, ref velocity, max_speed, FOV, vehicleNo), .4f);
steerForce += Vector2.Multiply(SteeringBehaviours.Separation(ref allCars, this, ref currentPosition, ref velocity, max_speed), .3f);
steerForce += Vector2.Multiply(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), .2f);
steerForce += Vector2.Multiply(SteeringBehaviours.Alignment(ref allCars, this, ref currentPosition, ref velocity, max_speed), .5f);
}
break;
case SB.FCS:
steerForce = Vector2.Add(SteeringBehaviours.Separation(ref allCars, this, ref currentPosition, ref velocity, max_speed), Vector2.Add(SteeringBehaviours.Cohesion(ref allCars, this, currentPosition, velocity, max_speed, CohesionRadius), SteeringBehaviours.Flee(ref targetPosition, ref currentPosition, ref velocity, max_speed, FOV, vehicleNo)));
break;
default:
break;
}
steerForce = VectorHelpers.Truncate(steerForce, max_force);
acceleration = steerForce / mass;
velocity = VectorHelpers.Truncate(velocity + acceleration, max_speed);
currentPosition = Vector2.Add(velocity, currentPosition);
var mirrored = true;
if (!mirrored)
{
if (currentPosition.X > clientSize.Width)
{
currentPosition.X = 0;
}
if (currentPosition.Y > clientSize.Height)
{
currentPosition.Y = 0;
}
if (currentPosition.X < 0)
{
currentPosition.X = clientSize.Width;
}
if (currentPosition.Y < 0)
{
currentPosition.Y = clientSize.Height;
}
}
else
{
if (currentPosition.X > clientSize.Width)
{
velocity.X *= -1;
}
if (currentPosition.Y > clientSize.Height)
{
velocity.Y *= -1;
}
if (currentPosition.X < 0)
{
velocity.X *= -1;
}
;
if (currentPosition.Y < 0)
{
velocity.Y *= -1;
}
;
}
currentPosition = new Vector2(MathHelper.Clamp(currentPosition.X, 0, clientSize.Width),
MathHelper.Clamp(currentPosition.Y, 0, clientSize.Height));
targetChanged = false;
}
