public SteeringBehaviours(Fighter entity)
{
this.fighter = entity;
calculationMethod = CalculationMethods.WeightedTruncatedRunningSumWithPrioritisation;
sphere = new Sphere(0.2f);
XNAGame.Instance().Children.Add(sphere);
wanderTarget = new Vector3(randomClamped(), randomClamped(), randomClamped());
wanderTarget.Normalize();
weights.Add(behaviour_type.allignment, 1.0f);
weights.Add(behaviour_type.cohesion, 2.0f);
weights.Add(behaviour_type.obstacle_avoidance, 20.0f);
weights.Add(behaviour_type.wall_avoidance, 20.0f);
weights.Add(behaviour_type.wander, 1.0f);
weights.Add(behaviour_type.seek, 1.0f);
weights.Add(behaviour_type.flee, 1.0f);
weights.Add(behaviour_type.arrive, 1.0f);
weights.Add(behaviour_type.pursuit, 1.0f);
weights.Add(behaviour_type.offset_pursuit, 1.0f);
weights.Add(behaviour_type.interpose, 1.0f);
weights.Add(behaviour_type.hide, 1.0f);
weights.Add(behaviour_type.evade, 0.01f);
weights.Add(behaviour_type.follow_path, 1.0f);
weights.Add(behaviour_type.separation, 1.0f);
}
Vector3 obstacleAvoidance()
{
Vector3 force = Vector3.Zero;
makeFeelers();
List<Sphere> tagged = new List<Sphere>();
float minBoxLength = 20.0f;
float boxLength = minBoxLength + ((fighter.velocity.Length()/fighter.maxSpeed) * minBoxLength * 2.0f);
if (float.IsNaN(boxLength))
{
System.Console.WriteLine("NAN");
}
// Matt Bucklands Obstacle avoidance
// First tag obstacles in range
foreach (Entity child in XNAGame.Instance().Children)
{
if (child is Obstacle)
{
Obstacle obstacle = (Obstacle)child;
Vector3 toCentre = fighter.pos - obstacle.pos;
float dist = toCentre.Length();
if (dist < boxLength)
{
tagged.Add(obstacle);
}
}
}
float distToClosestIP = float.MaxValue;
Sphere closestIntersectingObstacle = null;
Vector3 localPosOfClosestObstacle = Vector3.Zero;
Vector3 intersection = Vector3.Zero;
Matrix localTransform = Matrix.Invert(fighter.worldTransform);
foreach (Obstacle o in tagged)
{
Vector3 localPos = Vector3.Transform(o.pos, localTransform);
//Vector3 localPos = o.pos - fighter.pos;
// If the local position has a positive Z value then it must lay
// behind the agent. (in which case it can be ignored)
if (localPos.Z <=0)
{
// If the distance from the x axis to the object's position is less
// than its radius + half the width of the detection box then there
// is a potential intersection.
float expandedRadius = fighter.BoundingSphere.Radius + o.Radius;
if ((Math.Abs(localPos.Y) < expandedRadius) && (Math.Abs(localPos.X) < expandedRadius))
{
// Now to do a ray/sphere intersection test. The center of the
// Create a temp Entity to hold the sphere in local space
Sphere tempSphere = new Sphere(expandedRadius);
tempSphere.pos = localPos;
// Create a ray
Ray ray = new Ray();
ray.pos = new Vector3(0, 0, 0);
ray.look = fighter.basis;
// Find the point of intersection
if (tempSphere.closestRayIntersects(ray, Vector3.Zero, ref intersection) == false)
{
return Vector3.Zero;
}
// Now see if its the closest, there may be other intersecting spheres
float dist = intersection.Length();
if (dist < distToClosestIP)
{
dist = distToClosestIP;
closestIntersectingObstacle = o;
localPosOfClosestObstacle = localPos;
}
}
}
if (closestIntersectingObstacle != null)
{
// Now calculate the force
// Calculate Z Axis braking force
float multiplier = 200 * (1.0f + (boxLength - localPosOfClosestObstacle.Z) / boxLength);
//calculate the lateral force
float expandedRadius = fighter.BoundingSphere.Radius + o.Radius;
force.X = (expandedRadius - Math.Abs(localPosOfClosestObstacle.X)) * multiplier;
force.Y = (expandedRadius - -Math.Abs(localPosOfClosestObstacle.X)) * multiplier;
if (localPosOfClosestObstacle.X > 0)
{
force.X = -force.X;
}
if (localPosOfClosestObstacle.Y > 0)
{
force.Y = -force.Y;
}
/*if (fighter.pos.X < o.pos.X)
{
force.X = -force.X;
}
if (fighter.pos.Y < o.pos.Y)
{
force.Y = -force.Y;
}*/
Line.DrawLine(fighter.pos, fighter.pos + fighter.look * boxLength, Color.BlueViolet);
//apply a braking force proportional to the obstacle's distance from
//the vehicle.
const float brakingWeight = 40.0f;
force.Z = (closestIntersectingObstacle.Radius -
localPosOfClosestObstacle.Z) *
brakingWeight;
//finally, convert the steering vector from local to world space
force = Vector3.Transform(force, fighter.worldTransform);
}
}
fighter.DrawFeelers = false;
fighter.DrawAxis = false;
checkNaN(force);
return force;
}