public MovingEntity(Vector2D position,
double radius,
Vector2D velocity,
double max_speed,
Vector2D heading,
double mass,
Vector2D scale,
double turn_rate,
double max_force) : base(0, position, radius)
{
m_vHeading = heading;
m_vVelocity = velocity;
m_dMass = mass;
m_vSide = m_vHeading.Perp();
m_dMaxSpeed = max_speed;
m_dMaxTurnRate = turn_rate;
m_dMaxForce = max_force;
m_vScale = scale;
m_OldPos = new Vector2D();
m_vSmoothedHeading = new Vector2D();
m_intOldCellID = -1;
m_pSteering = new SteeringBehavior(this);
m_HeadingHistory = new List<Vector2D>(SteerParams.Instance.NumSamplesForSmoothing);
m_intNextHeadingSlot = 0;
}
public void CreateRandomPath(int NumWaypoints,
double MinX,
double MinY,
double MaxX,
double MaxY)
{
m_WayPoints.Clear();
double midX = (MaxX+MinX)/2.0;
double midY = (MaxY+MinY)/2.0;
double smaller = Math.Min(midX, midY);
double spacing = Utils.TwoPi / (double)NumWaypoints;
for (int i=0; i<NumWaypoints; ++i)
{
double RadialDist = Utils.RandInRange(smaller*0.2f, smaller);
Vector2D temp = new Vector2D(RadialDist, 0.0f);
Utils.Vec2DRotateAroundOrigin(temp, i * spacing);
temp.X += midX;
temp.Y += midY;
m_WayPoints.Add(temp);
}
m_curWaypoint = m_WayPoints.GetEnumerator();
m_curWaypoint.MoveNext(); // set the first item ready to go
}
public Wall2D(Vector2D A, Vector2D B)
{
m_vA = A;
m_vB = B;
m_vN = new Vector2D();
CalculateNormal();
}
public InvertedAABBox2D(Vector2D topLeft, Vector2D bottomRight)
{
m_vTopLeft = topLeft;
m_vBottomRight = bottomRight;
m_vCenter = (topLeft + bottomRight) * 0.5;
m_Rectangle = new Rectangle((int)m_vTopLeft.X, (int)m_vTopLeft.Y, (int)(m_vBottomRight.X - m_vTopLeft.X), (int)(m_vBottomRight.Y - m_vTopLeft.Y));
}
public BaseGameEntity()
{
m_ID = NextValidID();
m_dBoundingRadius=0.0;
m_vPos = new Vector2D();
m_vScale = new Vector2D(1.0,1.0);
m_EntityType = default_entity_type;
m_bTag = false;
}
//this can be used to create an entity with a 'forced' ID. It can be used
//when a previously created entity has been removed and deleted from the
//game for some reason. For example, The Raven map editor uses this ctor
//in its undo/redo operations.
//USE WITH CAUTION!
public BaseGameEntity(int entity_type, int ForcedID)
{
m_ID = ForcedID;
m_dBoundingRadius = 0.0;
m_vPos = new Vector2D();
m_vScale = new Vector2D(1.0, 1.0);
m_EntityType = entity_type;
m_bTag = false;
}
public BaseGameEntity(int entity_type, Vector2D pos, double r)
{
m_ID = NextValidID();
m_dBoundingRadius = r;
m_vPos = pos;
m_vScale = new Vector2D(1.0, 1.0);
m_EntityType = entity_type;
m_bTag = false;
}
//given a position in the game space this method determines the relevant cell's index
private int PositionToIndex(Vector2D pos)
{
int idx = (int)(m_iNumCellsX * pos.X / m_dSpaceWidth) +
((int)((m_iNumCellsY) * pos.Y / m_dSpaceHeight) * m_iNumCellsX);
//if the entity's position is equal to vector2d(m_dSpaceWidth, m_dSpaceHeight)
//then the index will overshoot. We need to check for this and adjust
if (idx > m_Cells.Count - 1) idx = m_Cells.Count - 1;
return idx;
}
private GameWorld()
{
m_bPaused = false;
m_bWrap = false;
m_blnSmoothing = true;
m_bCellSpaceOn = false;
m_dTimeElapsed = 0.0;
m_Walls = null;
m_pCellSpace = null;
m_Obstacles = null;
m_Agents = null;
m_cxClient = 0;
m_cyClient = 0;
m_vTargetPos = new Vector2D();
}
//applies a 2D transformation matrix to a single Vector2D
public void TransformVector2D(Vector2D vPoint)
{
double tempX = (m_Matrix._11 * vPoint.X) + (m_Matrix._21 * vPoint.Y) + (m_Matrix._31);
double tempY = (m_Matrix._12 * vPoint.X) + (m_Matrix._22 * vPoint.Y) + (m_Matrix._32);
vPoint.X = tempX;
vPoint.Y = tempY;
}
//--------------------------- Wander -------------------------------------
//
// This behavior makes the agent wander about randomly
//------------------------------------------------------------------------
public Vector2D Wander()
{
//this behavior is dependent on the update rate, so this line must
//be included when using time independent framerate.
double JitterThisTimeSlice = m_dWanderJitter * GameWorld.Instance.getTimeElapsed();
//first, add a small random vector to the target's position
m_vWanderTarget += new Vector2D(Utils.RandomClamped() * JitterThisTimeSlice,
Utils.RandomClamped() * JitterThisTimeSlice);
//reproject this new vector back on to a unit circle
m_vWanderTarget.Normalize();
//increase the length of the vector to the same as the radius
//of the wander circle
m_vWanderTarget *= m_dWanderRadius;
//move the target into a position WanderDist in front of the agent
Vector2D target = (m_vWanderTarget + new Vector2D(m_dWanderDistance, 0));
//project the target into world space
Vector2D Target = (Utils.PointToWorldSpace(target,
m_parentMovingEntity.Heading(),
m_parentMovingEntity.Side(),
m_parentMovingEntity.Pos));
//and steer towards it
return Target - m_parentMovingEntity.Pos;
}
//----------------------------- Flee -------------------------------------
//
// Does the opposite of Seek
//------------------------------------------------------------------------
public Vector2D Flee(Vector2D TargetPos)
{
//only flee if the target is within 'panic distance'. Work in distance
//squared space.
/* double PanicDistanceSq = 100.0f * 100.0;
if (Vec2DDistanceSq(m_parentMovingEntity.Pos, target) > PanicDistanceSq)
{
return Vector2D(0,0);
}
*/
Vector2D DesiredVelocity = Vector2D.Vec2DNormalize(m_parentMovingEntity.Pos - TargetPos)
* m_parentMovingEntity.MaxSpeed;
return (DesiredVelocity - m_parentMovingEntity.Velocity);
}
//---------------------- CalculateDithered ----------------------------
//
// this method sums up the active behaviors by assigning a probabilty
// of being calculated to each behavior. It then tests the first priority
// to see if it should be calcukated this simulation-step. If so, it
// calculates the steering force resulting from this behavior. If it is
// more than zero it returns the force. If zero, or if the behavior is
// skipped it continues onto the next priority, and so on.
//
// NOTE: Not all of the behaviors have been implemented in this method,
// just a few, so you get the general idea
//------------------------------------------------------------------------
public Vector2D CalculateDithered()
{
//reset the steering force
m_vSteeringForce.Zero();
if (On(behavior_type.wall_avoidance) && Utils.RandFloat() < SteerParams.Instance.PrWallAvoidance)
{
m_vSteeringForce = WallAvoidance(GameWorld.Instance.Walls) *
m_dWeightWallAvoidance / SteerParams.Instance.PrWallAvoidance;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
if (On(behavior_type.obstacle_avoidance) && Utils.RandFloat() < SteerParams.Instance.PrObstacleAvoidance)
{
m_vSteeringForce += ObstacleAvoidance(GameWorld.Instance.Obstacles) *
m_dWeightObstacleAvoidance / SteerParams.Instance.PrObstacleAvoidance;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
if (!GameWorld.Instance.SpacePartitioningOn)
{
if (On(behavior_type.separation) && Utils.RandFloat() < SteerParams.Instance.PrSeparation)
{
m_vSteeringForce += Separation(GameWorld.Instance.Agents) *
m_dWeightSeparation / SteerParams.Instance.PrSeparation;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
}
else
{
if (On(behavior_type.separation) && Utils.RandFloat() < SteerParams.Instance.PrSeparation)
{
m_vSteeringForce += SeparationPlus(GameWorld.Instance.Agents) *
m_dWeightSeparation / SteerParams.Instance.PrSeparation;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
}
if (On(behavior_type.flee) && Utils.RandFloat() < SteerParams.Instance.PrFlee)
{
Debug.Assert(!Vector2D.IsNull(GameWorld.Instance.TargetPos), "TargetPos not assigned");
m_vSteeringForce += Flee(GameWorld.Instance.TargetPos) * m_dWeightFlee / SteerParams.Instance.PrFlee;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
if (On(behavior_type.evade) && Utils.RandFloat() < SteerParams.Instance.PrEvade)
{
Debug.Assert(m_pTargetAgent1 != null, "Evade target not assigned");
m_vSteeringForce += Evade(m_pTargetAgent1) * m_dWeightEvade / SteerParams.Instance.PrEvade;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
if (!GameWorld.Instance.SpacePartitioningOn)
{
if (On(behavior_type.allignment) && Utils.RandFloat() < SteerParams.Instance.PrAlignment)
{
m_vSteeringForce += Alignment(GameWorld.Instance.Agents) *
m_dWeightAlignment / SteerParams.Instance.PrAlignment;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
if (On(behavior_type.cohesion) && Utils.RandFloat() < SteerParams.Instance.PrCohesion)
{
m_vSteeringForce += Cohesion(GameWorld.Instance.Agents) *
m_dWeightCohesion / SteerParams.Instance.PrCohesion;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
}
else
{
if (On(behavior_type.allignment) && Utils.RandFloat() < SteerParams.Instance.PrAlignment)
{
m_vSteeringForce += AlignmentPlus(GameWorld.Instance.Agents) *
m_dWeightAlignment / SteerParams.Instance.PrAlignment;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
if (On(behavior_type.cohesion) && Utils.RandFloat() < SteerParams.Instance.PrCohesion)
{
m_vSteeringForce += CohesionPlus(GameWorld.Instance.Agents) *
m_dWeightCohesion / SteerParams.Instance.PrCohesion;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
}
if (On(behavior_type.wander) && Utils.RandFloat() < SteerParams.Instance.PrWander)
{
m_vSteeringForce += Wander() * m_dWeightWander / SteerParams.Instance.PrWander;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
if (On(behavior_type.seek) && Utils.RandFloat() < SteerParams.Instance.PrSeek)
{
Debug.Assert(!Vector2D.IsNull(GameWorld.Instance.TargetPos), "TargetPos not assigned");
m_vSteeringForce += Seek(GameWorld.Instance.TargetPos) * m_dWeightSeek / SteerParams.Instance.PrSeek;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
if (On(behavior_type.arrive) && Utils.RandFloat() < SteerParams.Instance.PrArrive)
{
Debug.Assert(!Vector2D.IsNull(GameWorld.Instance.TargetPos), "TargetPos not assigned");
m_vSteeringForce += Arrive(GameWorld.Instance.TargetPos, (int)m_Deceleration) *
m_dWeightArrive / SteerParams.Instance.PrArrive;
if (!m_vSteeringForce.isZero())
{
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
}
return m_vSteeringForce;
}
//--------------------- AccumulateForce ----------------------------------
//
// This function calculates how much of its max steering force the
// vehicle has left to apply and then applies that amount of the
// force to add.
//------------------------------------------------------------------------
public bool AccumulateForce(ref Vector2D RunningTot, Vector2D ForceToAdd)
{
//calculate how much steering force the vehicle has used so far
double MagnitudeSoFar = RunningTot.Length();
//calculate how much steering force remains to be used by this vehicle
double MagnitudeRemaining = m_parentMovingEntity.MaxForce - MagnitudeSoFar;
//return false if there is no more force left to use
if (MagnitudeRemaining <= 0.0) return false;
//calculate the magnitude of the force we want to add
double MagnitudeToAdd = ForceToAdd.Length();
//if the magnitude of the sum of ForceToAdd and the running total
//does not exceed the maximum force available to this vehicle, just
//add together. Otherwise add as much of the ForceToAdd vector is
//possible without going over the max.
if (MagnitudeToAdd < MagnitudeRemaining)
{
RunningTot += ForceToAdd;
}
else
{
//add it to the steering force
RunningTot += (Vector2D.Vec2DNormalize(ForceToAdd) * MagnitudeRemaining);
}
return true;
}
//-------------------------------- Cohesion ------------------------------
//
// returns a steering force that attempts to move the agent towards the
// center of mass of the agents in its immediate area
//------------------------------------------------------------------------
public Vector2D Cohesion(List<MovingEntity> neighbors)
{
//first find the center of mass of all the agents
Vector2D CenterOfMass = new Vector2D(0.0, 0.0);
Vector2D SteeringForce = new Vector2D(0.0, 0.0);
int NeighborCount = 0;
//iterate through the neighbors and sum up all the position vectors
foreach (MovingEntity neighbor in neighbors)
{
//make sure *this* agent isn't included in the calculations and that
//the agent being examined is close enough ***also make sure it doesn't
//include the evade target ***
if ((neighbor != m_parentMovingEntity) && neighbor.IsTagged() &&
(neighbor != m_pTargetAgent1))
{
CenterOfMass += neighbor.Pos;
++NeighborCount;
}
}
if (NeighborCount > 0)
{
//the center of mass is the average of the sum of positions
CenterOfMass /= (double)NeighborCount;
//now seek towards that position
SteeringForce = Seek(CenterOfMass);
}
//the magnitude of cohesion is usually much larger than separation or
//allignment so it usually helps to normalize it.
return Vector2D.Vec2DNormalize(SteeringForce);
}
public void OffsetPursuitOn(MovingEntity v1, Vector2D offset) { m_iFlags |= (int)behavior_type.offset_pursuit; m_vOffset = offset; m_pTargetAgent1 = v1; }
//----------------------- Calculate --------------------------------------
//
// calculates the accumulated steering force according to the method set
// in m_SummingMethod
//------------------------------------------------------------------------
public Vector2D Calculate()
{
//reset the steering force
m_vSteeringForce.Zero();
//use space partitioning to calculate the neighbours of this vehicle
//if switched on. If not, use the standard tagging system
if (!GameWorld.Instance.SpacePartitioningOn)
{
//tag neighbors if any of the following 3 group behaviors are switched on
if (On(behavior_type.separation) || On(behavior_type.allignment) || On(behavior_type.cohesion))
{
GameWorld.Instance.TagAgentsWithinViewRange(m_parentMovingEntity, m_dViewDistance);
}
}
else
{
//calculate neighbours in cell-space if any of the following 3 group
//behaviors are switched on
if (On(behavior_type.separation) || On(behavior_type.allignment) || On(behavior_type.cohesion))
{
GameWorld.Instance.CellSpaces.CalculateNeighbors(m_parentMovingEntity.Pos, m_dViewDistance);
}
}
switch (m_SummingMethod)
{
case summing_method.weighted_average:
m_vSteeringForce = CalculateWeightedSum(); break;
case summing_method.prioritized:
m_vSteeringForce = CalculatePrioritized(); break;
case summing_method.dithered:
m_vSteeringForce = CalculateDithered(); break;
default:
m_vSteeringForce = new Vector2D(0, 0); break;
}//end switch
return m_vSteeringForce;
}
/* NOTE: the next three behaviors are the same as the above three, except
that they use a cell-space partition to find the neighbors
*/
//---------------------------- Separation --------------------------------
//
// this calculates a force repelling from the other neighbors
//
// USES SPACIAL PARTITIONING
//------------------------------------------------------------------------
public Vector2D SeparationPlus(List<MovingEntity> neighbors)
{
Vector2D SteeringForce = new Vector2D(0.0, 0.0);
//iterate through the neighbors and sum up all the position vectors
foreach (MovingEntity pV in GameWorld.Instance.CellSpaces.ListOfNeighbours())
{
//make sure this agent isn't included in the calculations and that
//the agent being examined is close enough
if (pV != m_parentMovingEntity)
{
Vector2D ToAgent = (m_parentMovingEntity.Pos - pV.Pos);
//scale the force inversely proportional to the agents distance
//from its neighbor.
SteeringForce += Vector2D.Vec2DNormalize(ToAgent) / ToAgent.Length();
}
}
return SteeringForce;
}
//---------------------- CalculateWeightedSum ----------------------------
//
// this simply sums up all the active behaviors X their weights and
// truncates the result to the max available steering force before
// returning
//------------------------------------------------------------------------
public Vector2D CalculateWeightedSum()
{
if (On(behavior_type.wall_avoidance))
{
m_vSteeringForce += WallAvoidance(GameWorld.Instance.Walls) * m_dWeightWallAvoidance;
}
if (On(behavior_type.obstacle_avoidance))
{
m_vSteeringForce += ObstacleAvoidance(GameWorld.Instance.Obstacles) * m_dWeightObstacleAvoidance;
}
if (On(behavior_type.evade))
{
Debug.Assert(m_pTargetAgent1 != null, "Evade target not assigned");
m_vSteeringForce += Evade(m_pTargetAgent1) * m_dWeightEvade;
}
//these next three can be combined for flocking behavior (wander is
//also a good behavior to add into this mix)
if (!GameWorld.Instance.SpacePartitioningOn)
{
if (On(behavior_type.separation))
{
m_vSteeringForce += Separation(GameWorld.Instance.Agents) * m_dWeightSeparation;
}
if (On(behavior_type.allignment))
{
m_vSteeringForce += Alignment(GameWorld.Instance.Agents) * m_dWeightAlignment;
}
if (On(behavior_type.cohesion))
{
m_vSteeringForce += Cohesion(GameWorld.Instance.Agents) * m_dWeightCohesion;
}
}
else
{
if (On(behavior_type.separation))
{
m_vSteeringForce += SeparationPlus(GameWorld.Instance.Agents) * m_dWeightSeparation;
}
if (On(behavior_type.allignment))
{
m_vSteeringForce += AlignmentPlus(GameWorld.Instance.Agents) * m_dWeightAlignment;
}
if (On(behavior_type.cohesion))
{
m_vSteeringForce += CohesionPlus(GameWorld.Instance.Agents) * m_dWeightCohesion;
}
}
if (On(behavior_type.wander))
{
m_vSteeringForce += Wander() * m_dWeightWander;
}
if (On(behavior_type.seek))
{
Debug.Assert(!Vector2D.IsNull(GameWorld.Instance.TargetPos), "TargetPos not assigned");
m_vSteeringForce += Seek(GameWorld.Instance.TargetPos) * m_dWeightSeek;
}
if (On(behavior_type.flee))
{
Debug.Assert(!Vector2D.IsNull(GameWorld.Instance.TargetPos), "TargetPos not assigned");
m_vSteeringForce += Flee(GameWorld.Instance.TargetPos) * m_dWeightFlee;
}
if (On(behavior_type.arrive))
{
Debug.Assert(!Vector2D.IsNull(GameWorld.Instance.TargetPos), "TargetPos not assigned");
m_vSteeringForce += Arrive(GameWorld.Instance.TargetPos, (int)m_Deceleration) * m_dWeightArrive;
}
if (On(behavior_type.pursuit))
{
Debug.Assert(m_pTargetAgent1 != null, "pursuit target not assigned");
m_vSteeringForce += Pursuit(m_pTargetAgent1) * m_dWeightPursuit;
}
if (On(behavior_type.offset_pursuit))
{
Debug.Assert(m_pTargetAgent1 != null, "pursuit target not assigned");
Debug.Assert(!Vector2D.IsNull(m_vOffset), "No offset assigned");
m_vSteeringForce += OffsetPursuit(m_pTargetAgent1, m_vOffset) * m_dWeightOffsetPursuit;
}
if (On(behavior_type.interpose))
{
Debug.Assert(m_pTargetAgent1 != null && m_pTargetAgent2 != null, "Interpose agents not assigned");
m_vSteeringForce += Interpose(m_pTargetAgent1, m_pTargetAgent2) * m_dWeightInterpose;
}
if (On(behavior_type.hide))
{
Debug.Assert(m_pTargetAgent1 != null, "Hide target not assigned");
m_vSteeringForce += Hide(m_pTargetAgent1, GameWorld.Instance.Obstacles) * m_dWeightHide;
}
if (On(behavior_type.follow_path))
{
m_vSteeringForce += FollowPath() * m_dWeightFollowPath;
}
m_vSteeringForce.Truncate(m_parentMovingEntity.MaxForce);
return m_vSteeringForce;
}
//---------------------------- Alignment ---------------------------------
//
// returns a force that attempts to align this agents heading with that
// of its neighbors
//
// USES SPACIAL PARTITIONING
//------------------------------------------------------------------------
public Vector2D AlignmentPlus(List<MovingEntity> neighbors)
{
//This will record the average heading of the neighbors
Vector2D AverageHeading = new Vector2D();
//This count the number of vehicles in the neighborhood
double NeighborCount = 0.0;
//iterate through the neighbors and sum up all the position vectors
foreach (MovingEntity pV in GameWorld.Instance.CellSpaces.ListOfNeighbours())
{
//make sure *this* agent isn't included in the calculations and that
//the agent being examined is close enough
if (pV != m_parentMovingEntity)
{
AverageHeading += pV.Heading();
++NeighborCount;
}
}
//if the neighborhood contained one or more vehicles, average their
//heading vectors.
if (NeighborCount > 0.0)
{
AverageHeading /= NeighborCount;
AverageHeading -= m_parentMovingEntity.Heading();
}
return AverageHeading;
}
/////////////////////////////////////////////////////////////////////////////// START OF BEHAVIORS
//------------------------------- Seek -----------------------------------
//
// Given a target, this behavior returns a steering force which will
// direct the agent towards the target
//------------------------------------------------------------------------
public Vector2D Seek(Vector2D TargetPos)
{
Vector2D DesiredVelocity = Vector2D.Vec2DNormalize(TargetPos - m_parentMovingEntity.Pos)
* m_parentMovingEntity.MaxSpeed;
return (DesiredVelocity - m_parentMovingEntity.Velocity);
}
//-------------------------------- Cohesion ------------------------------
//
// returns a steering force that attempts to move the agent towards the
// center of mass of the agents in its immediate area
//
// USES SPACIAL PARTITIONING
//------------------------------------------------------------------------
public Vector2D CohesionPlus(List<MovingEntity> neighbors)
{
//first find the center of mass of all the agents
Vector2D CenterOfMass = new Vector2D();
Vector2D SteeringForce = new Vector2D();
int NeighborCount = 0;
//iterate through the neighbors and sum up all the position vectors
foreach (MovingEntity pV in GameWorld.Instance.CellSpaces.ListOfNeighbours())
{
//make sure *this* agent isn't included in the calculations and that
//the agent being examined is close enough
if (pV != m_parentMovingEntity)
{
CenterOfMass += pV.Pos;
++NeighborCount;
}
}
if (NeighborCount > 0)
{
//the center of mass is the average of the sum of positions
CenterOfMass /= (double)NeighborCount;
//now seek towards that position
SteeringForce = Seek(CenterOfMass);
}
//the magnitude of cohesion is usually much larger than separation or
//allignment so it usually helps to normalize it.
return Vector2D.Vec2DNormalize(SteeringForce);
}
//--------------------------- Arrive -------------------------------------
//
// This behavior is similar to seek but it attempts to arrive at the
// target with a zero velocity
//------------------------------------------------------------------------
public Vector2D Arrive(Vector2D TargetPos, int decelerationStep)
{
Vector2D ToTarget = TargetPos - m_parentMovingEntity.Pos;
//calculate the distance to the target
double dist = ToTarget.Length();
if (dist > 0)
{
//because Deceleration is enumerated as an int, this value is required
//to provide fine tweaking of the deceleration..
double DecelerationTweaker = 0.3;
//calculate the speed required to reach the target given the desired
//deceleration
double speed = dist / ((double)decelerationStep * DecelerationTweaker);
//make sure the velocity does not exceed the max
speed = Math.Min(speed, m_parentMovingEntity.MaxSpeed);
//from here proceed just like Seek except we don't need to normalize
//the ToTarget vector because we have already gone to the trouble
//of calculating its length: dist.
Vector2D DesiredVelocity = (ToTarget * speed / dist);
return (DesiredVelocity - m_parentMovingEntity.Velocity);
}
return new Vector2D(0, 0);
}
//--------------------------- Hide ---------------------------------------
//
//------------------------------------------------------------------------
public Vector2D Hide(MovingEntity hunter, List<BaseGameEntity> obstacles)
{
double DistToClosest = Double.MaxValue;
Vector2D BestHidingSpot = new Vector2D(0.0, 0.0);
foreach (BaseGameEntity curOb in obstacles)
{
//calculate the position of the hiding spot for this obstacle
Vector2D HidingSpot = GetHidingPosition(curOb.Pos, curOb.BRadius, hunter.Pos);
//work in distance-squared space to find the closest hiding
//spot to the agent
double dist = Vector2D.Vec2DDistanceSq(HidingSpot, m_parentMovingEntity.Pos);
if (dist < DistToClosest)
{
DistToClosest = dist;
BestHidingSpot = HidingSpot;
}
}//end while
//if no suitable obstacles found then Evade the hunter
if (DistToClosest == Double.MaxValue)
{
return Evade(hunter);
}
//else use Arrive on the hiding spot
return Arrive(BestHidingSpot, (int)Deceleration.fast);
}
public Wall2D()
{
m_vN = new Vector2D();
}
//------------------------- GetHidingPosition ----------------------------
//
// Given the position of a hunter, and the position and radius of
// an obstacle, this method calculates a position DistanceFromBoundary
// away from its bounding radius and directly opposite the hunter
//------------------------------------------------------------------------
public Vector2D GetHidingPosition(Vector2D posOb, double radiusOb, Vector2D posHunter)
{
//calculate how far away the agent is to be from the chosen obstacle's
//bounding radius
double DistanceFromBoundary = 30.0;
double DistAway = radiusOb + DistanceFromBoundary;
//calculate the heading toward the object from the hunter
Vector2D ToOb = Vector2D.Vec2DNormalize(posOb - posHunter);
//scale it to size and add to the obstacles position to get
//the hiding spot.
return (ToOb * DistAway) + posOb;
}
public Wall2D(Vector2D A, Vector2D B, Vector2D N)
{
m_vA = A;
m_vB = B;
m_vN = N;
}
//------------------------- Offset Pursuit -------------------------------
//
// Produces a steering force that keeps a vehicle at a specified offset
// from a leader vehicle
//------------------------------------------------------------------------
public Vector2D OffsetPursuit(MovingEntity leader, Vector2D offset)
{
//calculate the offset's position in world space
Vector2D WorldOffsetPos = Utils.PointToWorldSpace(offset,
leader.Heading(),
leader.Side(),
leader.Pos);
Vector2D ToOffset = WorldOffsetPos - m_parentMovingEntity.Pos;
//the lookahead time is propotional to the distance between the leader
//and the pursuer; and is inversely proportional to the sum of both
//agent's velocities
double LookAheadTime = ToOffset.Length() /
(m_parentMovingEntity.MaxSpeed + leader.Speed());
//now Arrive at the predicted future position of the offset
return Arrive(WorldOffsetPos + leader.Velocity * LookAheadTime, (int)Deceleration.fast);
}
//create a rotation matrix from a 2D vector
public void Rotate(Vector2D fwd, Vector2D side)
{
Matrix mat = new Matrix();
mat._11 = fwd.X;
mat._12 = fwd.Y;
mat._13 = 0;
mat._21 = side.X;
mat._22 = side.Y;
mat._23 = 0;
mat._31 = 0;
mat._32 = 0;
mat._33 = 1;
//and multiply
MatrixMultiply(mat);
}
public void SetOffset(Vector2D offset) { m_vOffset = offset; }
