/// <summary>
/// Checks if a particular dodge is valid
/// </summary>
private bool isDodgeValid(DynamicObject callingAI,float dodgeAngle,int dodgeAngleMultiplierYaw,int dodgeAngleMultiplierPitch,PathInformation pathInfo, StaticObject closestObstruction,float dodgeDistance, ref Vector3 dodgeWp)
{
bool bFlag = false;
//Define a conal area around the current path to choose another path from
Quaternion qRot = Quaternion.CreateFromYawPitchRoll(dodgeAngle * dodgeAngleMultiplierYaw, dodgeAngle * dodgeAngleMultiplierPitch, 0);
Vector3 choiceVector = Vector3.Normalize(
Vector3.Transform(pathInfo.currentWaypoint.Position - callingAI.Position,
Matrix.CreateFromQuaternion(qRot)));
dodgeWp = callingAI.Position + choiceVector * dodgeDistance;
if ((dodgeWp - closestObstruction.Position).Length() > dodgeDistance)
{
foreach (GridObjectInterface o in spatialGrid.checkNeighbouringBlocks(dodgeWp))
{
if (o != callingAI)
{
if (o is StaticObject)
{
if ((o.Position - dodgeWp).Length() > (o.getBoundingSphere().Radius + callingAI.getBoundingSphere().Radius * (DODGE_DISTANCE_MULTIPLIER)))
bFlag = true;
}
if (o is DynamicObject)
{
if (isObjectRegistered(o as DynamicObject))
{
Node otherObjectsWaypoint = objectPaths[o as DynamicObject].currentWaypoint;
if (otherObjectsWaypoint != null)
{
if ((otherObjectsWaypoint.Position - dodgeWp).Length() < (o.getBoundingSphere().Radius + callingAI.getBoundingSphere().Radius * (DODGE_DISTANCE_MULTIPLIER)))
bFlag = false;
}
}
}
if (!spatialGrid.isInGrid(new Node(dodgeWp,-1)))
bFlag = false;
}
}
}
return bFlag;
}
/// <summary>
/// Checks if there are any obstructions in close proximity which must be dodged
/// </summary>
/// <param name="AIObject">ai object to check around</param>
/// <returns>list of possible obstructions</returns>
private List<StaticObject> obstructionsInCloseProximity(DynamicObject AIObject)
{
List<StaticObject> results = new List<StaticObject>();
foreach (GridObjectInterface obj in this.spatialGrid.checkNeighbouringBlocks(AIObject))
{
if (obj is StaticObject && !(obj is Bullet || obj is Missile))
{
float radiusToCheck = (obj.getBoundingSphere().Radius + AIObject.getBoundingSphere().Radius) * DODGE_DISTANCE_MULTIPLIER;
if ((AIObject.Position - obj.Position).Length() <= radiusToCheck)
{
results.Add(obj as StaticObject);
}
}
}
return results;
}
/// <summary>
/// Method to test if a collision will occur on the current route of the calling ai (and which collision will occur first). If such
/// a possible collision is detected the callingAI will attempt to dodge the object.
/// </summary>
/// <param name="callingAI">AI that the test is performed for.</param>
/// <param name="obstructionsList">A list of obstructions as returned by PathIntersectTest</param>
private void avoidCollisions(DynamicObject callingAI, List<StaticObject> obstructionsList)
{
//find the closest obstruction and dodge it:
if (obstructionsList.Count == 0) return;
PathInformation pathInfo = objectPaths[callingAI];
StaticObject closestObstruction = obstructionsList.First();
float closestObstructionDistance = (closestObstruction.Position - callingAI.Position).Length();
for (int i = 1; i < obstructionsList.Count; ++i)
{
StaticObject obstruction = obstructionsList.ElementAt(i);
float distanceToObstruction = (obstruction.Position - callingAI.Position).Length();
if (distanceToObstruction < closestObstructionDistance)
{
closestObstruction = obstruction;
closestObstructionDistance = distanceToObstruction;
}
}
if (closestObstruction is DynamicObject)
if (isObjectRegistered(closestObstruction as DynamicObject))
if (objectPaths[closestObstruction as DynamicObject].currentWaypoint != null)
if (objectPaths[closestObstruction as DynamicObject].currentWaypoint.connectedEdges.Count == 0 || closestObstruction is playerObject)
return; // that object is dodging already don't make it stop
//Make the obstruction yield for the next few steps:
if (closestObstruction is DynamicObject)
if (!movementYieldList.Keys.Contains(closestObstruction as DynamicObject))
movementYieldList.Add(closestObstruction as DynamicObject, YIELD_TICKS);
//Now dodge it:
dodgeObject(callingAI, closestObstruction);
}
/// <summary>
/// Method to set the path of an ai unit in order to dodge an object
/// </summary>
/// <param name="callingAI">ai to perform dodge</param>
/// <param name="closestObstruction">closest obstruction</param>
private void dodgeObject(DynamicObject callingAI, StaticObject closestObstruction)
{
if (!this.isObjectRegistered(callingAI)) return;
PathInformation pathInfo = objectPaths[callingAI];
if (pathInfo.currentWaypoint == null) return;
if (!dodgeInactiveCountDown.Keys.Contains(callingAI))
dodgeInactiveCountDown.Add(callingAI, RETAIN_DODGE_PATH_TICKS);
else
return;
Vector3 dodgeWp = new Vector3();
bool bFlag = false;
// Set the new path:
float dodgeDistance = (callingAI.getBoundingSphere().Radius + closestObstruction.getBoundingSphere().Radius) * DODGE_DISTANCE_MULTIPLIER;
float distanceToObject = (callingAI.Position - closestObstruction.Position).Length();
float distanceToCurrentWp = (callingAI.Position - pathInfo.currentWaypoint.Position).Length();
float dodgeAngle = (float)Math.Abs(Math.Atan2(distanceToObject, dodgeDistance));
for (int i = (int)Math.Ceiling(dodgeAngle); i * dodgeAngle < Math.PI; ++i)
{
for (int j = (int)Math.Ceiling(dodgeAngle); j * dodgeAngle < Math.PI; ++j)
{
if (isDodgeValid(callingAI, dodgeAngle, i, j, pathInfo, closestObstruction, dodgeDistance, ref dodgeWp))
{
bFlag = true;
break;
}
if (isDodgeValid(callingAI, -dodgeAngle, i, j, pathInfo, closestObstruction, dodgeDistance, ref dodgeWp))
{
bFlag = true;
break;
}
}
if (bFlag)
break;
}
List<Node> path = pathInfo.remainingPath;
if (path.Count > 0)
path.Remove(path.Last());
path.Add(new Node(dodgeWp, -1));
pathInfo.remainingPath = path;
}
/// <summary>
/// Sets a new path for an object if it is already registered
/// </summary>
/// <param name="AIObject">Any registered dynamic object</param>
/// <param name="start">Start node (should be close to the object if possible)</param>
/// <param name="end">End node</param>
public void setNewPathForRegisteredObject(DynamicObject AIObject, Node start, Node end)
{
if (objectPaths.Keys.Contains(AIObject))
{
List<Node> path = AStar(start, end, AIObject is Destroyer);
if (path != null)
objectPaths[AIObject].remainingPath = path;
else //we just go the the start node
{
path = new List<Node>();
path.Add(start);
objectPaths[AIObject].remainingPath = path;
}
}
}
/// <summary>
/// Turns the ai to face towards the a waypoint
/// </summary>
/// <param name="vWantDir"></param>
/// <param name="vLookDir"></param>
/// <param name="objectToTurn"></param>
/// <param name="currentWaypoint"></param>
/// <param name="gt"></param>
internal void turnAI(ref Vector3 vWantDir, ref Vector3 vLookDir, DynamicObject objectToTurn, Vector3 currentWaypoint, GameTime gt)
{
//Calculate yaw and pitch for view direction and target direction
vWantDir = Vector3.Normalize(currentWaypoint - objectToTurn.Position);
vLookDir = Vector3.Normalize(-Matrix.CreateFromQuaternion(objectToTurn.rotation).Forward);
float distance = (float)Math.Sqrt(vWantDir.Z * vWantDir.Z + vWantDir.X * vWantDir.X);
float tpitch = distance == 0 ? (float)Math.Sign(-vWantDir.Y) * (float)Math.PI / 2 : -(float)Math.Atan2(vWantDir.Y, distance);
float tyaw = (float)Math.Atan2(vWantDir.X, vWantDir.Z);
distance = (float)Math.Sqrt(vLookDir.Z * vLookDir.Z + vLookDir.X * vLookDir.X);
float cyaw = (float)Math.Atan2(vLookDir.X, vLookDir.Z);
float cpitch = distance == 0 ? (float)Math.Sign(-vLookDir.Y) * (float)Math.PI / 2 : -(float)Math.Atan2(vLookDir.Y, distance);
//now rotate towards the target yaw and pitch
float diffy = tyaw - cyaw;
float diffp = tpitch - cpitch;
//get the direction we need to rotate in:
if (Math.Abs(diffy) > Math.PI)
if (tyaw > cyaw)
diffy = -(float)(Math.PI * 2 - Math.Abs(diffy));
else
diffy = (float)(Math.PI * 2 - Math.Abs(diffy));
if (Math.Abs(diffp) > Math.PI)
if (tpitch > cpitch)
diffp = -(float)(Math.PI * 2 - Math.Abs(diffp));
else
diffp = (float)(Math.PI * 2 - Math.Abs(diffp));
if (Math.Abs(diffp) > Math.Abs(objectToTurn.getpitchSpeed) * (float)(gt.ElapsedGameTime.TotalSeconds))
diffp = Math.Sign(diffp) * Math.Abs(objectToTurn.getpitchSpeed) * (float)(gt.ElapsedGameTime.TotalSeconds);
if (Math.Abs(diffy) > Math.Abs(objectToTurn.getYawSpeed) * (float)(gt.ElapsedGameTime.TotalSeconds))
diffy = Math.Sign(diffy) * Math.Abs(objectToTurn.getYawSpeed) * (float)(gt.ElapsedGameTime.TotalSeconds);
//special case: deal with the pitch if its PI/2 or -PI/2, because if its slightly off it causes problems:
if (Math.Abs(Math.Abs(tpitch) - Math.PI / 2) <= EPSILON_DISTANCE && !(Math.Abs(diffy) <= EPSILON_DISTANCE))
objectToTurn.rotation = Quaternion.CreateFromYawPitchRoll(tyaw, tpitch, 0);
else
objectToTurn.rotation = Quaternion.CreateFromYawPitchRoll(cyaw + diffy, cpitch + diffp, 0);
}
/// <summary>
/// Method to register an object for computer-based navigation
/// </summary>
/// <param name="AIObject">Any dynamic object capable of moving</param>
public void registerObject(DynamicObject AIObject)
{
if (!objectPaths.Keys.Contains(AIObject))
objectPaths.Add(AIObject, new PathInformation());
}
/// <summary>
/// Checks if an object is registered in the navigation computer
/// </summary>
/// <param name="AIObject">Object to check</param>
/// <returns>true iff object is registered</returns>
public bool isObjectRegistered(DynamicObject AIObject)
{
return objectPaths.Keys.Contains(AIObject);
}
/// <summary>
/// Method to get the current Path of a registered object
/// </summary>
/// <param name="o">registered object</param>
/// <returns>path if it exists. Either an empty list or Null otherwise</returns>
public List<Node> getPath(DynamicObject o)
{
return objectPaths[o].remainingPath;
}
/// <summary>
/// Performs a dogfight move against the opponent
/// </summary>
/// <param name="ti">Team on which the ai is registered</param>
/// <param name="ai">Character to perform move</param>
/// <param name="target">Opponent of the ai</param>
public void doDogfightMove(TeamInformation ti, DynamicObject ai, StaticObject target)
{
if (!this.isObjectRegistered(ai)) return;
float radiusToGoBehindTarget = (target.getBoundingSphere().Radius + ai.getBoundingSphere().Radius) * RADIUS_MULTIPLIER_TO_GO_BEHIND_TARGET;
Vector3 wpPosition = target.Position + Vector3.Normalize(Matrix.CreateFromQuaternion(target.rotation).Forward) * radiusToGoBehindTarget;
Vector3 wpDPosition = target.Position + Vector3.Normalize(Matrix.CreateFromQuaternion(target.rotation).Up) * radiusToGoBehindTarget / RADIUS_FACTOR_TO_GO_ABOVE_TARGET;
if (Vector3.Dot(Vector3.Normalize(wpPosition - target.Position), Vector3.Normalize(ai.Position - target.Position)) < DOT_ANGLE_TO_STOP_DOGFIGHT_MOVE ||
(ai.Position - target.Position).Length() > CHASE_WHEN_FURTHER)
{
PathInformation fighterPath = objectPaths[ai];
List<Node> waypointList = fighterPath.remainingPath;
//we clear the waypoint list and add new waypoints:
if (waypointList.Count > 0)
{
bool shouldAddTopWaypt = (Vector3.Dot(Vector3.Normalize(Matrix.CreateFromQuaternion(target.rotation).Forward), Vector3.Normalize(target.Position - ai.Position)) > 0);
if ((wpPosition - waypointList.ElementAt(0).Position).Length() > TARGET_WP_BUFFER || shouldAddTopWaypt)
{
waypointList.Clear();
if (shouldAddTopWaypt)
waypointList.Insert(0, new Node(wpDPosition, -1));
waypointList.Insert(0, new Node(wpPosition, -1));
}
}
else
{
if (Vector3.Dot(Vector3.Normalize(Matrix.CreateFromQuaternion(target.rotation).Forward), Vector3.Normalize(target.Position - ai.Position)) > 0)
waypointList.Insert(0, new Node(wpDPosition, -1));
waypointList.Insert(0, new Node(wpPosition, -1));
}
fighterPath.remainingPath = waypointList;
}
else //stop navigation (we are behind the target so we can start shooting it)
getPath(ai).Clear();
}
/// <summary>
/// Method to deregister an object in order to stop computer-based navigation for that object
/// </summary>
/// <param name="AIObject">Currently registered dynamic object</param>
public void deregisterObject(DynamicObject AIObject)
{
if (objectPaths.Keys.Contains(AIObject))
objectPaths.Remove(AIObject);
}