/// <summary>
/// Atack steering behavior
/// </summary>
/// <param name="caller">Game object which calles atack SB</param>
/// <param name="target">Target of the attack</param>
/// <returns>Force acting on caller</returns>
public static Vector3 Attack(Fighter caller, AlienCraft target, List<Fighter> friends)
{
float minimalDistanceToTargetSquared = 5.0f * 5.0f;
float shootingDistanceSquared = 15.0f * 15.0f;
float maximalDistaneToTargetSquared = 30.0f * 30.0f;
// if you're not escaping
if (!caller.IsEscaping)
{
Vector3 seekingForce = SeekWithSeparation(caller, target.Position, friends);
Vector3 separationForce = Vector3.Zero;
// if you're to close start escaping
if (Vector3.DistanceSquared(caller.Position, target.Position) < minimalDistanceToTargetSquared)
{
caller.IsEscaping = true;
}
// if you're in the shooting range slow down to minimum
if (Vector3.DistanceSquared(caller.Position, target.Position) < shootingDistanceSquared)
{
caller.Velocity = Vector3.Zero;
}
return seekingForce + separationForce;
}
// if you're escaping
else
{
// if you're far enough start shooting once again
if (Vector3.DistanceSquared(caller.Position, target.Position) > maximalDistaneToTargetSquared)
{
caller.IsEscaping = false;
}
return Flee(caller, target.Position);
}
}
public MainScene(WarGame game)
: base(game)
{
// creating post render target with 24-bit depth
PresentationParameters pp = game.Graphics.GraphicsDevice.PresentationParameters;
postTarget = new RenderTarget2D(game.Graphics.GraphicsDevice, pp.BackBufferWidth, pp.BackBufferHeight, false, game.Graphics.GraphicsDevice.DisplayMode.Format, DepthFormat.Depth24);
// creating objects used by environment shader
alienBaseEnvironmentRenTarget = new RenderTargetCube(game.Graphics.GraphicsDevice, 256, false, game.Graphics.GraphicsDevice.DisplayMode.Format, DepthFormat.Depth24);
alienBaseEnvironmentTextureCube = new TextureCube(game.Graphics.GraphicsDevice, 256, false, game.Graphics.GraphicsDevice.DisplayMode.Format);
// creating selection rectangle and adding it to the Scene
SelectionRectangle = new SelectionRectangle(game, this);
SceneComponents.Add(SelectionRectangle);
// the game is initially not in the debug mode
IsInDebugMode = false;
// adding ground element to the Scene
groundElement = new GroundElement(game, new Vector3(0, groundYAxisPosition, 0), this);
SceneComponents.Add(groundElement);
sceneObjects.Add(groundElement);
// setting the position of the alien base
alienBasePosition = new Vector3(170, groundYAxisPosition, 170);
//adding alien's base to the Scene
AlienBase = new AlienBuilding(game, alienBasePosition, this);
SceneComponents.Add(AlienBase);
sceneObjects.Add(AlienBase);
// adding alien crafts to the Scene
for (int i = 0; i < numberOfAliens; i++)
{
AlienCraft a;
// placing new craft in the first random and free place
do
{
Vector3 randomPosition = new Vector3(AlienBase.Position.X + (float)WarGame.RandomGenerator.NextDouble() * 50.0f - 25.0f,
GroundYAxisPosition + 1.0f,
AlienBase.Position.Z + (float)WarGame.RandomGenerator.NextDouble() * 50.0f - 25.0f);
a = new AlienCraft(game, this, randomPosition);
}
while (a.CheckForCollisions() != null);
SceneComponents.Add(a);
sceneObjects.Add(a);
alienCrafts.Add(a);
}
// adding skybox to the Scene
SceneComponents.Add(new Skybox(game));
}
/// <summary>
/// Wander steering behavior
/// </summary>
/// <param name="caller">Game object which calls the wander SB</param>
/// <returns>Force acting at the caller</returns>
public static Vector3 Wander(AlienCraft caller, List<AlienCraft> friends)
{
float wanderR = 2.0f;
float wanderD = 4.0f;
caller.WanderChange += (float)WarGame.RandomGenerator.NextDouble() - 0.5f;
Vector3 circleloc = caller.Velocity;
if (circleloc.LengthSquared() > 0)
circleloc.Normalize();
circleloc *= wanderD;
circleloc += caller.Position;
Vector2 circleOffSet = new Vector2(wanderR * (float)Math.Cos(caller.WanderChange), wanderR * (float)Math.Sin(caller.WanderChange));
Vector3 target = new Vector3(circleloc.X + circleOffSet.X, circleloc.Y, circleloc.Z + circleOffSet.Y);
caller.Target = target;
Vector3 seekForce = Seek(caller, caller.Target);
return seekForce + 2 * Separation(caller, friends);
}
/// <summary>
/// Wander ready to attack steering behaviour
/// </summary>
/// <param name="caller">GameObject which calls the ready to attack SB</param>
/// <param name="objects">List of fighters to attack</param>
/// <returns>Force acting on the game object</returns>
public static Vector3 WanderReadyToAttack(AlienCraft caller, List<AlienCraft> friends, List<Fighter> targets)
{
int FOV = 50;
Fighter fighterToSeek = null;
float minDistance = float.MaxValue;
foreach (Fighter f in targets)
{
float d = (caller.Position - f.Position).Length();
if (d < FOV)
if (d < minDistance)
{
minDistance = d;
fighterToSeek = f;
}
}
if (fighterToSeek == null)
return Wander(caller, friends);
else
return SeekWithSeparation(caller, fighterToSeek.Position, friends);
}
/// <summary>
/// Seek steering behavior combined with the separation
/// </summary>
/// <param name="caller">Game object which calls this SB</param>
/// <param name="target">Target seeked by the caller</param>
/// <param name="objects">List of fighters to separate from</param>
/// <returns>Force acting at the caller</returns>
public static Vector3 SeekWithSeparation(AlienCraft caller, Vector3 target, List<AlienCraft> objects)
{
if ((caller.Position - target).Length() > 5)
return Seek(caller, target) + 2 * Separation(caller, objects);
else if (Separation(caller, objects).Length() < 0.1f)
return Vector3.Zero;
else
return Seek(caller, target) + 6 * Separation(caller, objects);
}