//Helper method to validate the spaceships movement, returns true if movement is valid, false if not
private bool ValidateMovement(Vector3 futurePosition, BoundingSphere planetBoundingSphere, Turret[] turrets)
{
BoundingSphere futureBoundingSphere = BoundingSphere;
futureBoundingSphere.Center = futurePosition;
//Check for collision with planet
if (futureBoundingSphere.Intersects(planetBoundingSphere))
{
return false;
}
//Loop through turrets and check for collisions
for (int i = 0; i < turrets.Length; i++)
{
if (futureBoundingSphere.Intersects(turrets[i].BoundingSphere))
return false;
}
return true;
}
/// <summary>
/// The update method where the logic for the movement of the spaceship is calculated.
/// </summary>
/// <param name="keyboardState">The current state of the keyboard</param>
/// <param name="planetBoundingSphere">The bounding sphere of the planet</param>
/// <param name="turrets">The array of turrets in the game</param>
public void Update(KeyboardState keyboardState, BoundingSphere planetBoundingSphere, Turret[] turrets)
{
Vector3 futurePosition; //The position the spaceship will move into at this gamestep, unless a collision will stop it
float turnAmountSide = 0;
float turnAmountUp = 0;
//Check if any keys are pressed down, if any are, add or subtract from that turn variable
if (keyboardState.IsKeyDown(Keys.A))
{
turnAmountSide = 0.03f;
}
else if (keyboardState.IsKeyDown(Keys.D))
{
turnAmountSide = -0.03f;
}
if (keyboardState.IsKeyDown(Keys.S))
{
turnAmountUp = 0.03f;
}
else if (keyboardState.IsKeyDown(Keys.W))
{
turnAmountUp = -0.03f;
}
//Calculate the rotation quaternion by creating angles from the turn amount values.
//Code from: http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series2/Flight_kinematics.php
Quaternion additionalRot = Quaternion.CreateFromAxisAngle(new Vector3(0, 1, 0), turnAmountSide) * Quaternion.CreateFromAxisAngle(new Vector3(1, 0, 0), turnAmountUp);
Rotation *= additionalRot;
//Calculate the position from the rotation
Vector3 addVector = Vector3.Transform(new Vector3(0, 0, -1), Rotation);
futurePosition = Position + addVector * GameConstants.ShipVelocity;
//Validate the spaceship's movement (only move it if the future position won't intersect the bounding sphere of the plabet or a turret)
//If it can move to the future position, update the current position, and update the bounding sphere to the new position
if (ValidateMovement(futurePosition, planetBoundingSphere, turrets))
{
Position = futurePosition;
IsCrashing = false;
BoundingSphere updatedSphere;
updatedSphere = BoundingSphere;
updatedSphere.Center = Position;
BoundingSphere = new BoundingSphere(updatedSphere.Center, updatedSphere.Radius);
}
else
{
IsCrashing = true;
}
}
/*
* Helper method for finding a random turret out of the turrets that are closest to the ship.
* Used when calculating which turret to fire a missile from
*/
private Turret closestTurretToShip()
{
//Work out how closest turrets to use to pick a random turret from
//This is worked out to be 20% of the total turrets, and at least 1
int numFiringTurrets = numTurrets / 5;
if (numFiringTurrets > 10)
{
numFiringTurrets = 1;
}
//Create an array for the current closest turrets, and a corrosponding array to
//hold their distances from the spaceship, for example, the distance from the spaceship
//of a turret at index 3 in the first array will be held in index 3 of the second array
Turret[] closestTurrets = new Turret[numFiringTurrets];
float[] closestTurretDistances = new float[numFiringTurrets];
//Initialise the arrays with dummy initial values
for (int i = 0; i < numFiringTurrets; i++)
{
closestTurrets[i] = new Turret();
closestTurretDistances[i] = float.MaxValue; //High number, so turrets will always replace these
}
//Iterate through each turret, checking if it is closer to the spaceship
//than any turrets in the current array of closest turrets
for (int i = 1; i < turrets.Length; i++)
{
float distance = Vector3.Distance(spaceship.Position, turrets[i].Position);
bool finished = false;
int j = 0;
while (!finished && j < numFiringTurrets)
{
//If is is closer
if (distance < closestTurretDistances[j])
{
//swap it in at the same index of the turret it was closer than
closestTurrets[j] = turrets[i];
closestTurretDistances[j] = distance;
finished = true; //Stop iterating
}
j++;
}
//Sort and reverse the array, so the furthest turrets will always be considered first
Array.Sort(closestTurretDistances, closestTurrets);
Array.Reverse(closestTurretDistances);
Array.Reverse(closestTurrets);
}
//Randomly pick a turret from the array of closests turrets, and return it
int turretToPickIndex = random.Next(0, numFiringTurrets);
return closestTurrets[turretToPickIndex];
}
/*
* Resests the game objects and some variables to the starting configurations.
* Much of this is very similar to the LoadContent method.
*/
private void ResetGame()
{
//Settings to reset to start a new game
retrievedFuelCells = 0;
menuScreenCounter = 0;
stepCounter = 0;
playerHealth = GameConstants.PlayerStartHealth;
//Create new fuelcells, turrets and missiles
fuelCells = new FuelCell[numFuelCells];
turrets = new Turret[numTurrets];
readyMissiles = new List<Missile>();
firedMissiles = new List<Missile>();
//Load the fuelcells, turrets and missiles in the same way they were loaded in LoadContent
for (int i = 0; i < numFuelCells; i++)
{
Vector3 axis = new Vector3((float)(random.NextDouble() - 0.5), (float)(random.NextDouble() - 0.5), (float)(random.NextDouble() - 0.5));
float angle = (float)random.NextDouble() * 6.242f;
fuelCells[i] = new FuelCell();
fuelCells[i].LoadContent(Content, "Models/fuelcell", axis, angle, planet.BoundingSphere);
}
for (int i = 0; i < numTurrets; i++)
{
Vector3 axis = new Vector3((float)(random.NextDouble() - 0.5), (float)(random.NextDouble() - 0.5), (float)(random.NextDouble() - 0.5));
float angle = (float)random.NextDouble() * 6.242f;
turrets[i] = new Turret();
turrets[i].LoadContent(Content, "Models/turret", axis, angle, planet.BoundingSphere);
}
for (int i = 0; i < GameConstants.NumMissiles; i++)
{
readyMissiles.Add(new Missile());
readyMissiles[i].LoadContent(Content, "Models/missile", spaceship);
}
explosions.Clear(); //Remove all occuring explosions
//Initial spaceship starting location and rotation
spaceship.Position = new Vector3(0, 300, 1000);
spaceship.Rotation = Quaternion.Identity;
exhaustParticleEmitter = new ParticleEmitter(fireParticles, 1000, spaceship.Position);
}
/// <summary>
/// Load all game objects with their models, as well ad initialising sounds and other
/// entities used in the game. Sets up spaceship starting location.
/// </summary>
protected override void LoadContent()
{
//Create a new SpriteBatch, which can be used to draw 2D graphics.
spriteBatch = new SpriteBatch(GraphicsDevice);
//Create a graphics device variable
device = graphics.GraphicsDevice;
//Load content of misc game entities
statsFont = Content.Load<SpriteFont>("Fonts/stats_font");
skyboxEffect = Content.Load<Effect>("Effects/skybox_effect");
splashScreenTexture = Content.Load<Texture2D> ("Images/splash_screen");
//Load object models
spaceship.LoadContent(Content, "Models/spaceship");
planet.LoadContent(Content, "Models/planet");
boundingSphere.Model = Content.Load<Model>("Models/sphere");
skyboxModel = LoadSkyboxModel("Models/skybox", out skyboxTextures);
//Iteratively load content for fuelcells, also generate the random seeds which will be used in calculating positions and rotation
for (int i = 0; i < numFuelCells; i++)
{
Vector3 axis = new Vector3((float)(random.NextDouble() - 0.5), (float)(random.NextDouble() - 0.5), (float)(random.NextDouble() - 0.5));
float angle = (float)random.NextDouble() * 6.242f;
fuelCells[i] = new FuelCell();
fuelCells[i].LoadContent(Content, "Models/fuelcell", axis, angle, planet.BoundingSphere);
}
//turrets loaded in the same was as fuelcells
for (int i = 0; i < numTurrets; i++)
{
Vector3 axis = new Vector3((float)(random.NextDouble() - 0.5), (float)(random.NextDouble() - 0.5), (float)(random.NextDouble() - 0.5));
float angle = (float)random.NextDouble() * 6.242f;
turrets[i] = new Turret();
turrets[i].LoadContent(Content, "Models/turret", axis, angle, planet.BoundingSphere);
}
//Populate the ready missile array with all the missiles
for (int i = 0; i < GameConstants.NumMissiles; i++)
{
readyMissiles.Add(new Missile());
readyMissiles[i].LoadContent(Content, "Models/missile", spaceship);
}
//Load sounds, and start playing music
explosionSound = Content.Load<SoundEffect>("Sound/explosion");
fuelCellPickupSound = Content.Load<SoundEffect>("Sound/fuelcell_pickup");
music = Content.Load<Song>("Sound/music");
MediaPlayer.Play(music);
//Initial spaceship starting location and rotation
spaceship.Position = new Vector3(0, 300, 1000);
spaceship.Rotation = Quaternion.Identity;
exhaustParticleEmitter = new ParticleEmitter(fireParticles, 1000, spaceship.Position);
}