//Now here are the actual hit tests
//Bullets hit invaders
private bool BulletInvaderHitTest(Bullet thisBullet, Invader thisInvader)
{
//two rectangles are defined: one around the bullet, one around the invader
Rect recBullet = new Rect(Canvas.GetLeft(thisBullet), Canvas.GetTop(thisBullet), thisBullet.ActualWidth, thisBullet.ActualHeight);
Rect recInvader = new Rect(Canvas.GetLeft(thisInvader), Canvas.GetTop(thisInvader), thisInvader.ActualWidth, thisInvader.ActualHeight);
//The intersectsWith method is called on recBullet with the argument recInvader which returns true if the rectangles overlap.
//This result is returned to the condition statement calling the method and it is similar to a function in visual basic.
return recBullet.IntersectsWith(recInvader);
}
//the method the draw the aliens at the start of the game
private void drawAliens()
{
//first the embedded .png files are loaded into bitmap variables
BitmapImage bitInv1a = new BitmapImage();
bitInv1a.BeginInit();
bitInv1a.UriSource = new Uri("inv1a.png", UriKind.Relative);
bitInv1a.EndInit();
BitmapImage bitInv1b = new BitmapImage();
bitInv1b.BeginInit();
bitInv1b.UriSource = new Uri("inv1b.png", UriKind.Relative);
bitInv1b.EndInit();
BitmapImage bitInv2a = new BitmapImage();
bitInv2a.BeginInit();
bitInv2a.UriSource = new Uri("inv2a.png", UriKind.Relative);
bitInv2a.EndInit();
BitmapImage bitInv2b = new BitmapImage();
bitInv2b.BeginInit();
bitInv2b.UriSource = new Uri("inv2b.png", UriKind.Relative);
bitInv2b.EndInit();
BitmapImage bitInv3a = new BitmapImage();
bitInv3a.BeginInit();
bitInv3a.UriSource = new Uri("inv3a.png", UriKind.Relative);
bitInv3a.EndInit();
BitmapImage bitInv3b = new BitmapImage();
bitInv3b.BeginInit();
bitInv3b.UriSource = new Uri("inv3b.png", UriKind.Relative);
bitInv3b.EndInit();
BitmapImage bitBullet = new BitmapImage();
bitBullet.BeginInit();
bitBullet.UriSource = new Uri("bullet.png", UriKind.Relative);
bitBullet.EndInit();
//five rows of aliens
for (int j = 0; j < 5; j++)
{
//15 aliens per row
for (int i = 0; i < 15; i++)
{
//instanciates a new user control of the type Invader
Invader thisInvader = new Invader();
//using modular division aliens are created in 3 types
switch (j % 3)
{
case (0): thisInvader.image1.Source = bitInv1a; thisInvader.lives = 1; thisInvader.points = 100; thisInvader.flavour = 1; break;
case (1): thisInvader.image1.Source = bitInv2a; thisInvader.lives = 2; thisInvader.points = 200; thisInvader.flavour = 2; break;
case (2): thisInvader.image1.Source = bitInv3a; thisInvader.lives = 3; thisInvader.points = 300; thisInvader.flavour = 3; break;
}
//invader is added to the screen
cnvSpace.Children.Add(thisInvader);
//a reference to the invader is added to the typed list aliens
Aliens.Add(thisInvader);
//a horizontal gap of 5px between invaders (dimesnion is 30*30) plus an offset of 5px
Canvas.SetLeft(thisInvader, i * 35 + 5);
//vertical gap if 5px plus 40px offset
Canvas.SetTop(thisInvader, j * 35 + 40);
//z-index is set up so that game over will appear above the sprite
Canvas.SetZIndex(thisInvader, 0);
}
}
}