//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);
}
//bullets hit shield elements
private bool BulletShieldElementHitTest(Bullet thisBullet, shieldElement thisShieldElement)
{
Rect recBullet = new Rect(Canvas.GetLeft(thisBullet), Canvas.GetTop(thisBullet), thisBullet.ActualWidth, thisBullet.ActualHeight);
Rect recShieldElement = new Rect(Canvas.GetLeft(thisShieldElement), Canvas.GetTop(thisShieldElement), 10, 20);
return recBullet.IntersectsWith(recShieldElement);
}
//here is the fire bullet method
private void fireBullet()
{
//instanciate a new bullet user control
Bullet newBullet = new Bullet();
//put it on the screen andd add refernece to the bullets list
cnvSpace.Children.Add(newBullet);
Bullets.Add(newBullet);
//set its position to that of the centre of the gunner
Canvas.SetLeft(newBullet, Canvas.GetLeft(imgGunner) + imgGunner.ActualWidth*.5);
Canvas.SetTop(newBullet, Canvas.GetTop(imgGunner));
}