// take some damage when a projectile collides with the building
public void OnCollisionEnter(Collision collision)
{
Projectile projectile;
if ((projectile = collision.gameObject.GetComponent <Projectile>()) != null)
{
// take damage. heath will fire an event if the damage is equal to 0
health.takeDamage(projectile.damageAmount);
// destroy the projectile
projectile.destroySelf();
}
}
