XNA 4.0 Game Development by Example Beginner's Guide

Time for action – enemy update and draw

1. Add the Update() method to the Enemy class:

   public void Update(GameTime gameTime)
   {
       if (IsActive())
       {
           Vector2 heading = currentWaypoint - EnemySprite.Location;
           if (heading != Vector2.Zero)
           {
               heading.Normalize();
           }
           heading *= speed;
           EnemySprite.Velocity = heading;
           previousLocation = EnemySprite.Location;
           EnemySprite.Update(gameTime);
           EnemySprite.Rotation = 
               (float)Math.Atan2(
               EnemySprite.Location.Y - previousLocation.Y, 
               EnemySprite.Location.X - previousLocation.X);
   
           if (WaypointReached())
           {
               if (waypoints.Count > 0)
               {
                   currentWaypoint = waypoints.Dequeue();
               }
           }
       }
   }

2. Add the Draw() method to the Enemy class:

   public void Draw(SpriteBatch spriteBatch)
   {
       if (IsActive())
       {
           EnemySprite.Draw(spriteBatch);
       }
   }

What just ...