   XNA - Need help. Sprites spawning  at intervals
  Okay, before I begin, I should say I've been coming to GameDev.net for a while and visit the boards quite frequently. Right now I am at my local community college to get an Associates degree in game design before deciding to move onto a 4 year college.Right now I am in my XNA class. The course is coming to an end and we have our final project. The basic guidelines are that it has to be a game we create, and we have to treat this as if we were going to publish it. Meaning, we can use any sprites, textures, sounds, code, etc., as long as it is royalty free/open source and we wouldn't be breaking any licenses.============================The game I'm working on is a basic 2d space shooter. Think Galaga/Space Invaders. The player is on the left side of the screen, and can only move up or down. Instead of enemies moving at random speeds and paths, it is a constant wave of blocks that are move steadily towards the player, from the right side of the screen.Here is a screenshot of the game so you get an idea of what I'm doing  Right now I am working on increasing the speed at which the bricks move over time. So say after 60 seconds, the bricks move twice as fast, at 120 seconds, they move 3x as fast, etc. I got the coding down for the timer as to when to increase the speed of the bricks, but the problem I am having is how often the bricks should spawn.Right now, the bricks spawn in columns with 7 rows. Once one entire column is created, it creates the next column of bricks right after that.Currently the way I spawn the bricks is as follows:public static bool CheckSpawn() { for (int i = 0; i < m_Bricks.Length; i++)  {if (m_Bricks.IsActive){   if (m_Bricks.Location.X == 1270)  return true;}   }  return false;  }The bricks spawn at an X position of 1300 (off the screen). The bricks are 30 pixels wide. Thus, when the left side edge of the brick hits 1270, it has moved far away enough to spawn the next column of bricks without overlap. There are a few problems I am running into with this.1. It has to check each and every brick to see if it hits that point, so I'm not sure if this will end up causing lag or delays in the long run.2. The rate at which the bricks move is simply something like Location.X -= Speed;So if end up making speed, say 7, it will never hit pixel 1270, it will hit 1272 then 1265, thus never spawning the next set of bricks. 3. I implemented a power up feature for the gameplay. Upon hitting a button, the player can slow the bricks back down for a period of time. However, if the bricks are moving at a rate of say 3, and the bricks are at pixel 1273, upon hitting the button, they will drop speed to 2, and now hit pixel 1271 and 1269. Which will then cause no more bricks to be added.Can anyone enlighten me as to how to fix this? I would really appreciate any help.Thanks a bunch!