Building Games in Flash 5 - Part 3 - Enemies and collisions - Page 11

Step 6: A restart button and limited lasers

Restart button

So we need to add in a restart button at the end of the game, which will restart the game.

On the main timeline add in another new layer and call it restart. Insert a blank keyframe on the third frame of this new layer (Insert > Blank keyframe). With this new keyframe selected draw a filled rectangle on the stage, this will be the restart button. Add the text RESTART on top of this rectangle (as shown on the right). Then select both the rectangle and the text and convert to a button symbol (Insert > Convert to symbol , give it the name restart and select behaviour button)

Now we are going to assign some code to the button. Select the restart button and open the actions window (Window > Actions).
Type the following code:

on ( release ) {
  gotoAndPlay (1);
}

This just tells flash to go back to the first frame of the main timeline when the button is released which will result in the game restarting.

Limited lasers

We want to limit the number of lasers that are on the stage at any one point it time. The code will limit the game to having a maximum of 4 lasers on the stage, but you can easily change this to any number you want.

We limit the lasers by keeping a count of how many lasers are on the stage and we wont duplicate a new laser if there are already 4 lasers on the stage. The concept is quite simple; when we create a new laser movieclip we will add one to a laser counter, when the laser moves off the stage we will reduce the laser counter by one, thus we always have a count of how many lasers are on the stage.

As the code for duplicating lasers is contained within the spaceship clipEvents we will need to modify that code.

Select the spaceship and open the actions window (Window > Actions).