We’re going to add a simple timer to our maze game that we’ve been working on. (If you’ve missed a few sessions, start here.)

We want the timer to start at 1000 and count down to the player’s imminent doom.

To set up the initial value for the timer, let’s create a variable called scarytimer.
var scarytimer:Number=1000;

Put that code at the very top, outside of any functions. If a variable is defined in a function, other functions will see it as undefined. So, at the top of the AcionScript, type in:
var scarytimer:Number=1000;
right above where you see
var tiles:Object = new Object({width:52, height:26});

The player will start with 1000 loops to be able to get to tile101, tile101 being our special tile from last time.

Now we need the player’s doom.

In the onEnterFrame function, we need to subtract from scarytimer each time the game loops in a frame.

Way back in the olden days when I programmed stone tablets for pterodactyls, we would write scarytimer=scarytimer-1 to subtract gradually from the variable with each loop.

ActionScript has simplified it with the code:
scarytimer--;
The two minuses tell ActionScript to subtract one increment from the variable.

Put scarytimer--; right above where you see input();

Variables get tricky when trying to determine what value they have. Run a trace on the variable to have the computer tell you what value scarytimer has.

scarytimer--;
trace(scarytimer);

Now the code will decrease scarytimer and then spit out its value to you.

Run your file right now to make sure your variable works. If it doesn’t, everything else will get nasty quickly.

We started with this great game engine and we edited the arrays to add walls at different locations on the map. This week we’re going to add a custom floor tile that:

• Checks to see if the hero is standing on the tile.
• If the hero is on the tile, sends the entire Flash timeline to the next frame.

First let’s make sure we know how to recognize the hero stepping on a tile.

1. Open up your project file from last week. (Remember: the original file can be found here if you were gone.)
2. Open up the project’s library.
3. Right-click/CTRL+click on the ’tile100′ movie clip in the library. Choose ‘Duplicate’.
4. Name it ’tile101′. Make sure to click the checkbox next to Linkage: Export for ActionScript.
5. Double-click the ’tile101′ movie clip to edit it. Double-click the square and select a new color from the paintbucket for it.
6. Click on Scene 1 to go back to the main timeline.
7. Click on the frame with all the ActionScript in it. To edit the ActionScript, click on the arrow in the frame’s Properties window.
8. Look for the code that reads:

   _root.onEnterFrame = function():Void
{
input(); // Handle keyboard movement
return;

   };
   Let’s add a message that pops up, showing that the exit was stepped on. We’ll use the trace function for that:
   _root.onEnterFrame = function():Void
{
input(); // Handle keyboard movement
if(canvas.map[hero.y][hero.x] == 101) trace("Exit");
return;

   };

   A message should pop up in the debugger window with the word “Exit” showing up while you step on the tile.

   Now that we can tell if the tile is being stepped on, see if you can figure out how to send the hero to a new map.

Isometric perspective is a way to use 2D images to create a 3D environment. Flash normally operates in 2D images; Chris Lindsey created a game engine in Flash to represent a 3D environment. The engine does require ActionScript 3, though, so it won’t run properly in ActionScript 2.

A game engine is not a game in itself- it is the power behind the game. Programmers will design an engine to run their video game and then license that engine to other game developers. Here’s a list of some of the current game engines out there.

Things to look at in this game engine:

1. There are no movie clips on the stage to begin with. The code places the movie clips onto the stage when you test the movie/make the .SWF file.
2. All of the code is in just one frame. You don’t have to search all over for it – this is really appreciated.
3. There’s a giant array of numbers.
   
   This is your map. If it says ‘200’, that’s a wall piece that gets placed. If it says ‘100’, that’s a floor piece.
   

Save a copy of the .FLA file so you have the original and then one to work with. Try editing the ‘hero’ movie clip. Draw your artwork on a new layer inside the movie clip. You can then delete the original box image layer. To help you out, you can turn the box layer into an outline by clicking on the colored box on the layer (in this picture it’s yellow).

Once you get used to how the artwork is set up, try expanding the map by adding a new line of 100s and 200s in the ActionScript.

Click on the game to play it. Use the arrow keys to move your character around.

The .FLA file with all of the code can be found by clicking here.