Introduction

In the world of web-based games, Flash is king. However, one of the biggest drawbacks (for me at least), is that it hasn't been a very programmer-friendly platform. Adobe has changed all that with the release of the Flex 2 SDK. Read on as I take you through the steps to create Flash content using nothing but free command-line tools and a text editor.

What is Flex?

Adobe Flex is a software development kit that serves as an alternative to the Flash Professional application. The end result is the same- it creates Flash (.swf) movies. But the tools are much lower-level; they'll require more technical knowledge, while giving us more control over the final product.

Flex 1 was initially released in March 2004, but was too expensive for anyone but enterprise-level clients. With the release of Flex 2 in June 2006, Adobe has made the SDK free, making it the first version appropriate for indie developers.

Flex 2 can only create content for the new Flash 9 player. As of March 2007, the Adobe site lists Flash 9 penetration at around 83% (footnote 3), but this will certainly rise.

Download the SDK

Okay, let's get started.

First, the SDK requires that you have the Java SDK 1.4 or 1.5 installed. If you don't have those, head over and install that. Also, make sure you have the Flash 9 Player installed, available here.

Next, head over to this site, read and agree to the license, and download the file flex_2_sdk.zip. Find a nice place on your hard drive, and unzip.

You will probably want to add the /bin folder to your PATH environment variable. On windows, right click "My Computer", click the "Advanced" tab, click "Environment Variables", under "System variables" find "Path", then click "Edit". Add a semicolon to the last value, and type the full pathname of the Flex "bin" folder. For example, if I unzipped the files into the folder C:\flex_2_sdk, my path would look like:

On Mac/Linux, add a line to your "~/.profile" or "~/.bash_profile" file. The file might look like this:

Files and Tools

Before we do anything, let me go over the file types and tools that you'll be working with. If you have experience with Flash, you'll already be familiar with some of these.

• .SWF files - Flash movies. These are movies encoded in a binary, proprietary format. They can be played with the Adobe Flash Player, either standalone or embedded in a web page. These are your binaries, your end product.
• .AS files - ActionScript files. These are your source code files. Flex uses the ActionScript 3 language, which is based on ECMAScript revision 4.
• .MXML files - These describe a view/layout of Flex components. Every Flex application has at least one base-level MXML, and you can nest them as well.
• mxmlc tool - This is your compiler. It turns .MXML files into .SWF files.
• fdb tool - Flash debugging tool. Very similar to gdb or jdb. This tool is difficult to use manually, I recommend using other methods for debugging.

Now we're ready to start writing our app. Here is a sneak preview of what our process is:

Step 1: Create a .MXML file
Step 2: Add a custom component to your .MXML file, and make it take up the entire screen
Step 3: Define the behavior of your custom component by writing a .AS file
Step 4: Turn the whole thing into a movie with the mxmlc tool
Step 5: Play it

That doesn't sound too hard, right?

The Game Files