Flash MX 2004 Games : Art to ActionScript

Chapter 1: Your first game
Adding the bats
At this stage you have an option; you can try yourself to create the bat as shown in Figure 1.15 or you
can take the easy way out and open the project on the CD ‘Examples/Chapter01/Pingpong03.fla’.
Each bat uses the same symbol, with the left bat flipped horizontally by using
‘Modify/Transform/Flip Horizontal’ to create the right bat.
Figure 1.14 Selecting Edit Symbols Figure 1.15 The bat
Adding a little code
Now is the time to start to enter a little ActionScript. Click on the right-hand bat to select it, and
then open the Actions panel either by selecting ‘Window/Development Panels/Actions’, or by
pressing F9, or by clicking on the blue arrow icon at the right of the Properties panel. You should
see something similar to Figure 1.16 on page 8.
Fear not if the sight of all this gibberish fills you with dread, we will examine this code a bit at
a time. Firstly, the opening line:
onClipEvent(enterFrame){
What does this mean? Remember that we created a symbol, and we chose to make this symbol
a ‘Movie Clip’. Movie clips can have code attached to them and one of the ways you can add
this code is by clicking on the symbol, selecting actions then adding an ‘onClipEvent’. The curly
brackets { and } contain a section of code, in this case they contain all the code that occurs for
the ‘onClipEvent’. An ‘onClipEvent’ can be passed a little information in the form of a parameter.
The syntax for Flash is very similar to the syntax for JavaScript, which is often used by pages that
you will view in an Internet browser. A parameter is contained within regular brackets, ( and ).
In this example the parameter passed is ‘enterFrame’; this occurs as the timer flips on to the next
time segment. If you set the movie frame rate to 20, then this section of code will run 20 times
a second. If this sounds a lot, bear in mind that many commercial games aim for frame rates of
50 times a second or above. The higher the frame rate the smoother an animation will appear;
however, the computer hardware must be able to sustain this level of computation. For now we
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