Flash MX 2004 Games : Art to ActionScript

Chapter 17: Platformers
game much easier. When in debug mode several extra keys are used. The shift key causes the
sprite to move up the screen by one pixel for each screen redraw. The control key works in
the opposite direction. The space bar fixes the up and down movement set by the shift and control
keys. The tab key forces the character into a distinct mode and reactivates ‘usercontrol’, a variable
that is used to activate and deactivate keyboard input. If the caps lock key is down then the variable
‘tracemotion’ is set to true. This causes dump of the location of the sprite to be sent to the output
window. The value of the variable is used within another function that actually does this work,
which we will examine later.
The bulk of the code is inside the ‘Cat’ clip on frame 1. Before we examine that, take a look at
the timeline for the ‘Cat’ movie clip. There are 14 labels, each one indicating the first frame of an
animation. Within the Control layer there are a few small ActionScripts that set variables specific
to certain actions or reset the action; we will examine these later. The labels used are:
WalkRight, FallRight, JumpRight, LandRight, StopRight, StartRight, TurnRight
WalkLeft, FallLeft, JumpLeft, LandLeft, StopLeft, StartLeft, TurnLeft
The code on frame 1 starts with some simple initialization, but most of the code defines functions
that are used to control the character. Both ‘userAction’ and ‘move’ are called by the ‘onClipEvent’
ActionScript.
1 //Init variables
2 JUMP = 1;
3 TURNLEFT = 2;
4 STARTRIGHT = 3;
5 WALKRIGHT = 4;
6 FALLRIGHT = 5;
7 JUMPRIGHT = 6;
8 LANDRIGHT = 7;
9 STOPRIGHT = 8;
10 TURNRIGHT = 9;
11 STARTLEFT = 10;
12 WALKLEFT = 11;
13 FALLLEFT = 12;
14 JUMPLEFT = 13;
15 LANDLEFT = 14;
16 STOPLEFT = 15;
17 HALT = 16;
18 actionNames = new Array(
19 "No action", "Jump", "TurnLeft", "StartRight",
20 "WalkRight", "FallRight", "JumpRight", "LandRight",
21 "StopRight", "TurnRight", "StartLeft", "WalkLeft",
22 "FallLeft", "JumpLeft", "LandLeft", "StopLeft",
23 "Halt");
24 x = 0;
25 y = 0;
26 jumping = false;
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