animating a hero with a double key press as3 Flash Pro CS6 - actionscript-3

Question

Im creating a space shooter. Im trying to figure out how I can code/ run my movie clip (muzzle flash) when spacebar and a directional key are pressed at the same time.
This was my AS2 code using keyframes within Flash itself:
if(Key.isDown(Key.SPACE)){
this.gotoAndStop("20");
} else {
this.gotoAndStop("idle");
}
if(Key.isDown(Key.RIGHT)){
this._x += 5;
this.gotoAndStop("6");
}
if(Key.isDown(Key.SPACE)){
this.gotoAndStop("20");
}
if(Key.isDown(Key.LEFT)){
this._x -= 5;
this.gotoAndStop("6");
}
and so on...

Answer 1

If this was me, I would do something like this in AS3:
stop();
var velocity: Vector3D = new Vector3D(0,0,0);
var shooting: Boolean = false;
stage.addEventListener(KeyboardEvent.KEY_DOWN, function(evt: KeyboardEvent){
// have we moved on the X axis?
velocity.x = evt.keyCode == 37 ? -1: evt.keyCode == 39 ? 1: velocity.x;
// have we moved on the Y axis?
velocity.y = evt.keyCode == 40 ? -1: evt.keyCode == 38 ? 1: velocity.y;
// Have we shot?
shooting = evt.keyCode == 32 ? true : shooting;
});
stage.addEventListener(KeyboardEvent.KEY_UP, function(evt: KeyboardEvent){
// Have we finished moving on the X axis?
velocity.x = evt.keyCode == 37 || 39 ? 0 : velocity.x;
// Have we finished moving on the Y axis?
velocity.y = evt.keyCode == 40 || 38 ? 0 : velocity.y;
// have we finished shooting?
shooting = evt.keyCode == 32 ? false : shooting;
});
stage.addEventListener(Event.EXIT_FRAME, function(evt: Event){
// evaluate velocity and shooting and jump to the required keyframes.
trace(velocity, shooting);
});
The key to it is assessing which key was pressed in the two Keyboard event listeners and then at the end of the frame, then update the movieclip according to all of the data that has been gathered. I think this is important because you know that when the spaceship finally moves, it will definitely be in the most up to date state.
I also use a Vector3D to store the velocity of the spaceship as it has numerous helpful properties for calculating movement of objects such as Vector3D.scaleBy() for applying speed to the spacecraft and Vector3D.distance() for calculating the distance between the spaceship and an enemy which might be used for weapon accuracy or damage in relation to distance.