how do i change my main player in flash? - actionscript-3

Question

im new about scripting and i want to make a little free shop, my game is about a running car that have to avoid objects, so in the shop i want to that when the user press select http://prntscr.com/270ws5 the main car that is this one http://prntscr.com/270y45 , become the car that they selected, thanks
//These variables will note which keys are down
//We don't need the up or down key just yet
//but we will later
var leftKeyDown:Boolean = false;
var upKeyPressed:Boolean = false;
var rightKeyDown:Boolean = false;
var downKeyDown:Boolean = false;
//the main character's speed
var mainSpeed:Number = 7;
//whether or not the main guy is jumping
var mainJumping:Boolean = false;
//how quickly should the jump start off
var jumpSpeedLimit:int = 20;
//the current speed of the jump;
var jumpSpeed:Number = 0;
//adding a listener to mcMain which will make it move
//based on the key strokes that are down
player.addEventListener(Event.ENTER_FRAME, moveChar);
function moveChar(event:Event):void{
//if certain keys are down then move the character
if(leftKeyDown){
player.x -= mainSpeed;
}
if(rightKeyDown){
player.x += mainSpeed;
}
if(upPressed || mainJumping){
mainJump();
gotoAndStop(2)
gotoAndStop(3)
gotoAndStop(4)
gotoAndStop(5)
}
}
//listening for the keystrokes
//this listener will listen for down keystrokes
stage.addEventListener(KeyboardEvent.KEY_DOWN, checkKeysDown);
function checkKeysDown(event:KeyboardEvent):void{
//making the booleans true based on the keycode
//WASD Keys or arrow keys
if(event.keyCode == 37 || event.keyCode == 65){
leftKeyDown = true;
}
if(event.keyCode == 38 || event.keyCode == 87){
upPressed = true;
gotoAndStop(2)
}
if(event.keyCode == 39 || event.keyCode == 68){
rightKeyDown = true;
}
if(event.keyCode == 40 || event.keyCode == 83){
downKeyDown = true;
}
}
//this listener will listen for keys being released
stage.addEventListener(KeyboardEvent.KEY_UP, checkKeysUp);
function checkKeysUp(event:KeyboardEvent):void{
//making the booleans false based on the keycode
if(event.keyCode == 37 || event.keyCode == 65){
leftKeyDown = false;
}
if(event.keyCode == 38 || event.keyCode == 87){
upPressed = false;
gotoAndStop(2)
gotoAndStop(3)
gotoAndStop(4)
gotoAndStop(5)
}
if(event.keyCode == 39 || event.keyCode == 68){
rightKeyDown = false;
}
if(event.keyCode == 40 || event.keyCode == 83){
downKeyDown = false;
}
}
//jumping function
function mainJump():void{
//if main isn't already jumping
if(!mainJumping){
//then start jumping
mainJumping = true;
jumpSpeed = jumpSpeedLimit*-1;
player.y += jumpSpeed;
} else {
//then continue jumping if already in the air
//crazy math that I won't explain
if(jumpSpeed < 0){
jumpSpeed *= 1 - jumpSpeedLimit/75;
if(jumpSpeed > -jumpSpeedLimit/5){
jumpSpeed *= -1;
}
}
if(jumpSpeed > 0 && jumpSpeed <= jumpSpeedLimit){
jumpSpeed *= 1 + jumpSpeedLimit/50;
}
player.y += jumpSpeed;
//if main hits the floor, then stop jumping
//of course, we'll change this once we create the level
if(player.y >= stage.stageHeight - player.height){
mainJumping = false;
player.y = stage.stageHeight - player.height;
}
}
}
that is my car script, thanks a lot if someone can help me, to improve my script knowledge

Answer 1

You give a property to player's class of type MovieClip as it's movie clips you seem to have in your game to represent cars, which is then assigned an instance of a selected car. Then, whenever you want your player to gotoAndStop(), you address that to attached instance instead. Thus the instance will represent changeable graphics and the wrapper object (player) takes care of handling, collisions and other non-graphical stuff.
class Player extends Sprite {
private var _car:MovieClip; // the instance
public function Player() {
_car=new MovieClip();
addChild(_car);
}
public function get car():MovieClip { return _car; } // getter function
public function set car(value:MovieClip):void {
// setter function. We need to clean up our player from old car
if (!value) return; // null car - no wai
if (_car) removeChild(_car);
_car=value;
_car.x=0;
_car.y=0; // place car at zero relative to player
// this way you move the player, not the car,
// but MC playing is the car, not the player
addChild(_car);
}
...
}
Note that you can also relocate jump processing into Player class, so that you can just call player.jump() and don't care about the actual values, the player will then have to store the jumping constants, speeds, state (in midair or touching ground), etc etc.