Actionscript 3 Making the character to Jump - actionscript-3

Question

I am making a platformer game. But I am having issue because whenever I pressed the spacebar to jump, the character will stuck in the mid-air. However, I can resolved the problem by holding spacebar and the character will land.
The issue is at mainJump() located inside Boy class.
I seen many people solved the problem by using action timeline, but my main problem is, are there anyway I can solve the problem by using an external class?
Main class
package
{
import flash.display.*;
import flash.text.*;
import flash.events.*;
import flash.utils.Timer;
import flash.text.*;
public class experimentingMain extends MovieClip
{
var count:Number = 0;
var myTimer:Timer = new Timer(10,count);
var classBoy:Boy;
//var activateGravity:gravity = new gravity();
var leftKey, rightKey, spaceKey, stopAnimation:Boolean;
public function experimentingMain()
{
myTimer.addEventListener(TimerEvent.TIMER, scoreUp);
myTimer.start();
classBoy = new Boy();
addChild(classBoy);
stage.addEventListener(KeyboardEvent.KEY_DOWN, pressTheDamnKey);
stage.addEventListener(KeyboardEvent.KEY_UP, liftTheDamnKey);
}
public function pressTheDamnKey(event:KeyboardEvent):void
{
if (event.keyCode == 37)
{
leftKey = true;
stopAnimation = false;
}
if (event.keyCode == 39)
{
rightKey = true;
stopAnimation = false;
}
if (event.keyCode == 32)
{
spaceKey = true;
stopAnimation = true;
}
}
public function liftTheDamnKey(event:KeyboardEvent):void
{
if (event.keyCode == 37)
{
leftKey = false;
stopAnimation = true;
}
if (event.keyCode == 39)
{
rightKey = false;
stopAnimation = true;
}
if (event.keyCode == 32)
{
spaceKey = false;
stopAnimation = true;
}
}
public function scoreUp(event:TimerEvent):void
{
scoreSystem.text = String("Score : "+myTimer.currentCount);
}
}
}
Boy class
package
{
import flash.display.*;
import flash.events.*;
public class Boy extends MovieClip
{
var leftKeyDown:Boolean = false;
var upKeyDown:Boolean = false;
var rightKeyDown:Boolean = false;
var downKeyDown:Boolean = false;
//the main character's speed
var mainSpeed:Number = 5;
//whether or not the main guy is jumping
var mainJumping:Boolean = false;
//how quickly should the jump start off
var jumpSpeedLimit:int = 40;
//the current speed of the jump;
var jumpSpeed:Number = 0;
var theCharacter:MovieClip;
var currentX,currentY:int;
public function Boy()
{
this.x = 600;
this.y = 540;
addEventListener(Event.ENTER_FRAME, boyMove);
}
public function boyMove(event:Event):void
{
currentX = this.x;
currentY = this.y;
if (MovieClip(parent).leftKey)
{
currentX += mainSpeed;
MovieClip(this).scaleX = 1;
}
if (MovieClip(parent).rightKey)
{
currentX -= mainSpeed;
MovieClip(this).scaleX = -1;
}
if (MovieClip(parent).spaceKey)
{
mainJump();
}
this.x = currentX;
this.y = currentY;
}
public function mainJump():void
{
currentY = this.y;
if (! mainJumping)
{
mainJumping = true;
jumpSpeed = jumpSpeedLimit * -1;
currentY += jumpSpeed;
}
else
{
if (jumpSpeed < 0)
{
jumpSpeed *= 1 - jumpSpeedLimit / 250;
if (jumpSpeed > -jumpSpeedLimit/12)
{
jumpSpeed *= -2;
}
}
}
if (jumpSpeed > 0 && jumpSpeed <= jumpSpeedLimit)
{
jumpSpeed *= 1 + jumpSpeedLimit / 120;
}
currentY += jumpSpeed;
if (currentY >= stage.stageHeight - MovieClip(this).height)
{
mainJumping = false;
currentY = stage.stageHeight - MovieClip(this).height;
}
}
}
}

Answer 1

First of all, formalize your code, eliminating sassy things like 'pressTheDamnKey,' which doesn't even describe the function very well because a function cannot press a key. That is an event handler and should be named either keyDownHandler or onKeyDown, nothing else.
Secondly, you rarely want to do any actual work in event handlers beyond the immediate concerns of the event data. Instead call out to the function which does the actual work. A handler handles the event, then calls the code which does the work. This separates out concerns nicely for when you want something else to be able to also make the little boy animate besides the enterFrameHandler, like perhaps a mouse.
I can imagine your trace log is getting filled up pretty quickly with "Score" lines since your timer is firing 100 times a second (10 milliseconds per). I would change that to not fire on a timer, but to be refreshed when the score actually changes.
The problem with the jumping, aside from spaghetti code, is that you are basing his movements upon whether the key is pressed or not by saving the state of the key press in a variable and having him continually inspect it. This is bad for a couple of reasons: 1. he should not need to reach out to his environment for information, it should be given to him by whatever object owns him or by objects that are responsible for telling him and 2. It requires you to continually hold down the spacebar or he will stop moving, since he checks to see if it is being held down (see problem 1).
I will address all these issues below, leaving out the scoring, which is another matter altogether.
package
{
import flash.display.*;
import flash.events.*;
import flash.text.*;
import flash.utils.*;
// Sprite is preferred if you are not using the timeline
public class Application extends Sprite
{
private var boy:Boy;
public function Application()
{
boy = new Boy();
addChild(boy);
boy.x = 600; // set these here, not in the boy
boy.y = 540;
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler );
}
public function keyDownHandler(event:KeyboardEvent):void
{
switch(event.keyCode)
{
case 32: boy.jump();
break;
case 37: boy.moveLeft();
break;
case 39: boy.moveRight();
break;
default:
// ignored
break;
}
}
public function keyUpHandler(event:KeyboardEvent):void
{
switch(event.keyCode)
{
// ignored for jumping (32)
case 37: // fall through
case 39: boy.stop();
break;
default:
// ignored
break;
}
}
}//class
}//package
package
{
import flash.display.*;
import flash.events.*;
// It is assumed that there is an asset in the library
// that is typed to a Boy, thus it will be loaded onto
// the stage by the owner
public class Boy extends Sprite
{
private var horzSpeed :Number = 0;
private var vertSpeed :Number = 0;
private var floorHeight :Number;
private var jumpHeight :Number;
private var amJumping :Boolean = false;
public function Boy()
{
addEventListener(Event.ENTER_FRAME, enterFrameHandler);
}
public function moveLeft():void
{
horzSpeed = -1;
}
public function moveRight():void
{
horzSpeed = 1;
}
public function stop():void
{
horzSpeed = 0;
}
public function jump():void
{
if (amJumping) return;
floorHeight = y;
jumpHeight = floorHeight + 20;
vertSpeed = 2;
amJumping = true;
animateJump();
}
private function enterFrameHandler(event:Event):void
{
animate();
}
private function animate():void
{
x += horzSpeed;
if( amJumping )
{
animateJump();
}
}
// Doing a simple version for this example.
// If you want an easier task of jumping with gravity,
// I recommend you employ Greensock's superb
// TweenLite tweening library.
private function animateJump():void
{
y += vertSpeed;
if( y >= jumpHeight )
{
y = jumpHeight;
vertSpeed = -2;
}
else if( y <= floorHeight )
{
y = floorHeight;
amJumping = false;
}
}
}//class
}//package
Another way to approach this, and probably the better way long-term, is for the boy to not even be responsible for moving himself. Instead, you would handle that in the parent, his owner or some special Animator class that is responsible for animating things on schedule. In this even more encapsulated paradigm, the boy is only responsible for updating his own internal look based upon the outside world telling him what is happening to him. He would no longer handle jumping internally, but instead would be responsible for doing things like animating things he owns, like his arms and legs.

Answer 2

You've got a mainJumping variable that is only true while the jump is running. Why not just use that?
if (MovieClip(parent).spaceKey || mainJumping)
{
mainJump();
}