Need help fixing player jumping diagonally Flash CS4

Question

I can't figure out why when I try and get my player to jump diagonally by pressing the right and up arrow key it does nothing, I've used trace to see if anything was happening and nothing was when they were used together.

Up won't work by itself or with right but when right is by itself it works.

player is named hero, platforms are named platform, platform2, platform3 etc

platforms are in the platform layer

stop();

var gravity:Number=5;  //Very important, allows player to fall 
var movex:Number=0; // Moving players X
// Moving player

stage.addEventListener(KeyboardEvent.KEY_DOWN, moveHero);

var speed=10;
function moveHero(event:KeyboardEvent) {
    if (event.keyCode==Keyboard.LEFT) {
        hero.x-=speed;
        hero.play();
    }

    if (event.keyCode==Keyboard.RIGHT) {
        hero.x+=speed;
        hero.play();
    }

}

hero.addEventListener(Event.ENTER_FRAME, testCollision2);

// Allowing player to jump when on platform
function testCollision2(e: Event) {

//Allowing player to jump when on platform continued
stage.addEventListener(KeyboardEvent.KEY_DOWN, moveHeroUP);

function moveHeroUP(event:KeyboardEvent) {
    if (hero.hitTestObject(platform) && event.keyCode==Keyboard.UP) {
        gravity=-50;
        hero.y=hero.y+gravity;
    } else if (hero.hitTestObject(platform2) && event.keyCode==Keyboard.UP) {
        gravity=-50;
        hero.y=hero.y+gravity;
    } else if (hero.hitTestObject(platform4) && event.keyCode==Keyboard.UP) {
        gravity=-50;
        hero.y=hero.y+gravity;
    }

    if(hero.hitTestObject(platform) && event.keyCode==Keyboard.UP && event.keyCode==Keyboard.RIGHT){
        movex = 20;
        hero.x = hero.x + movex;
        gravity =-50;
        hero.y = hero.y + gravity;
    }

}

I'm trying to get the player to jump in the code chunk at the very end

Flash CS4 AS3

Answer 1

To start, let's go through how you've set up this code and explain what's happening.

You have this line:

hero.addEventListener(Event.ENTER_FRAME, testCollision2);

Which is saying, every frame tick that hero exists, run the function testCollision2. Frame tick here doesn't relate to timeline frames, it relates to the frame rate of your application. So if that is set to 12, that function will run 12 times every second.

Inside testCollision2, you add another listener:

stage.addEventListener(KeyboardEvent.KEY_DOWN, moveHeroUP);

and create an inline function called moveHeroUP. So every frame tick, you create a new function, and attach it to a key down event. So (assuming 12 frames per second) 5 seconds into your application, you'll have 60 keyboard listeners all doing the same thing. This is also a memory leak (as you keep creating a new function every frame), so eventually your program will crash.

To get to the actual question, a keyboard event is tied to one specific key. This means the event's keyCode is only ever one key (the key that triggered the event). So doing something like (event.keyCode==Keyboard.UP && event.keyCode==Keyboard.RIGHT) will always be false because event.keyCode only ever holds one value.

A common approach to your situation, is to have one global key down and key up listener. Then use a dictionary to store which keys are currently down:

//create just one key down listener
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);

//create a dictionary to store key presses
var keyboardDown:Dictionary = new Dictionary();

function keyDownHandler(e:KeyboardEvent):void {
    keyboardDown[e.keyCode] = true;
}

function keyUpHandler(e:KeyboardEvent):void {
    keyboardDown[e.keyCode] = false;
}

What you're doing here, is when a key down event fires, you set the value in the dictionary to true (with the keycode as the dictionary key), then on the key up event you set it to false.

Now, in your ENTER_FRAME handler, you use the dictionary values to check for key combinations:

hero.addEventListener(Event.ENTER_FRAME, moveHero);

function moveHero(event:Event) {
    //DO ALL YOUR MOVEMENTS IN ONE ENTER FRAME FUNCTION

    if (keyboardDown[Keyboard.LEFT]) {
        hero.x-=speed;
        hero.play();
    }

    if (keyboardDown[Keyboard.RIGHT]) {
       hero.x+=speed;
       hero.play();
    }

    if (hero.hitTestObject(platform) && keyboardDown[Keyboard.UP]) {
        gravity=-50;
        hero.y=hero.y+gravity;
    } else if (hero.hitTestObject(platform2) && keyboardDown[Keyboard.UP]) {
        gravity=-50;
        hero.y=hero.y+gravity;
    } else if (hero.hitTestObject(platform4) && keyboardDown[Keyboard.UP]) {
        gravity=-50;
        hero.y=hero.y+gravity;
    }

    if(hero.hitTestObject(platform) && keyboardDown[Keyboard.UP] && keyboardDown[Keyboard.RIGHT]){
        movex = 20;
        hero.x = hero.x + movex;
        gravity =-50;
        hero.y = hero.y + gravity;
    }

}