I'll begin by saying that I've got hardly any experience with ActionScript3, and I've only just started with it by attempting to create a platformer using a tutorial. What I'm trying to do at the moment is have a Start scene in my game, where the player can start the game, quit the game etc, however, I run into this problem when pressing on the MovieClip button: "TypeError: Error #1009: Cannot access a property or method of a null object reference. at GAMEMAIN_fla::MainTimeline/loop()" I've looked at similiar questions on here before, however, they were more personalised towards the code that was written within the post, and I was unable to find any general fixes to this problem. On my Start scene, I've just got a Start button in the form of a MovieClip under the instance name of btnx, with the following code: stop();
btnx.addEventListener(MouseEvent.CLICK, myClick);
function myClick(event:MouseEvent) {
btnx.removeEventListener(MouseEvent.CLICK, myClick);
gotoAndPlay(0,"Game");
}
And on the game itself, I've got this code (I didn't come up with the code, I just followed a tutorial) var leftPressed:Boolean = false;
var rightPressed:Boolean = false;
var upPressed:Boolean = false;
var downPressed:Boolean = false;
var leftBumping:Boolean = false;
var rightBumping:Boolean = false;
var upBumping:Boolean = false;
var downBumping:Boolean = false;
var leftBumpPoint:Point = new Point(-30, -55);
var rightBumpPoint:Point = new Point(30, -55);
var upBumpPoint:Point = new Point(0, -120);
var downBumpPoint:Point = new Point(0, 0);
var scrollX:Number = 0;
var scrollY:Number = 500;
var xSpeed:Number = 0;
var ySpeed:Number = 0;
var speedConstant:Number = 4;
var frictionConstant:Number = 0.9;
var gravityConstant:Number = 1.8;
var jumpConstant:Number = -35;
var maxSpeedConstant:Number = 18;
var doubleJumpReady:Boolean = false;
var upReleasedInAir:Boolean = false;
var keyCollected:Boolean = false;
var doorOpen:Boolean = false;
var currentLevel:int = 1;
var animationState:String = "idle";
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyDownHandler);
stage.addEventListener(KeyboardEvent.KEY_UP, keyUpHandler);
stage.addEventListener(Event.ENTER_FRAME, loop);
function loop(e:Event😞void{
if(back.collisions.hitTestPoint(player.x + leftBumpPoint.x, player.y + leftBumpPoint.y, true)){
//trace("leftBumping");
leftBumping = true;
} else {
leftBumping = false;
}
if(back.collisions.hitTestPoint(player.x + rightBumpPoint.x, player.y + rightBumpPoint.y, true)){
//trace("rightBumping");
rightBumping = true;
} else {
rightBumping = false;
}
if(back.collisions.hitTestPoint(player.x + upBumpPoint.x, player.y + upBumpPoint.y, true)){
//trace("upBumping");
upBumping = true;
} else {
upBumping = false;
}
if(back.collisions.hitTestPoint(player.x + downBumpPoint.x, player.y + downBumpPoint.y, true)){
//trace("downBumping");
downBumping = true;
} else {
downBumping = false;
}
if(leftPressed){
xSpeed -= speedConstant;
player.scaleX = -1;
} else if(rightPressed){
xSpeed += speedConstant;
player.scaleX = 1;
}
/*if(upPressed){
ySpeed -= speedConstant;
} else if(downPressed){
ySpeed += speedConstant;
} */
if(leftBumping){
if(xSpeed < 0){
xSpeed *= -0.5;
}
}
if(rightBumping){
if(xSpeed > 0){
xSpeed *= -0.5;
}
}
if(upBumping){
if(ySpeed < 0){
ySpeed *= -0.5;
}
}
if(downBumping){ //if we are touching the floor
if(ySpeed > 0){
ySpeed = 0; //set the y speed to zero
}
if(upPressed){ //and if the up arrow is pressed
ySpeed = jumpConstant; //set the y speed to the jump constant
}
//DOUBLE JUMP
if(upReleasedInAir == true){
upReleasedInAir = false;
}
if(doubleJumpReady == false){
doubleJumpReady = true;
}
} else { //if we are not touching the floor
ySpeed += gravityConstant; //accelerate downwards
//DOUBLE JUMP
if(upPressed == false && upReleasedInAir == false){
upReleasedInAir = true;
//trace("upReleasedInAir");
}
if(doubleJumpReady && upReleasedInAir){
if(upPressed){ //and if the up arrow is pressed
//trace("doubleJump!");
doubleJumpReady = false;
ySpeed = jumpConstant; //set the y speed to the jump constant
}
}
}
if(keyCollected == false){
if(player.hitTestObject(back.other.doorKey)){
back.other.doorKey.visible = false;
keyCollected = true;
trace("key collected");
}
}
if(doorOpen == false){
if(keyCollected == true){
if(player.hitTestObject(back.other.lockedDoor)){
back.other.lockedDoor.gotoAndStop(2);
doorOpen = true;
trace("door open");
}
}
}
if(xSpeed > maxSpeedConstant){ //moving right
xSpeed = maxSpeedConstant;
} else if(xSpeed < (maxSpeedConstant * -1)){ //moving left
xSpeed = (maxSpeedConstant * -1);
}
xSpeed *= frictionConstant;
ySpeed *= frictionConstant;
if(Math.abs(xSpeed) < 0.5){
xSpeed = 0;
}
scrollX -= xSpeed;
scrollY -= ySpeed;
back.x = scrollX;
back.y = scrollY;
sky.x = scrollX * 0.2;
sky.y = scrollY * 0.2;
if( ( leftPressed || rightPressed || xSpeed > speedConstant || xSpeed < speedConstant *-1 ) && downBumping){
animationState = "running";
} else if(downBumping){
animationState = "idle";
} else {
animationState = "jumping";
}
if(player.currentLabel != animationState){
player.gotoAndStop(animationState);
}
}
function nextLevel():void{
currentLevel++;
trace("Next Level: " + currentLevel);
if(currentLevel == 2){
gotoLevel2();
}
else if (currentLevel == 3){
gotoLevel3();
}
// can be extended...
// else if(currentLevel == 3) { gotoLevel3(); } // etc, etc.
}
function gotoLevel2():void{
back.other.gotoAndStop(2);
back.visuals.gotoAndStop(2);
back.collisions.gotoAndStop(2);
scrollX = 0;
scrollY = 500;
keyCollected = false;
back.other.doorKey.visible = true;
doorOpen = false;
back.other.lockedDoor.gotoAndStop(1);
}
function gotoLevel3():void{
back.other.gotoAndStop(3);
back.visuals.gotoAndStop(3);
back.collisions.gotoAndStop(3);
scrollX = 0;
scrollY = 500;
keyCollected = false;
back.other.doorKey.visible = true;
doorOpen = false;
back.other.lockedDoor.gotoAndStop(1);
}
function keyDownHandler(e:KeyboardEvent😞void{
if(e.keyCode == Keyboard.LEFT){
leftPressed = true;
} else if(e.keyCode == Keyboard.RIGHT){
rightPressed = true;
} else if(e.keyCode == Keyboard.UP){
upPressed = true;
} else if(e.keyCode == Keyboard.DOWN){
downPressed = true;
if(doorOpen && player.hitTestObject(back.other.lockedDoor)){
//proceed to the next level if the player is touching an open door
nextLevel();
}
}
}
function keyUpHandler(e:KeyboardEvent😞void{
if(e.keyCode == Keyboard.LEFT){
leftPressed = false;
} else if(e.keyCode == Keyboard.RIGHT){
rightPressed = false;
} else if(e.keyCode == Keyboard.UP){
upPressed = false;
} else if(e.keyCode == Keyboard.DOWN){
downPressed = false;
}
}
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1 Correct answer
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