私はフラッシュの初心者で、現在問題があります。スペースインベーダーのようなゲームを作っています。はじめのうちはよかった。ただし、キャラクターが敵に命中すると、エラーが発生します。
タイプ エラー:
エラー #1009: null オブジェクト参照のプロパティまたはメソッドにアクセスできません。_fla::MainTimeline/frame1126() で flash.display::MovieClip/gotoAndStop() で Enemy/eFrame() で
何が悪いのかわからない。誰でも私を助けることができますか？
タイムラインのソースはこちら
stop();
//these booleans will check which keys are down
var leftDown:Boolean = false;
var upDown:Boolean = false;
var rightDown:Boolean = false;
var downDown:Boolean = false;
//how fast the character will be able to go
var mainSpeed:int = 5;
//how much time before allowed to shoot again
var cTime:int = 0;
//the time it has to reach in order to be allowed to shoot (in frames)
var cLimit:int = 12;
//whether or not the user is allowed to shoot
var shootAllow:Boolean = true;
//how much time before another enemy is made
var enemyTime:int = 0;
//how much time needed to make an enemy
//it should be more than the shooting rate
//or else killing all of the enemies would
//be impossible :O
var enemyLimit:int = 16;
//the player's score
var score:int = 0;
//this movieclip will hold all of the bullets
var bulletContainer:MovieClip = new MovieClip();
addChild(bulletContainer);
//whether or not the game is over
var gameOver:Boolean = false;
//adding a listener to mcMain that will move the character
mcMain.addEventListener(Event.ENTER_FRAME, moveChar);
function moveChar(event:Event):void{
//checking if the key booleans are true then moving
//the character based on the keys
if(leftDown){
mcMain.x -= mainSpeed;
}
if(upDown){
mcMain.y -= mainSpeed;
}
if(rightDown){
mcMain.x += mainSpeed;
}
if(downDown){
mcMain.y += mainSpeed;
}
//keeping the main character within bounds
if(mcMain.x <= 0){
mcMain.x += mainSpeed;
}
if(mcMain.y <= 0){
mcMain.y += mainSpeed;
}
if(mcMain.x >= stage.stageWidth - mcMain.width){
mcMain.x -= mainSpeed;
}
if(mcMain.y >= stage.stageHeight - mcMain.height){
mcMain.y -= mainSpeed;
}
//Incrementing the cTime
//checking if cTime has reached the limit yet
if(cTime < cLimit){
cTime ++;
} else {
//if it has, then allow the user to shoot
shootAllow = true;
//and reset cTime
cTime = 0;
}
//adding enemies to stage
if(enemyTime < enemyLimit){
//if time hasn't reached the limit, then just increment
enemyTime ++;
} else {
//defining a variable which will hold the new enemy
var newEnemy = new Enemy();
//making the enemy offstage when it is created
newEnemy.y = -1 * newEnemy.height;
//making the enemy's x coordinates random
//the "int" function will act the same as Math.floor but a bit faster
newEnemy.x = int(Math.random()*(stage.stageWidth - newEnemy.width));
//then add the enemy to stage
addChild(newEnemy);
//and reset the enemyTime
enemyTime = 0;
}
//updating the score text
txtScore.text = 'Score: '+score;
}
//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){
leftDown = true;
}
if(event.keyCode == 38 || event.keyCode == 87){
upDown = true;
}
if(event.keyCode == 39 || event.keyCode == 68){
rightDown = true;
}
if(event.keyCode == 40 || event.keyCode == 83){
downDown = true;
}
//checking if the space bar is pressed and shooting is allowed
if(event.keyCode == 32 && shootAllow){
//making it so the user can't shoot for a bit
shootAllow = false;
//declaring a variable to be a new Bullet
var newBullet:Bullet = new Bullet();
//changing the bullet's coordinates
newBullet.x = mcMain.x + mcMain.width/2 - newBullet.width/2;
newBullet.y = mcMain.y;
//then we add the bullet to stage
bulletContainer.addChild(newBullet);
}
}
//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){
leftDown = false;
}
if(event.keyCode == 38 || event.keyCode == 87){
upDown = false;
}
if(event.keyCode == 39 || event.keyCode == 68){
rightDown = false;
}
if(event.keyCode == 40 || event.keyCode == 83){
downDown = false;
}
}
ENEMY のソース コードは次のとおりです。
//This is the basic skeleton that all classes must have
package{
//we have to import certain display objects and events
import flash.display.MovieClip;
import flash.events.*;
//this just means that Enemy will act like a MovieClip
public class Enemy extends MovieClip{
//VARIABLES
//this will act as the root of the document
//so we can easily reference it within the class
private var _root:Object;
//how quickly the enemy will move
private var speed:int = 5;
//this function will run every time the Bullet is added
//to the stage
public function Enemy(){
//adding events to this class
//functions that will run only when the MC is added
addEventListener(Event.ADDED, beginClass);
//functions that will run on enter frame
addEventListener(Event.ENTER_FRAME, eFrame);
}
private function beginClass(event:Event):void{
_root = MovieClip(root);
}
private function eFrame(event:Event):void{
//moving the bullet up screen
y += speed;
//making the bullet be removed if it goes off stage
if(this.y > stage.stageHeight){
removeEventListener(Event.ENTER_FRAME, eFrame);
_root.removeChild(this);
}
//checking if it is touching any bullets
//we will have to run a for loop because there will be multiple bullets
for(var i:int = 0;i<_root.bulletContainer.numChildren;i++){
//numChildren is just the amount of movieclips within
//the bulletContainer.
//we define a variable that will be the bullet that we are currently
//hit testing.
var bulletTarget:MovieClip = _root.bulletContainer.getChildAt(i);
//now we hit test
if(hitTestObject(bulletTarget)){
//remove this from the stage if it touches a bullet
removeEventListener(Event.ENTER_FRAME, eFrame);
_root.removeChild(this);
//also remove the bullet and its listeners
_root.bulletContainer.removeChild(bulletTarget);
bulletTarget.removeListeners();
//up the score
_root.score += 5;
}
}
//hit testing with the user
if(hitTestObject(_root.mcMain)){
//losing the game
_root.gameOver = true;
_root.gotoAndStop('lose');
}
if(_root.gameOver){
removeEventListener(Event.ENTER_FRAME, eFrame);
this.parent.removeChild(this);
}
}
public function removeListeners():void{
this.removeEventListener(Event.ENTER_FRAME, eFrame);
}
}
}