AS3 - Game Timer not calculating start time properly - actionscript-3

Question

I'm building a game in AS3 based off of Gary Rosenzweig's latest Actionscript 3 book. It has a game timer issue, not just mine but his demo too, that I can't figure out.
The game is like Asteroids where four rocks are placed in the corners of the stage at the beginning and then start moving randomly around the stage. The problem is the timer used is started the moment that the flash file starts not the moment the player clicks the start button. So if you are on the start screen for 5 seconds before you click play when the game actually begins the rocks are where they would be after 5 seconds of play, which could be right over the player.
I've posted the parts of the code that I think apply. Could someone please tell me how to modify this so that when the player actually starts the game the rocks start in their proper places. I'm pretty sure it's the last function that I've included that is the problem but I've included other related parts to give you a more complete picture.
package {
import flash.display.*;
import flash.events.*;
import flash.events.TouchEvent;
import flash.ui.Multitouch;
import flash.ui.MultitouchInputMode;
import flash.text.*;
import flash.utils.getTimer;
import flash.utils.Timer;
import flash.geom.Point;
import flash.net.SharedObject;
import flash.media.Sound;
import flash.media.SoundMixer;
import flash.media.SoundTransform;
import flash.media.SoundChannel;
Multitouch.inputMode = MultitouchInputMode.TOUCH_POINT;
public class VirusDefender extends MovieClip {
static const shipRotationSpeed:Number = .1;
static const rockSpeedStart:Number = .03;
static const rockSpeedIncrease:Number = .01;
static const missileSpeed:Number = .2;
static const thrustPower:Number = .15;
static const shipRadius:Number = 20;
static const startingShips:uint = 3;
// game objects
private var ship:Ship;
private var rocks:Array;
private var missiles:Array;
// animation timer
private var lastTime:uint;
// arrow keys
private var rightArrow:Boolean = false;
private var leftArrow:Boolean = false;
private var upArrow:Boolean = false;
// ship velocity
private var shipMoveX:Number;
private var shipMoveY:Number;
// timers
private var delayTimer:Timer;
private var shieldTimer:Timer;
// game mode
private var gameMode:String;
private var shieldOn:Boolean;
// ships and shields
private var shipsLeft:uint;
private var shieldsLeft:uint;
private var shipIcons:Array;
private var shieldIcons:Array;
private var scoreDisplay:TextField;
// score and level
private var gameScore:Number;
private var gameLevel:uint;
// sprites
private var gameObjects:Sprite;
private var scoreObjects:Sprite;
var gameBackground:GameBackground = new GameBackground();
// sounds
var sndFire:fire_sound;
var sndFireChannel:SoundChannel;
var sndThruster:thruster_sound;
var sndThrusterChannel:SoundChannel;
var sndShield:shield_sound;
var sndShieldChannel:SoundChannel;
var sndExplosion:explosion_sound;
var sndExplosionChannel:SoundChannel;
var sndBubble:bubble_sound;
var sndBubbleChannel:SoundChannel;
// start the game
public function startSpaceRocks() {
// set up sprites
addChild(gameBackground);
setChildIndex(gameBackground,0); // I added this
gameObjects = new Sprite();
addChild(gameObjects);
scoreObjects = new Sprite();
addChild(scoreObjects);
// reset score objects
gameLevel = 1;
shipsLeft = startingShips;
gameScore = 0;
createShipIcons();
createScoreDisplay();
// set up listeners
trace("add moveGameObjects event listener");
addEventListener(Event.ENTER_FRAME,moveGameObjects);
leftButton.addEventListener(TouchEvent.TOUCH_OVER,leftPress);
leftButton.addEventListener(TouchEvent.TOUCH_OUT,leftRelease);
rightButton.addEventListener(TouchEvent.TOUCH_OVER,rightPress);
rightButton.addEventListener(TouchEvent.TOUCH_OUT,rightRelease);
thrusterButton.addEventListener(TouchEvent.TOUCH_OVER,thrusterPress);
thrusterButton.addEventListener(TouchEvent.TOUCH_OUT,thrusterRelease);
shieldButton.addEventListener(TouchEvent.TOUCH_OVER,shieldPress);
fireButton.addEventListener(TouchEvent.TOUCH_OVER,firePress);
// Left Button
function leftPress(event:TouchEvent):void{
leftArrow = true;
}
function leftRelease(event:TouchEvent):void{
leftArrow = false;
}
// Right button
function rightPress(event:TouchEvent):void{
rightArrow = true;
}
function rightRelease(event:TouchEvent):void{
rightArrow = false;
}
// Thruster button
function thrusterPress(event:TouchEvent):void{
sndThruster=new thruster_sound();
sndThrusterChannel=sndThruster.play();
upArrow = true;
if (gameMode == "play") ship.gotoAndStop(2);
}
function thrusterRelease(event:TouchEvent):void{
sndThrusterChannel.stop();
upArrow = false;
if (gameMode == "play") ship.gotoAndStop(1);
}
// Fire button
function firePress(event:TouchEvent):void{
sndFire=new fire_sound();
sndFireChannel=sndFire.play();
newMissile();
}
// Shield button
function shieldPress(event:TouchEvent):void{
startShield(false);
}
// start
gameMode = "delay";
trace("gameMode - delay");
shieldOn = false;
missiles = new Array();
trace("nextRockWave fired");
nextRockWave(null);
newShip(null);
}
// SCORE OBJECTS
// draw number of ships left
public function createShipIcons() {
shipIcons = new Array();
for(var i:uint=0;i<shipsLeft;i++) {
var newShip:ShipIcon = new ShipIcon();
newShip.x = 165+i*25; //165
newShip.y = 273; //273
scoreObjects.addChild(newShip);
shipIcons.push(newShip);
}
}
// draw number of shields left
public function createShieldIcons() {
shieldIcons = new Array();
for(var i:uint=0;i<shieldsLeft;i++) {
var newShield:ShieldIcon = new ShieldIcon();
newShield.x = 310-i*25; //530
newShield.y = 273; //15
scoreObjects.addChild(newShield);
shieldIcons.push(newShield);
}
}
// put the numerical score at the upper right
public function createScoreDisplay() {
updateScore();
}
// new score to show
public function updateScore() {
score.text = addCommaInNumber(gameScore);
}
// remove a ship icon
public function removeShipIcon() {
scoreObjects.removeChild(shipIcons.pop());
}
// remove a shield icon
public function removeShieldIcon() {
scoreObjects.removeChild(shieldIcons.pop());
}
// remove the rest of the ship icons
public function removeAllShipIcons() {
while (shipIcons.length > 0) {
removeShipIcon();
}
}
// remove the rest of the shield icons
public function removeAllShieldIcons() {
while (shieldIcons.length > 0) {
removeShieldIcon();
}
}
// SHIP CREATION AND MOVEMENT
// create a new ship
public function newShip(event:TimerEvent) {
// if ship exists, remove it
if (ship != null) {
gameObjects.removeChild(ship);
ship = null;
}
// no more ships
if (shipsLeft < 1) {
endGame();
return;
}
// create, position, and add new ship
ship = new Ship();
ship.gotoAndStop(1);
ship.x = 240; //275
ship.y = 160; //200
ship.rotation = -90;
ship.shield.visible = false;
gameObjects.addChild(ship);
// set up ship properties
shipMoveX = 0.0;
shipMoveY = 0.0;
gameMode = "play";
// set up shields
shieldsLeft = 3;
createShieldIcons();
// all lives but the first start with a free shield
if (shipsLeft != startingShips) {
startShield(true);
sndShield=new shield_sound();
sndShieldChannel=sndShield.play();
}
}
// animate ship
public function moveShip(timeDiff:uint) {
// rotate and thrust
if (leftArrow) {
ship.rotation -= shipRotationSpeed*timeDiff;
} else if (rightArrow) {
ship.rotation += shipRotationSpeed*timeDiff;
} else if (upArrow) {
shipMoveX += Math.cos(Math.PI*ship.rotation/180)*thrustPower;
shipMoveY += Math.sin(Math.PI*ship.rotation/180)*thrustPower;
}
// move
ship.x += shipMoveX;
ship.y += shipMoveY;
// wrap around screen
if ((shipMoveX > 0) && (ship.x > 470)) {
ship.x -= 490;
}
if ((shipMoveX < 0) && (ship.x < -20)) {
ship.x += 500;
}
if ((shipMoveY > 0) && (ship.y > 320)) {
ship.y -= 340;
}
if ((shipMoveY < 0) && (ship.y < -20)) {
ship.y += 340;
}
}
// remove ship
public function shipHit() {
gameMode = "delay";
ship.gotoAndPlay("explode");
sndExplosion=new explosion_sound();
sndExplosionChannel=sndExplosion.play();
removeAllShieldIcons();
delayTimer = new Timer(2000,1);
delayTimer.addEventListener(TimerEvent.TIMER_COMPLETE,newShip);
delayTimer.start();
removeShipIcon();
shipsLeft--;
}
// turn on shield for 3 seconds
public function startShield(freeShield:Boolean) {
if (shieldsLeft < 1) return; // no shields left
if (shieldOn) return; // shield already on
// turn on shield and set timer to turn off
ship.shield.visible = true;
sndShield=new shield_sound();
sndShieldChannel=sndShield.play();
shieldTimer = new Timer(3000,1);
shieldTimer.addEventListener(TimerEvent.TIMER_COMPLETE,endShield);
shieldTimer.start();
// update shields remaining
if (!freeShield) {
removeShieldIcon();
shieldsLeft--;
}
shieldOn = true;
}
// turn off shield
public function endShield(event:TimerEvent) {
ship.shield.visible = false;
shieldOn = false;
}
// ROCKS
// create a single rock of a specific size
public function newRock(x,y:int, rockType:String) {
trace("newRock fired");
// create appropriate new class
var newRock:MovieClip;
var rockRadius:Number;
if (rockType == "Big") {
newRock = new Rock_Big();
rockRadius = 35;
} else if (rockType == "Medium") {
newRock = new Rock_Medium();
rockRadius = 20;
} else if (rockType == "Small") {
newRock = new Rock_Small();
rockRadius = 10;
}
// choose a random look
newRock.gotoAndStop(Math.ceil(Math.random()*3));
// set start position
newRock.x = x;
newRock.y = y;
// set random movement and rotation
var dx:Number = Math.random()*2.0-1.0;
var dy:Number = Math.random()*2.0-1.0;
var dr:Number = Math.random();
// add to stage and to rocks list
gameObjects.addChild(newRock);
setChildIndex(gameObjects,1); // I added this
rocks.push({rock:newRock, dx:dx, dy:dy, dr:dr, rockType:rockType, rockRadius: rockRadius});
}
// create four rocks
public function nextRockWave(event:TimerEvent) {
rocks = new Array();
newRock(30,30,"Big"); //100 100
newRock(30,290,"Big"); // 100 300
newRock(450,30,"Big"); // 450 100
newRock(450,290,"Big"); // 450 300
gameMode = "play";
}
// animate all rocks
public function moveRocks(timeDiff:uint) {
for(var i:int=rocks.length-1;i>=0;i--) {
// move the rocks
var rockSpeed:Number = rockSpeedStart + rockSpeedIncrease*gameLevel;
rocks[i].rock.x += rocks[i].dx*timeDiff*rockSpeed;
rocks[i].rock.y += rocks[i].dy*timeDiff*rockSpeed;
// rotate rocks
rocks[i].rock.rotation += rocks[i].dr*timeDiff*rockSpeed;
// wrap rocks
if ((rocks[i].dx > 0) && (rocks[i].rock.x > 470)) {
rocks[i].rock.x -= 490;
}
if ((rocks[i].dx < 0) && (rocks[i].rock.x < -20)) {
rocks[i].rock.x += 490;
}
if ((rocks[i].dy > 0) && (rocks[i].rock.y > 325)) {
rocks[i].rock.y -= 345;
}
if ((rocks[i].dy < 0) && (rocks[i].rock.y < -25)) {
rocks[i].rock.y += 345;
}
}
}
public function rockHit(rockNum:uint) {
// create two smaller rocks
sndBubble=new bubble_sound();
sndBubbleChannel=sndBubble.play();
if (rocks[rockNum].rockType == "Big") {
newRock(rocks[rockNum].rock.x,rocks[rockNum].rock.y,"Medium");
newRock(rocks[rockNum].rock.x,rocks[rockNum].rock.y,"Medium");
} else if (rocks[rockNum].rockType == "Medium") {
newRock(rocks[rockNum].rock.x,rocks[rockNum].rock.y,"Small");
newRock(rocks[rockNum].rock.x,rocks[rockNum].rock.y,"Small");
}
// remove original rock
gameObjects.removeChild(rocks[rockNum].rock);
rocks.splice(rockNum,1);
}
// MISSILES
// create a new Missile
public function newMissile() {
// create
var newMissile:Missile = new Missile();
// set direction
newMissile.dx = Math.cos(Math.PI*ship.rotation/180);
newMissile.dy = Math.sin(Math.PI*ship.rotation/180);
// placement
newMissile.x = ship.x + newMissile.dx*shipRadius;
newMissile.y = ship.y + newMissile.dy*shipRadius;
// add to stage and array
gameObjects.addChild(newMissile);
missiles.push(newMissile);
}
// animate missiles
public function moveMissiles(timeDiff:uint) {
for(var i:int=missiles.length-1;i>=0;i--) {
// move
missiles[i].x += missiles[i].dx*missileSpeed*timeDiff;
missiles[i].y += missiles[i].dy*missileSpeed*timeDiff;
// moved off screen
if ((missiles[i].x < 0) || (missiles[i].x > 485) || (missiles[i].y < 0) || (missiles[i].y > 325)) {
gameObjects.removeChild(missiles[i]);
delete missiles[i];
missiles.splice(i,1);
}
}
}
// remove a missile
public function missileHit(missileNum:uint) {
gameObjects.removeChild(missiles[missileNum]);
missiles.splice(missileNum,1);
}
// GAME INTERACTION AND CONTROL
public function moveGameObjects(event:Event) {
// get timer difference and animate
var timePassed:uint = getTimer() - lastTime;
lastTime += timePassed;
moveRocks(timePassed);
if (gameMode != "delay") {
moveShip(timePassed);
}
moveMissiles(timePassed);
checkCollisions();
}
// look for missiles colliding with rocks
public function checkCollisions() {
// loop through rocks
rockloop: for(var j:int=rocks.length-1;j>=0;j--) {
// loop through missiles
missileloop: for(var i:int=missiles.length-1;i>=0;i--) {
// collision detection
if (Point.distance(new Point(rocks[j].rock.x,rocks[j].rock.y),
new Point(missiles[i].x,missiles[i].y))
< rocks[j].rockRadius) {
// remove rock and missile
rockHit(j);
missileHit(i);
// add score
gameScore += 10;
updateScore();
// break out of this loop and continue next one
continue rockloop;
}
}
// check for rock hitting ship
if (gameMode == "play") {
if (shieldOn == false) { // only if shield is off
if (Point.distance(new Point(rocks[j].rock.x,rocks[j].rock.y),
new Point(ship.x,ship.y))
< rocks[j].rockRadius+shipRadius) {
// remove ship and rock
shipHit();
rockHit(j);
}
}
}
}
// all out of rocks, change game mode and trigger more
if ((rocks.length == 0) && (gameMode == "play")) {
gameMode = "betweenlevels";
gameLevel++; // advance a level
levelTextBox.text = "Infection: " + gameLevel;
delayTimer = new Timer(2000,1);
delayTimer.addEventListener(TimerEvent.TIMER_COMPLETE,nextRockWave);
delayTimer.start();
}
}
public function endGame() {
// remove all objects and listeners
removeChild(gameObjects);
removeChild(scoreObjects);
removeChild(gameBackground);
gameObjects = null;
scoreObjects = null;
removeEventListener(Event.ENTER_FRAME,moveGameObjects);
gameMode = "gameOver";
gotoAndStop("gameover");
}
/***** ADD COMMAS TO NUMBERS *******/
function addCommaInNumber (number : Number) : String
{
var integer : String = "" ;
var fraction : String = "" ;
var string : String = number.toString();
var array : Array = string.split(".");
var regex : RegExp = /(\d+)(\d{3})/;
integer = array[0];
while( regex.test(integer) )
{
integer = integer.replace(regex,'$1' + ',' + '$2');
}
if (array[1])
{ fraction = integer.length > 0 ? '.' + array[1] : ''; }
return integer + fraction;
}
}
}

Answer 1

The part of code you thought applied to your problem is incorrect.
A timer can be started along with it's declaration as :
private var myTimer:Timer = new Timer(delay, repeat);
But since you are not initiating the timer at the time of declaration (as seen in you snippet)
// timers
private var delayTimer:Timer;
private var shieldTimer:Timer;
There must be some other function where it would be initiated. Move the action of initiating the timer to whichever place you want to start the timer. For eg : into startspacerocks() function
If that is not the problem, please post the relevant code that applies to your problem.
EDIT:
Well I think your answer lies in the moveGameObjects function.
Try modifying the function as follows:
// GAME INTERACTION AND CONTROL
public function moveGameObjects(event:Event) {
//Current Time
var currentTime:uint = getTimer();
//Initiate lastTime
if(lastTime == 0) lastTime = currentTime;
// get timer difference and animate
var timePassed:uint = currentTime - lastTime;
lastTime += timePassed;
moveRocks(timePassed);
if (gameMode != "delay") {
moveShip(timePassed);
}
moveMissiles(timePassed);
checkCollisions();
}

Answer 2

From the code you've posted, I can't answer your question safely, but you should check, when startSpaceRocks() is called the first time. This should be in the click handler of your start button.
Beside that, your question title does not reflect the problem. There is no problem with a timer at all, there is a problem, when the "timer" is started.