I'm writing a game and it has enemies and bullets. When a bullet hits an enemy, I want to destroy the enemy and the bullet. I'm using the hitTestPoint() method to test if a bullet has hit an enemy. Here's the code in my game loop:
for each(var bullet:Bullet in this.bullets) {
for each(var enemy:Enemy in this.enemies) {
if(enemy.hitTestPoint(bullet.x, bullet.y)) {
trace("hit");
}
}
bullet.update();
}
this.bullets and this.enemies are both arrays containing objects for bullets and enemies. Here's those two classes:
package com {
import flash.display.MovieClip;
import flash.display.Stage;
public class Bullet extends MovieClip {
private var stageRef:Stage;
public var speed:Number = 10;
public function Bullet(stage:Stage) {
this.stageRef = stage;
}
public function update() {
this.x += Math.sin((Math.PI / 180) * (360 - this.rotation)) * this.speed;
this.y += Math.cos((Math.PI / 180) * (360 - this.rotation)) * this.speed;
}
}
}
--
package com {
import flash.display.MovieClip;
import flash.display.Stage;
public class Enemy extends MovieClip {
public var speed:Number = 4;
private var stageRef:Stage;
public function Enemy(stage:Stage) {
this.stageRef = stage;
this.x = this.stageRef.stageWidth / 3;
this.y = this.stageRef.stageHeight / 2;
}
public function update() {
}
}
}
The problem is, hitTestPoint only returns true if both the x and y values of bullet and enemy are the same, rather than if the two movie clips overlap. This leads to bullets going right through enemies but it not registering as a hit. Perhaps I'm missing a bounding box?
Is there a way I can make hitTestPoint return true if the bullet hits the enemy at all rather than only if the bullet and enemy co-ordinates are the same?
Thank you!
You want hitTestObject(), not hitTestPoint()
http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/display/DisplayObject.html#hitTestObject%28%29
Yes, if yours movieclips are too small the frame x will be just right to the object and the next frame it will be pass it, you may want to make a "hitbox" bigger, like doing the movieclip bigger with alpha rectangles.
Related
So I'm currently attempting to make a prototype for a Bullet Hell game and I've run into a bit of a dead end.
So far I can move my player perfectly, the boss moves back and forth as he is supposed to, however the projectiles have some funny behaviour. Basically, when the boss moves left/right, so do the projectiles as if they are stuck to him. They move on the y as they are supposed to, except they stop just short of the player and move no further, so I'm hoping anyone can take a look at my code and give me a hand with what's going on.
Note: Ignore the rotation stuff, that's for later implementation, I was just laying the ground work.
Projectile.as
package
{
import flash.display.Stage;
import flash.display.MovieClip;
import flash.events.Event;
public class Projectile extends MovieClip
{
private var stageRef:Stage;
private var _xVel:Number = 0;
private var _yVel:Number = 0;
private var rotationInRadians = 0;
private const SPEED:Number = 10;
public function Projectile(stageRef:Stage, x:Number, y:Number, rotationInDegrees:Number)
{
this.stageRef = stageRef;
this.x = x;
this.y = y;
this.rotation = rotationInDegrees;
this.rotationInRadians = rotationInDegrees * Math.PI / 180;
}
public function update():void
{
this.y += SPEED;;
if(x > stageRef.stageWidth || x < 0 || y > stageRef.stageHeight || y < 0)
{
//this.removeChild(this); <- Causing a crash, will fix later
}
}
}
}
Boss.as
package
{
import flash.display.MovieClip;
import flash.display.Stage;
import flash.events.Event;
import flash.utils.Timer;
import flash.events.TimerEvent;
public class Boss extends MovieClip
{
private var stageRef:Stage;
private var _vx:Number = 3;
private var _vy:Number = 3;
private var fireTimer:Timer;
private var canFire:Boolean = true;
private var projectile:Projectile;
public var projectileList:Array = [];
public function Boss(stageRef:Stage, X:int, Y:int)
{
this.stageRef = stageRef;
this.x = X;
this.y = Y;
fireTimer = new Timer(300, 1);
fireTimer.addEventListener(TimerEvent.TIMER, fireTimerHandler, false, 0, true);
}
public function update():void
{
this.x += _vx;
if(this.x <= 100 || this.x >= 700)
{
_vx *= -1;
}
fireProjectile();
projectile.update();
}
public function fireProjectile():void
{
if(canFire)
{
projectile = new Projectile(stageRef, this.x / 200 + this._vx, this.y, 90);
addChild(projectile);
canFire = false;
fireTimer.start();
}
}
private function fireTimerHandler(event:TimerEvent) : void
{
canFire = true;
}
}
}
Edit: Current suggestions have been to do the following:
stage.addChild(projectile); and this.parent.addChild(projectile); both which have the projectile firing from the top left corner (0, 0) and not constantly firing from the current center of the Boss.
The other issue, which has been untouched, is the fast that the projectile stops moving after a certain point and remains on the screen.
Another Edit:
After commenting out the code with the timer I have found that the projectile stops moving entirely. The reason why it was stopping after a certain amount of time was due to the timer, when the timer elapsed the projectile stopped and another would fire.
So now I need the projectile to constantly fire and move until it hits the edge of the screen, any ideas?
The problem is you are 'addChild'ing your projectiles to your Boss as opposed the stage (or the same display level as your Boss). When your Boss moves, your projectiles will move relative to him (ie, when he moves sideways, so will they).
When your boss fires a projectile, use a custom event to trigger a fireProjectile method in the Class that is your Boss' display parent. Instantiate your projectiles there and addChild them to the same object to which you addChild your Boss (possibly the stage?).
Alternatively, if you don't want to use a custom event, in your current fireProjectile method change the addChild line to:
this.parent.addChild(projectile);
This will add projectiles to the parent object of your Boss. Although that line seems, slightly, like cheating to me.
I'm new to ActionScript 3.0. I tried a tutorial at http://www.senocular.com/flash/tutorials/as3withmxmlc/ . The demo program animates a ball and allows it to be dragged.
There was a problem with the program as written. When you drag the mouse outside the stage and release the mouse button, the ball wouldn't get the MOUSE_UP event. The code, therefore would never call stopDrag(). I searched stackoverflow for suggestions, and one suggestion was to listen to MOUSE_UP with the stage as well as the ball and add some logic for dealing with it.
I added some code to do this. I also refactored the program as written because it was pretty disorganized. Here's what I have now:
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.geom.Point;
import flash.geom.Rectangle;
public class BallToss extends Sprite {
private var ball:TossableBall;
// mouse position at last call to trackMouseMvt()
private var lastMousePos:Point = new Point();
// delta mouse movement from frame L-1 to frame L, where L is last frame
private var lastDeltaMouse:Point = new Point();
public function BallToss() {
var stageBounds:Rectangle = new Rectangle(0, 0, stage.stageWidth,
stage.stageHeight);
ball = new TossableBall(50, stageBounds);
ball.x = stageBounds.width/2;
ball.y = stageBounds.height/2;
addChild(ball);
ball.addEventListener(MouseEvent.MOUSE_DOWN, grabBall);
// however I order the next two calls to addEventListener(), it seems
// that the ball's MOUSE_UP gets handled before the stage's MOUSE_UP
stage.addEventListener(MouseEvent.MOUSE_UP, handleStageMouseUp);
ball.addEventListener(MouseEvent.MOUSE_UP, releaseBall);
// initialize 'lastMousePos' and set up 'trackMouseMvt' to be called on
// every frame
lastMousePos = new Point(mouseX, mouseY);
ball.addEventListener(Event.ENTER_FRAME, trackMouseMvt);
}
private function grabBall(evt:MouseEvent):void {
trace("in grabBall");
// set ball 'glideVector' to (0,0) so it will stop moving
ball.setGlideVector(new Point(0,0));
ball.startDrag();
}
private function releaseBall(evt:MouseEvent):void {
trace("in releaseBall");
ball.stopDrag();
// set up the ball to glide at the rate of 'lastDeltaMouse'
ball.setGlideVector(lastDeltaMouse);
}
private function trackMouseMvt(evt:Event):void {
var currMouse:Point = new Point(mouseX, mouseY);
lastDeltaMouse = currMouse.subtract(lastMousePos);
lastMousePos = currMouse;
}
private function handleStageMouseUp(evt:Event):void {
trace("in handleStageMouseUp");
ball.stopDrag();
var stageBounds:Rectangle = new Rectangle(0, 0, stage.stageWidth,
stage.stageHeight);
if (ball.x > stageBounds.right - 0.5)
ball.x = stageBounds.right - 0.5;
else if (ball.x < 0)
ball.x = 0;
if (ball.y > stageBounds.bottom - 0.5)
ball.y = stageBounds.bottom - 0.5;
else if (ball.y < 0)
ball.y = 0;
}
}
}
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.Point;
import flash.geom.Rectangle;
class TossableBall extends Sprite {
private var stageBounds:Rectangle;
private var glideVector:Point = new Point();
private var friction:Number = .95;
public function TossableBall(size:Number, stageBoundsIn:Rectangle) {
stageBounds = stageBoundsIn;
graphics.lineStyle(1);
graphics.beginFill(0xFF8000);
graphics.drawCircle(0, 0, size/2);
addEventListener(Event.ENTER_FRAME, glide);
}
public function setGlideVector(glideVectorIn:Point):void {
glideVector = glideVectorIn;
}
private function glide(evt:Event):void {
x += glideVector.x;
y += glideVector.y;
var shapeBounds:Rectangle = getBounds(parent);
if (shapeBounds.left < stageBounds.left) {
glideVector.x = Math.abs(glideVector.x);
} else if (shapeBounds.right > stageBounds.right) {
glideVector.x = -Math.abs(glideVector.x);
}
if (shapeBounds.top < stageBounds.top) {
glideVector.y = Math.abs(glideVector.y);
} else if (shapeBounds.bottom > stageBounds.bottom) {
glideVector.y = -Math.abs(glideVector.y);
}
glideVector.x *= friction;
glideVector.y *= friction;
}
}
I don't like this code very much. The problem comes down to not being able to detect all the cases in one place. I would like to write something like this:
if (..ball and stage both got MOUSE_UP..) {
..handle it..;
else if (..only stage got MOUSE_UP..) {
..handle it..;
}
This logic would let me write more foolproof, simpler case handling and clearer logic. As things stand, there is a lot of complex behavior that emerges from this way of organizing the code.
The event listening model doesn't seem to make this possible. The response to events must happen individually, or must it? Is there a way to detect events that are "in the queue"?
Alternatively, I could avoid using startDrag(), i.e. avoid making the ball Sprite draggable, and have only the stage listen to MOUSE_UP, then handle all the drag logic myself. That would also let me better handle questions like where I want the ball to be positioned when the user drags outside the stage. I wonder if that is better overall.
To track object being dragged this works good for me:
ball.addEventListener(MouseEvent.MOUSE_DOWN, onBallMouseDown)
var _stage:Stage;
private function onBallMouseDown(e:MouseEvent):void
{
_stage = stage;
stage.addEventListener(MouseEvent.MOUSE_UP, onStageMouseUp)
stage.addEventListener(MouseEvent.MOUSE_MOVE, onStageMouseMove)
ball.startDrag();
}
private function onStageMouseMove(e:MouseEvent):void
{
// track ball coordinates
}
private function onStageMouseUp(e:MouseEvent):void
{
ball.stopDrag();
_stage.removeEventListener(MouseEvent.MOUSE_UP, onStageMouseUp)
_stage.removeEventListener(MouseEvent.MOUSE_MOVE, onStageMouseMove)
}
What about that, after years of Flash programming only now have I discovered the joys of MouseEvent.RELEASE_OUTSIDE. No more ugly hacks needed.
I am a beginner with AS3 and I am trying to make a basic Player vs CPU pong game(using a tutorial as reference). I apologize if this sounds stupid or obvious. I have a document class and individual classes for Ball, Player and CPU. My problem is that I don't know how to make CPU class use the co-ordinates of the movie clip ball on the stage so that it can move with respect to the ball as required to form the AI. The tutorial I have been referring has all the code for ball, player and cpu in the document class only but I have written code for everything in their respective classes.
The tutorial link http://as3gametuts.com/2011/03/19/pong-1/
My version of code. Currently the ball is bouncing off the walls but HitTest has not been applied to anything. The player paddle is moving with the arrow keys. No warnings or errors are being displayed.
Main
public class Main extends MovieClip
{
public function Main()
{
this.addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
}
private function onAddedToStage(e:Event):void
{
removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
trace("Initialized");
}
}
Ball
public class Ball extends MovieClip
{
public var ballSpeedX:int = 5;
public var ballSpeedY:int = 6;
public function Ball()
{
this.addEventListener(Event.ADDED_TO_STAGE, onAddedToStage)
}
public function onAddedToStage(e:Event):void
{
removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage)
this.x = stage.stageWidth / 2;
this.y = stage.stageHeight / 2;
this.addEventListener(Event.ENTER_FRAME, loop)
}
public function loop(e:Event):void
{
this.y += ballSpeedY;
this.x += ballSpeedX;
if ((this.y <= 0 + this.height/2) || (this.y >= stage.stageHeight - this.height/2))
{
ballSpeedY *= -1;
}
else if ((this.x <= 0 + this.width/2) || (this.x >= stage.stageWidth - this.width/2))
{
ballSpeedX *= -1;
}
}
}
TheCpu
public class TheCpu extends MovieClip
{
public var cpu:TheCpu;
public var ball:Ball;
private var vx:Number = 5;
public function TheCpu()
{
this.addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
}
private function onAddedToStage(e:Event):void
{
removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
this.x = 240;
this.y = 10;
this.addEventListener(Event.ENTER_FRAME, loop);
}
private function loop(e:Event):void
{
/*if (this.x < ball.x - 10)
{
this.x += vx;
}
else if (this.x > ball.x + 10)
{
this.x -= vx;
}*/
}
}
I added this to my main class
private function onAddedToStage(e:Event):void
{
removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
trace("It's Alive!");
addBall();
addCPU();
}
public function addBall():void
{
var ball:MovieClip = stage.getChildByName("ball") as MovieClip
stage.addChild(ball);
}
public function addCPU():void
{
var cpu:MovieClip = stage.getChildByName("cpu") as MovieClip
stage.addChild(cpu);
}
}
but now it is giving error
TypeError: Error #2007: Parameter child must be non-null.
at flash.display::DisplayObjectContainer/addChild()
at flash.display::Stage/addChild()
at src::Main/addBall()
at src::Main/onAddedToStage()
and if I use
var ball:Ball = new Ball();
var cpu:TheCpu = new TheCpu();
I get
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at src::TheCpu()
at src::Main/addCPU()
at src::Main/onAddedToStage()
I think I am being really dumb now.
As a simpler solution.
Basically when you create the ball you could pass the instance of the ball to the CPU so that the CPU can just check where the ball is on each update/enter frame. Something like this:
var ball:Ball = new Ball();
var cpu:CPU = new CPU(ball);
I think ideally you would have an update loop that just tells each part to update itself in sequence and passes along any important information between the objects so they can update themselves appropriately (and the main update loop can track things like ball out of region/point scored etc.)
EDIT
If I understand you correctly you've placed symbols on the stage in Flash and have assigned these code blocks to each of them. So your issue is you don't know how to reference each of the instances. You could use this method to retrieve the instances you put on the stage by naming them and referring to them by name:
How do I access a movieClip on the stage using as3 class?
Alternatively you could create the instances in the Main class in the added to Stage handler by creating instances as shown in the code block above then calling:
stage.addChild(cpu);
stage.addChild(ball);
Just be sure to use the MovieClip symbol name from the library in place of CPU and Ball.
In your commented-out code in the TheCpu class, you put "ball.y" when I think you meant "ball.x".
I'm making a flash game for my course at college, I have been following a tutorial but been spinning it off for my own sake. One wall I hit is that when I fire a bullet, it will only fire to the right, with a little movement up or down, I have been trying to fix it for a while but nothing is happening and nothing works.
package {
import flash.display.MovieClip;
import flash.events.Event;
import flash.events.MouseEvent;
public class Wizard extends MovieClip {
private var dx:Number;
private var dy:Number;
private var Bulletspeed:int;
public var Angle:Number;
public var newAngle:Number;
var shotCoolDown:int;
const MAX_COOLDOWN=20;
public function Wizard() {
//constructor
//Shot cool down
shotCoolDown=MAX_COOLDOWN;
addEventListener(Event.ENTER_FRAME, update);
//set up an event listener for when the turret is added to stage
addEventListener(Event.ADDED_TO_STAGE, initialise);
}
function initialise(e:Event) {
//reduce shot cool down by one
shotCoolDown=shotCoolDown-1;
//add a click listener to the stage
stage.addEventListener(MouseEvent.CLICK, fire);
}
function fire(m:MouseEvent) {
//Able to shoot
if (shotCoolDown<=0) {
//resets cool down
shotCoolDown=MAX_COOLDOWN;
//spawn bullet
var B = new Bullet();
//set position and rotation of the bullet
B.rotation=rotation;
B.x=x;
B.y=y;
//add the bullet the the wizard
parent.addChild(B);
}
}
function update():void {
//Shot cool down
shotCoolDown--;
//Make the Wizard face the mouse
if (parent!=null) {
dx=stage.mouseX-this.x;
dy=stage.mouseY-this.y;
Math.abs(dx);
Math.abs(dy);
var Angle=Math.atan2(dy,dx);
var newAngle = Angle * (180 / Math.PI);
if ((0 < newAngle) && (newAngle <= 90)) {
gotoAndPlay("Right");
} else if ((90 < newAngle) && (newAngle <= 180)) {
gotoAndPlay("Down");
} else if ((-180 < newAngle) && (newAngle <= -90)) {
gotoAndPlay("Left");
} else if ((-90 < newAngle) && (newAngle <= 0)) {
gotoAndPlay("Up");
}
this.rotation=Angle;
}
}
}
}
That's the code for my player class, with things such as bullets firing and what not. I think I know the problem, I need to link it to the rest of the Wizard update. But I don't know how, here is my bullet class if needed.
package {
import flash.display.Sprite;
import flash.events.Event;
public class Bullet extends Sprite {
private var speed:int;
private var myCharacter:Wizard;
public function Bullet() {
//constructor
speed = 10;
addEventListener(Event.ENTER_FRAME, update);
}
function update (e:Event) {
//Move in the direction the bullet is facing
x=x+Math.cos(rotation/180*Math.PI)*speed;
y=y+Math.sin(rotation/180*Math.PI)*speed;
//Clears bullet once it leaves the stage
if (x<0 || x>500 || y<0 || y>500) {
//removes the update listner
removeEventListener(Event.ENTER_FRAME, update);
parent.removeChild(this);
}
}
}
}
You're setting the Wizard's rotation to Angle, which is in radians; the rotation is then passed on to the Bullet, which expects its rotation to be in degrees. It's probably better to set this.rotation=newAngle; at the end of update(), as the UIComponent class expects that value in degrees and uses it for rotating its drawing.
I have a class that I use to display text on stage, with some number effects. It works pretty well, but when I chain it like this
public function onAdd(e:Event) {
//stuff
addChild(new messager("Welcome."));
addChild(new messager("WASD to move, mouse to shoot."));
addChild(new messager("Kill zombies for XP and collect ammo boxes.",waveOne));
}
public function waveOne(){
addChild(new messager("Good luck and have fun.",newWave));
}
The text (Good luck and have fun) is not displayed, but newWave is called. The reason why I don't call waveOne in onAdd is so that it doesn't happen too quick - my class just throws the text at the user once every 50 frames (which is intended, for later when you kill enemies and the text needs to catch up).
Here is my class (with the effects removed):
package {
import flash.display.MovieClip;
import flash.events.*;
import flash.utils.Timer;
public class Messager extends MovieClip{
var actualText:String;
var callback:Function;
var upTo:int = 0;
static var waitingFor:int = 0;
public function Messager(text:String,callback:Function=null) {
this.callback = callback;
actualText = text;
x = 320 - actualText.length * 6.5;
y = 0 - waitingFor * 60;
addEventListener(Event.ENTER_FRAME, onEnterFrame);
waitingFor++;
}
public function onEnterFrame(e:Event) {
y+= 1;
if(y > 60){
waitingFor--;
}
if(y > 200){
alpha -= 0.03;
if(alpha <= 0){
if(callback != null){
callback();
}
removeEventListener(Event.ENTER_FRAME, onEntFrm);
this.parent.removeChild(this);
}
}
}
}
It is set to linkage with a movieclip that has a textfield.
Thanks for any help.
y = 0 - waitingFor * 60; Maybe y of the last Mesager is a big negative number? Have you tried to trace waitingFor?