I seem to recall something about pass-by-reference and the Greensock TweenLite class. It's the only thing I can think of that is causing this bit of code to be not working as I intend:
for (var i = 0; i < 10; ++i) {
addItem();
}
public function addItem():MovieClip {
var item:MovieClip = getNewItem();
item.y = item.height / 2;
var newPosY = _origHeight - _items.length * item.height;
_items.push(item);
new TweenLite(item, ITEM_DROP_TIME, { y: newPosY } ); trace(newPosY);
addChild(item);
}
The trace is outputting the values I expect: an incremental sequence where each number is greater than the last (by the height of the item). However, what I see visually is that all the items end up at the same location (as if newPosY were the same for all instances of the tween.)
The only thing that comes to mind is that newPosY is being passed by reference, so each instance of the tween is actually referencing the very same value. Am I missing something? Or do I need some kind of closure to isolate the scope of my tween property's value?
EDIT
Suggesting this question be closed as I guess the answer is "No" and the issue was elsewhere in my code. I doubt that any further exposition of the problem would be relevant to others. Thanks to those who responded!
I think your TweenLite syntax is wrong. Try:
TweenLite.to (item, ITEM_DROP_TIME, { y: newPosY } );
Related
I am using a tileList in ActionScript 3 to display movieclips. However I have the problem that not all reference points of the movieclips are in the correct place. This leads to that these movieclips are shown partly outside of their cell in the tileList.
I have tried to adjust the x and y position of the movieClip before adding it to the tileList, but this did not change anything. Now I have tried to find if it is possible to change the x and y position of an object already in the tileList, but without finding any answers.
I hope that I have made my problem clear.
Thanks in advance!
EDIT:
This is the code I tried:
private function initTileList():void {
for(var i:int = 0; i < _movieClips.length; i++) {
changePos(_movieClips[i]);
tileList.addItem({label: _movieClips[i].name, source: _movieClips[i]});
}
}
private function changePos(mc:MovieClip):void {
if(MovieClip(mc).getRect(mc).x != 0) {
mc.x -= MovieClip(mc).getRect(stateMachineRef).x;
}
if(MovieClip(mc).getRect(mc).y != 0) {
mc.y -= MovieClip(mc).getRect(stateMachineRef).y;
}
}
I do not have any errors, it just doesn't affect the position of the object in the tileList.
Example of how the problem looks.
Hard to say where's the problem without knowing these things:
1. What tileList.AddItem() does exactly;
2. What is stateMachineRef
3. How MovieClips are loaded. If they are loaded from a network, that'll be a whole different story.
By the way, you don't have to cast MovieClip(mc) as mc is already a MovieClip. Also, there is no difference as to when you will correct the coordinates: before or after adding to the tileList. Should work either way.
So, given that information on your problem is not complete, I would just suggest you insure the following steps:
-We assume all tiles are displayed inside a tile container. It can be Stage or a MovieClip or any suitable DisplayObjectContainer, so let's call it just tileContainer from now on.
-We assume all tiles are of the same width and height. If you are not sure, you should check it again.
-We assume that each tile in the tileContainer is displayed at some regular grid coordinates. I.e. it conforms the following code:
for (var pos_y:int = 0; pos_y < GRID_SIZE_Y; pos_y++) {
for (var pos_x:int = 0; pos_x < GRID_SIZE_X; pos_x++) {
var tile:Tile = getNextTile(); // just get a tile from somewhere
tile.source.x = pos_x * TILE_WIDTH; // using your tile structure
tile.source.y = pos_y * TILE_HEIGHT;
tileContainer.addChild(tile.source);
}
}
Now I see your problem that some tiles are created in a way that they have their source movieclip coordinates shifted from (0,0). So they will not align with the grid.
What are you doing seems to be a proper way of aligning them but I don't know exactly what happens in your code so I'll just rewrite it:
function changePos(mc:MovieClip) {
var r:Rectangle = mc.getRect(mc);
mc.x -= r.x; // note you don't need any if's
mc.y -= r.y;
}
And in the above loop just add the changePos() AFTER setting the grid coordinates:
tile.source.x = pos_x * TILE_WIDTH;
tile.source.y = pos_y * TILE_HEIGHT;
changePos(tile.source);
tileContainer.addChild(tile.source);
If you're following all these steps, that's basically all you need and it will work for sure.
If I assign a Vector like
var vec1:Vector.<Number> = new Vector.<Number>(3);
vec1 = (1,2);
the result of vec1.length is 3. Is there any built-in method to return the number of the elements actually present in the vector?
I'm an ActionScript noob so any help would be appreciated.
Well you can solve your problem by creating an empty vector instead of a defining the vector size at the time of its declaration and then you gradually add and remove elements to the vector. In this way you will always get the total number of elements inside the vector when you call vector.length
For example:
var vec1:Vector.<Number> = new Vector.<Number>();
vec1.push(5);
vec1.push(6,7);
vec1.pop();
Then vec1.length would give you 2.
Its been awhile, heres the reference: http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/Vector.html
I believe the .length is the normal way to check its length. If you want to check for "empty elements" you will need to loop through it with a loop.
I don't remmember the exact syntax, but to loop, do something like:
int count = 0;
for (int i = 0; i < vec.length; i++) {
if (vec[i] == ... );
count++;
}
I'm making a simple game and have a Vector full of enemies in order to do hit-checking on them from my "laser" object (it's a space shmup). Every laser loops through the Vector and checks if it's occluding the hit circle. The problem lies in when one laser destroys an enemy, the rest of the lasers try to also check the same Vector, only to go out of bounds since the enemy's already been spliced out and it's changed the size of the Vector.
for each (var enemy:Enemy in enemies){
var distanceX = this.x - enemy.x;
var distanceY = this.y - enemy.y;
var distance = Math.sqrt( (distanceX*distanceX) + (distanceY*distanceY) );
if (distance <= enemy.hitRadius) {
enemy.removeEnemy();
enemies.splice(enemies.indexOf(enemy),enemies.indexOf(enemy));
}
}
How would I go about collecting the index of individual elements in the Vector to be deleted, then only deleting them when every Laser object is finished its checking?
edit: here's my removeEnemy() function from my Enemy class, just in case:
public function removeEnemy(){
removeEventListener(Event.ENTER_FRAME, move);
parent.removeChild(this);
trace("removed Enemy", enemies.indexOf(this));
}
edit edit: I'm also getting a null reference pointer error to "parent" in my removeEnemy() function... but only sometimes. I have a feeling that if I fix one of these two problems, the other will also be fixed but I'm not sure.
I fixed it! The problem was actually in how I used the "splice()" method. Turns out that the second parameter isn't the end index of where to stop splicing, it's the number of elements to be spliced. So when I was trying to splice element 0, I wasn't splicing anything, and when I was trying to splice element 3, I was also splicing 4 and 5. I feel like such a dunce for not reading the API right and wasting a couple hours on this. Thanks to everyone who commented-- you guys helped me rule out what I thought the problem was.
I get this error once in a while for a specific object. For some reason, this issue seems to start when I spawn 2 of this object instead of one. I basically have enemies that drops coins and one enemy drops 2. When I pick them up at the same time I start getting this error.
public function removeCoin(){
removeEventListener(Event.ENTER_FRAME, moveCoin);
if(this.parent){
this.parent.removeChild(this);
}
parentMC.level.spawnedCoins.splice(this, 1);
}
This is the function called by the collision check when there is a collision between the player and the coin. The issue usually starts when I pick up two coins at once from this function.
var dropCoin:Number = Math.random() * 100;
if(dropCoin > 40){
var newCoin1:coin = new coin(parentMC);
var newCoin2:coin = new coin(parentMC);
newCoin1.x = x+7;
newCoin1.y = y;
parentMC.level.levelObjects.addChild(newCoin1);
parentMC.level.spawnedCoins.push(newCoin1);
newCoin2.x = x-7;
newCoin2.y = y;
parentMC.level.levelObjects.addChild(newCoin2);
parentMC.level.spawnedCoins.push(newCoin2);
}
Edited the code.
That error means that the item you're trying to remove from the display list (by calling removechild) either isn't on the display list, or isn't a child of the object your calling removeChild on.
Without analyzing all your code, a quick check can fix your problem likely.
Change you existing chunk of code:
if(this != null){
parentMC.lvl1.levelObjects.removeChild(this);
}
to this:
if(this.parent){
this.parent.removeChild(this);
}
This checks if 'this' has a parent, if so, it removes itself from it's parent.
I think your problem might be:
parentMC.level.spawnedCoins.splice(this, 1);
If spawnedCoins is just an array then splice should take 2 integer args startIndex and deleteCount relevant adobe help page
By passing an object what I think is happening is that it is casting the object to an int, value of '1' (i.e. not null).
What I think you want instead is parentMC.level.spawnedCoins.splice(parentMC.level.spawnedCoin.indexOf(this), 1);
I have noticed a weird behavior of the variables in for loops. It's not really a problem, but it disturbs me a lot.
Actually I've created two loops this way:
for (var i:uint; i<19; i++) SomeFunction (i);
for (var i:uint; i<26; i++) SomeOtherFunction (i);
What I received was a compilation warning:
Warning: Duplicate variable definition.
This warning really surprised me. Nothing like that ever happened to me in other languages.
It seems that the i variable gets into the scope that is higher in the hierarchy and becomes available out of the loop's block. I've also tried to embrace the loop block in a curly brace, but it didn't change anything.
Why does it happen? Is it normal? Is it possible to avoid it? For now I've just set different names for both of the variables, but that's not a real solution I think. I'd really like to use the i-named variable in most of my for-loops.
yes, the loop increment variable is in the scope of the loops parent, not inside the loop itself. This is intentional, for examples like this:
public function getPositionOfValue ( value:String ) : int
{
for ( var i:int = 0; i < someArray; i++ )
{
if (someArray[i] == value )
{
break;
}
}
return i;
}
this allows you to access the value of i once the loop is over. There are lots of cases where this is very useful.
What you should do in the cases where you have multiple loops inside the same scope is var the i outside of the loops:
public function getPositionOfValue ( value:String ) : int
{
var i:int;
for ( i = 0; i < 15; i++ )
{
//do something
}
for ( i = 0; i < 29; i++ )
{
//do something else
}
return i;
}
then you get rid of your warning. The other thing to consider is to name your loop increment variables something more descriptive.
Update: Two other things to consider:
1) you shouldn't use uints except for things like colors and places where Flex expects a uint. They are slower than int's to use. Source]1 Update: it looks like this may no longer be the case in newer versions of the flash player: source
2) when you var a loop increment variable inside of a loop declaration, you want to make sure you set it to the proper initialization value, usually 0. You can get some hard to track down bugs if you dont.
As mentioned here, as3 has global and local scope and that's about it.
It does not do block-level scoping (or for-level either). With hoisting, you can even write to variables before you define them. That's the bit that would do my head in :-)
Early versions of Visual C had this bug, leading to all sorts of wonderful funky macro workarounds but this is not a bug in as3, it's working as designed. You can either restrict your code to having the declaration in the first for only or move the declaration outside all the for statements.
Either way, it's a matter of accepting that the language works one way, even though you may think that's a bad way :-)
Declare the variable i outside the loops to avoid this. As long as you reset it (i=0) you can still use it in all loops.
var i : uint;
for (i=0; i<19; i++) SomeFunction(i);
for (i=0; i<26; i++) SomeOtherFunction(i);