I need to create a single SWF with no external files, so I'm trying to add an internal preloader to my Flash project which has [embed] assets. I know [embed] causes problems with preloaders because it puts the assets on frame 1. I have tried the solutions recommended in these posts, where you set the document class to your preloader class:
Preloader for SWF with embed bytearray
How to create Preloader in AS3
I can get it to work, but ONLY if I comment out any lines of code that involve the stage, otherwise I get an "Error #1009: Cannot access a property or method of a null object reference." Those lines are essential though, so does anyone know how to fix those errors with the stage?
You haven't posted your code or your fla, so all I can do is share what works for me.
First, I wouldn't use Embed. Instead, use a swc. I have found that Embed can be unreliable as far as actually getting the entire asset in there (at least when publishing with Flash Builder + Flash Pro, which is my workflow).
Once you have your assets in a swc, try the following steps:
Set your export frame to Frame 10 (or any frame other than 1--I like frame 10 because then you can read the label that says "Preloader")
Put your actual content on frame 11. You can structure this a lot of ways. Since I program to Interfaces, I give whatever is on frame 11 an instance name and then use a setter to determine that my "first thing" has been placed on stage. I can get away with this because my main Document Class just knows the definition of the Interface, not the full implementation of the Class, so the Class does not need to load for the main Document Class to work. You probably aren't truly using the timeline and probably didn't program to interfaces, so you'll probably just set the base class of the symbol that's on frame 11 to the main logic of whatever you're trying to do.
Put your preloader graphics in Frame 1. I'm not sure why your stage references are so important. I, personally, don't use any logic in the preloader. Instead, I use a spinner that spans frames 1-10 (plus the word "Loading...". The spinner just spins while the classes load. The embed frame acts as a temporary "stop" that just holds the timeline back until those classes have been loaded. Once the classes have been loaded, the timeline will act like you called play() on it. So it really can be that simple. If you need it to be more complicated, give one of your preloader graphics an instance name and set up a getter/setter pair for it, then use the setter to trigger your logic that accesses the stage. You are pretty much guaranteed to have a valid stage at that point.
Word of warning: if you did make use of the timelime, you will get strange results if you try to jump to a frame that isn't loaded yet, so make sure to check to see if a given frame is loaded if it's near the end of your main timeline and your main timeline is heavy with assets before calling goToAndPlay() or goToAndStop().
Some references that might help you further:
Preloaders vs as 3 (I'd recommend you read the entire series this is part of. This is an amazing series I wish I'd found 3 years ago)
Solving the Frame 2 Problem Presentation and code
Combining the Timeline with OOP The example code for that is here (long story)
Related
first of all I want to tell that I know there are hundreds of similar questions, but most of them are for projects/games which are built for "on stage development".
I'm using pure as3 approach to develop games. I don't use*main timeline and my project has only 1 frame*.
On my main class's constructor, I only add preloader to the stage.
But still my preloader is seen only when the game is completely loaded.
My question is simple: "Why?" and "How can I fix this?"
-When I try to "uncheck" export as3 on frame 1, flash gives error.(because some of my classes are imported on the main class.)
-Even if I create second frame and put every contents of the game except preloader, the problem is still unsolved.
Thank you very much for spending your time to read this and help me.
-Ozan
To make the preloader, you either need two SWFs or at least two frames. Even FlashDevelop has an ability to use two frames, for this the directive [frame factoryClass="ClassName"] is used in main AS file before public class Main. This is the core limitation of Flash player, that is, it first loads the first frame, and only then it can display that frame. Since you've said you have only one frame, then your game has to be loaded 100% (1/1 frames) before you will see a thing.
There's more - if you are referencing a certain class on frame 1 via its class name, the class with all its dependencies is embedded in the same frame (the first), so you're screwed again. To bypass this, execute stepos 10 through 14 from this instruction to set the frame for classes to be 2 (replace 10 for 2 while executing the instruction), clear "export in the first frame" for all classes except your preloader, and add an instance of game's main class to keyframe 2. Then in preloader code perform proper cleanup and do gotoAndStop(2).
I have been writing a game in timeline code. I want the different frames (rooms) in the game to be able to share information between each other. Of course, timeline code is limited to the frame it is written in.
After doing quite a bit of reading ("Foundation Game Design with Flash" and a number of articles, tutorials, forums etc) I decided to employ a document class. This did not work either. It seems it only works for frame one but not the rest of the frames (I have four).
How can I have frame four respond to something that happpened in frame one? For example, if the player achieves something in frame one, I want a movie clip in frame four to be visible.
If You are writing your code on the timeline, My suggestion would be to create two layers in the timeline, one for 'frame-actions' - in this layer you insert the code specific to a single frame (will work when the movieclip is stopped on that particular frame).. And also create one more layer called global-actions (for the entire timeline). Only the first frame will be a key frame and there should be empty frames till the end of the timeline.
In this layer actions write the code that you want to access from any keyframe in the same timeline.
If you define a variable in the actions which are written for the whole timeline (global-actions) then that will be available on all the frames.
Now if you want to go to a different frame based on some action, just write some functions in the layer which contains global actions and call that particular function through the frame actions. To go to a different frame use the 'gotoAndStop(frameNumber)' function of flash.
I want to tell you that while it will work, I would not recommend using it in this way.
HTH.
You can use static variables - these are variables which are linked to a class, rather than an instance of it.
Suppose your document class was called Document.as, and you wanted a variable, playerLives, to be visible from any part of the program.
Declare it inside Document.as:
public static var playerLives:int = 3;
You can then reference this directly from anywhere else in your code with:
Document.playerLives
(note that the variable is a member of the class itself, not an instance of it).
You could use a dedicated Statics class to hold these variables if you want to keep your document neat, or attach them to the relevant classes (eg Player.lives)
I've not used timeline/frames for some years but I believe this is how I used to do it!
NB Statics will be fine for your purposes but they are, in some ways, an equivalent to the _global variable in AS2 (at least, they can be used in the same manner) - many would not approve of their use, or over-use, as they are freely accessible from anywhere in your program (thus anathema to the OO concept of encapsulation), but personally I try not to worry about it in small cases - the most important thing to know about the rules of any design pattern is when they can be broken!
They are also slightly slower to access than instance members, but you won't notice this unless you are constantly accessing/changing them (making things like player velocity, which will need to be referenced/changed every frame, static, is not a good idea).
Hope this helps.
You may find the simplest way to link everything with the document class is to move your four frames into a movieclip together and have that on the first frame, then interact with that movieclip.
E.g. in the document class, where the movieclip instance on the timeline is called 'game'.
game.gotoAndStop(4);
game.objectToDisplay.visible = true;
If you encounter reference errors in the IDE then you can avoid these by using [] notation to refer to the properties of game, e.g. game["objectToDisplay"].visible = true;
Note that it's not really best practice to do this, but it will at least help you to finish that first game which is really more important at this stage in your learning. Afterwards, if you want to learn more then I'd recommend "The Essential Guide to Flash Games" by Jeff Fulton from 8bitrocket.com - it will teach you how to use the document class effectively.
I am currently working on a rather large, UI-heavy Flash game. Our team has been working on this for about 9 months now. None of us had any previous experience with Flash, so we have continually improved our workflows during this time. However, we still feel that what we are doing now is not optimal, especially the interface between coders and artists, so I am wondering how other teams are working.
The ideal workflow should satisfy the following requirements:
1. Reused UI elements are defined only once
This means, if we want to change a font or a button style, we do not want to go trough all of our menus and change them manually. We want them defined in one central place and only referenced from there. Bonus points if the assets are shared not only at edit time but also at runtime, i.e. they are downloaded only once.
2. Everything is loaded on demand
Currently, we have two different loading steps: First, we load the menu libraries. When this is done, the players can already interact with all the menus. Then, we start loading the actual gameplay data. The initial loading time is still too long, though, and causes us to lose many potential players. What we really want to do is to load only the bare minimum required for the main menu and then load everything else only when the player tries to actually open the respective menus. Zuma Blitz does this really well.
3. Artists can perform minor changes without help from coders
If a menu should be re-designed without changing the actual functionality, it should be possible for artists to do that on their own in Flash CS6. This requires a clear interface between art and code, and it should also be possible for artists to test and debug their changes before sending them to the coders.
-
Our current workflow looks like this: The artist build the screens as MovieClips in Flash CS6 and export them as SWFs. On the code side, load the MovieClips from the screen SWFs and use them as the View classes in our PureMVC-based system. The Mediators access the elements like text fields in the Views by their instance names.
This is error-prone because there is no central place to define the interface (i.e. the instance names). A lot of communication overhead between coder and artist is required. Also, it creates a dependency between the code and the internal structure of the movieclip. The artists cannot attach the text field to a different sub-movieclip when they want to apply some effects to it.
We are experimenting with an event-based interface that requires the artist to add a few lines of code to the movieclip. This is less error-prone and interdependent than before, but it still does not completely satisfy (3) unless we write additional tools for testing and debugging. This must be a common problem and I can hardly imagine that there is no easier way.
For (2), we also started building a home-brewed solution but again, this is such a common task, there has to be something out there already that we can use.
So, how do experienced Flash developers manage such large projects?
I have some thoughts, but they are based on my coding style, which is unique to me.
1. Reused UI elements are defined only once
Depending on what you're reusing, this can be as simple as defining a library symbol and just using it. Fonts can be replaced without digging with a search and replace, and you can also simply swap out the font in the Font Embedding menu.
For sharing across xfl's, you can use a Flash Pro Project. Keep in mind that there's a certain amount of time overhead involved in this (files will want to update when you open them or save them, Flash crashes more with Projects, and it can be a bad idea to try to work on two files from the same project at once).
Some people use swcs, but doing so requires that you instantiate things in it in code, which might not work for your workflow. I use them for audio only, and I find that the objects in it have to be compiled on or before the frame you designate as the AS compile frame, or the sound can't be properly instantiated. I suspect this is going to be the case for anything instantiated from a swc.
2. Everything is loaded on demand
One of the best-kept secrets of Flash is that this is trivially easy to accomplish using the timeline and educated use of the complier. Here's how it works:
If your ActionScript compile frame is a frame greater than 1, then here is how things will compile:
Before Frame 1:
Any visual assets and embedded sounds used on frame 1
Your main Document Class, plus any Classes directly referenced from the Document Class (which is a good reason to code to Interfaces)
Before your AS compile frame (N):
Your AS Classes (the code, not necessarily the visual/audio assets)
The visual and audio assets for any library symbols set to Export for AS in frame N (even if they are not used in the swf)
Before the frame where the asset is first used on the timeline:
The visual/audio assets in all library symbols where Export for AS in frame N is not checked.
If you put a spinner loading graphic on frame 1 and you have selected frame 10 as your export frame, then if you just let the movie play until it hits frame 10, here is how it will load:
If you have any heavy assets in your spinner or directly referenced in your main Document Class, users will see a blank screen while this stuff downloads
The spinner will become visible and spin
Once your AS Classes have loaded, along with the Library Symbols set to Export in Frame 10 and the assets that are actually on Frame 10, you'll see those assets, and everything you need to use them will be ready.
The rest of the swf will continue to load in the background, updating framesLoaded.
I actually use a combination of a setter for the object that's on frame 10, plus an ENTER_FRAME handler to check to see if we're on frame 10 yet. There are certain things that I have to do that are easier based on one and others that work better to do the other way.
3. Artists can perform minor changes without help from coders
If the code is all in the Base Class for the library symbol, artists don't need to understand it, as long as they don't remove or change a needed instance name. I try to minimize dependence on instance names by watching ADDED_TO_STAGE (capture phase) and watching for Display Objects by type. Once I have a reference to an object of the appropriate type, it's easy enough to watch for REMOVED_FROM_STAGE on that object to dereference it. This is similar to how frameworks such as RobotLegs and Swiz work.
Further, I use a concept I call "Semantic Flash," where I do a lot based on labels. I have a base Class, FrameLabelCip, which has built-in nextLabel() and previousLabel() functionality, as well as dispatching FRAME_LABEL_CONSTRUCTED events. It's really easy to go from storyboard event name to Flash label name and just build out the graphics bang-bang-bang.
I make heavy use of Graphic Symbols for synchronizing graphics across multiple labels (for example, bulleted lists), instead of relying on code. This animator's trick makes these things both robust and approachable to less-technical teammates.
I created an AS3 preloader, and placed the code for that on frame one.
I then made a symbol, and placed it in the library. It was set to NOT export on frame 1, and the fla's settings had all classes exported on frame two. There were no references to the object until frame two.
Then, flash crashed whenever I compiled without the "Export in frame one" box checked.
To fix this, a friend suggested I start my game logic on frame 3, so it will have properly loaded frame 2. That seemed to work fine, the class was instantiating properly.
Then, it turned out that it was not loading the movieclip, only instantiating the class. Again, this could be fixed by exporting in frame 1, but I really cannot afford to do that.
The same friend suggested I place an instance of the symbol on the stage on frame 3, and perform game logic on frame 4. They said this would initialize the movieclip properly.
However, this was not the case. How can I load the entire symbol, graphics and all, without exporting to frame 1? This single symbol will contain probably 10-20 MB of graphics, so it needs to be preloaded.
Thanks for the help!
EDIT: To make a long story short, all I need is some way to load a movieclip so it can be used and visible and everything.
EDIT: Is there any way to force-load a movieclip via AS3?
Hard to figure out from descriptions.
If you make a new .fla file, paste your large(10-20MB) clip on frame 2,
set your export frame as 2, then try to preload from frame 1 and access the large clip's content in frame 2, do you get the same error ?
say you have this in frame 1:
stop();
this.loaderInfo.addEventListener(Event.COMPLETE, onComplete);
function onComplete(event:Event):void{
gotoAndStop(2);
}
and in frame 2:
trace(myLargeClip);//where myLargeClip would be your 10-20MB clip
It should be ok, otherwise, in case tracing your large clip returns null, you might want to try to invalidate the stage:
on frame 2:
stage.addEventListener(Event.RENDER,onRender);
stage.invalidate();
function onRender(event:Event):void{
trace(myLargeClip);
}
Basically what I'm suggesting is:
Isolate the problem. See if your large clip is causing problems in a similar, but simplified scenario and why, then once you got a fix use it in your main fla.
Try the stage invalidation, although, since I don't fully understand your setup, it's just a wild guess.
HTH,
George
I am using the frames in the timeline of a .swf as pages in a flash app. The user can advance to the next page by clicking a button that takes her to the next frame. Similarly, it is possible to navigate to the previous frame/page as well.
Most of the content is placed on the stage (i.e. created by dragging an instance of a library symbol to the stage) but properties of those instances, such as .visible might be changed via actionscript. Also, some objects are loaded from external flash files and displayed programmatically with addChild / addChildAt.
The problem is, if I am on Frame N+1 and there is an object displayed on the stage programmatically (i.e. with addChild, not by having it placed on the stage) and navigate to Frame N where there is an object that is placed on the stage (i.e. dragged from the library),
then the instance of that object is undefined/null and throws an error if I try to set its properties (like .visible).
The error does not occur if I am moving to the NEXT frame, only if I am moving to the PREVIOUS one. Therefore I assume that some kind of initialization is not getting called while going one frame back.
I was also thinking that the objects would just not "live" to the next timeframe, that is, their value would be lost and re-initialized because of scope, but if there is no dynamically created object on the stage, I can navigate back and forth just fine.
Is there a way to ensure that the objects created on the stage do not disappear while navigating back to the previous frame?
The first, and more useful, part of the answer is this: timeline keyframes and scripts can give conflicting information about display objects - whether they should exist, where they should be, and so on. For example, when you add an item by playing into its frame, and then delete it with script, and then play into its frame again. When this happens, there's no unambiguously correct thing for Flash to do, so it tends to be unpredictable. I believe what generally happens is that once you fiddle with a given object via script, it's considered to no longer pay attention to the timeline - but your mileage will vary.
Having said that, the reason things are different when you play backwards is the second and more arcane part of the answer. Internally Flash functions differently when seeking forward and backwards on the timeline. Flash internally treats keyframes as changes to be applied in the forward direction, so as you play forward, it applies those changes in sequence. When you move backwards, however, from frame N+X to frame N, it doesn't scan through the intervening X frames reversing those changes - it jumps back to frame 1 and fast-forwards along to frame N. Normally, it amounts to the same thing and you don't need to worry about it, but when you get into the twitchy area where scripts and the timeline have a different idea of what should be on the stage, you're liable to see things behave differently depending on which way you jump (as you are now).
The super-short version is, for things to work predictably, try to ensure that any given object gets added, updated, and removed the same way - either all via script, or all via the timeline. When that seems impossible, fiddle with your content structure - usually, the best solution is to change your object into two nested ones, so that the things you want to do with script occur one level higher or lower than the things you want to do with the timeline.
I'm not sure I got your question right, but as3 does not instantiate elements on the timeline as soon as you gotoAndSomething, but later that frame.
That is, you can't
this.gotoAndPlay(10)
this.elementOnTimelineFrame10.DoSomething()
without errors.
I remember using this chunk of code in the past to work around this problem. It uses the Stage.Invalidate() function to wait for an Event.RENDER before trying to access and children, more info (although vague as hell) is here
private function init():void
{
stage.addEventListener(Event.RENDER, stage_renderHandler);
}
private function stage_renderHandler(evt:Event):void
{
// Run your code here
updateChildren();
}
private function enterFrameHandler(evt:Event):void
{
// triggers the RENDER event
stage.invalidate();
}
This also might me very costly (performance wise). I would strongly advise against dynamically adding/removing objects to an existing timeline, is there any way in which you can place an empty Sprite above the timeline animation and use that for all your dynamic content?
Hope this helps