My question is, in a flash game I use different frames for levels. And I am confused on how functions work for this. My first frame works fine but I need help with using functions on other frames and keeping functions specific to one frame. Any help is appreciated, just a quick simple explanation
You cannot associate a function with a specific frame.
When you execute code on a frame, what actually happens is the MovieClip containing that frame will call a function called addFrameScript(), passing to it a representation of the code you write on the frame.
This means:
Until you visit a frame that defines a function, you cannot call said function.
Once you have visited a frame that defines a function, that function is attached to the parent MovieClip, and you are able to call the function at any point in the timeline that is earlier or later.
If you try to define a new function with the same name on a different frame, you will get a 1021: Duplicate function definition error.
Instead of making a new function for every frame or level, you should make a single function that is able to handle different information that is representative of a level, e.g.
function loadLevel(level:int):void
{
// Do stuff with the value of level.
// For example, this function might look at a data source that maps
// the level numbers to some level data representing tile placement.
}
This could be defined on the first frame, then on each subsequent frame:
loadLevel(1); // Frame 2
loadLevel(2); // Frame 3
// ...etc
All of this of course is not ideal and could be done better avoiding the timeline and instead using to OOP paradigm that AS3 provides.
I have found using multiple levels within the same scene causes no end to headaches for me.
I'm no expert & i'm sure its possible to do so in many cases and I have seen some great games created using 1 frame 1 scene & all code in an external .as.
However I find it much easier myself to just use 1 frame per level and put each level in a different Scene.
Related
I'm initializing symbols in my timeline, and trying to access the variables within those symbols, but they return 0 or undefined even though I set the variables in the symbol's timeline. For some reason the variables haven't been set yet, though the main timeline can see that they exist. How do I make the program wait until the variables have been set?
Best practice to work with classes, not coding in timeline and frames of MovieClip.
I assume you have MovieClip from designer and you want inject some logic to the specific frame. There are many options.
Events
You can trigger event in the specific frame, and you work in normal way (with classes and class members).
//Frame code
import flash.events.Event;
this.dispatchEvent(new Event("IntroDidFinish", true, true));
stop();
//Somewhere in class
myContainer.addEventListener("IntroDidFinish", onIntroFinish, false, 0, true);
function onIntroFinish(e: Event):void{
//Do your stuff
}
Events help you decouple logic from the design(predefined complex MovieClip, etc.)
Waiting for initialisation
As MovieClip reaches some frame, you should wait extra time for initialisation. Thats why 99.9% of AS3 developers don't like MovieClip as holder for any critical data or logic. It means if you call myMovieClip.goToAndStop(8); you can't get myMovieClip.someValue declared in 8 frame after goTo operation. If you still want to go with such approach, easiest solution for you will be Event.ENTER_FRAME, after goTo subscribe for ENTER_FRAME event, for only one update, and do your work ;)
I'm new to programming and I've been checking a lot of game coding tutorials. I've noticed that on most of them they use custom events to trigger methods instead of calling a method directly.
What's the reasoning behind this practice? Why aren't they just calling the method?
For example:
We have two objects: A and B. A has method A.methodA() that B needs to use when X condition is triggered.
Why implement:
B dispatches an event to A that tells A to run A.methodA()
Instead of:
B uses A.methodA()
The main reason is separation of interests. When using events, class A doesn't need to know about the existence of class B (and vice versa).
Some benefits to this are:
Much easier unit testing (you can test Class A without class B)
Less chance of breaking your code when you change class A or B
Less references to other classes in your code, which reduces the potential for memory leaks
Cleaner code
More flexible/reusable code (a bunch of other classes could all listen/respond to the event without any additional code in the your dispatcher)
Typically in bigger applications using events will help abstract everything. When you have 15+ classes and they're all ditpatching events to a controller, it's a lot easier to figure out what's going on than reading through all different parts of the code to trace functions. Using callbacks begins to create spaghetti code.
However, direct function calls are going to be executed faster than events.
Personally, I use custom events simply for the ease of use. I can have one class dispatch an event when something happens (say an animation finishes or an error occurs in a download) and any number of other classes run any number of other functions based on that event. In addition, I code for reusability. The goal of each class is complete independence so that it can run in any project without needing other packages. So rather than have one class call a method of another class, I dispatch an event from the first class that the second class listens for and then run that method. Then when I need that first class for another project, I can just copy/paste it without having to modify it and without losing any functionality.
EDIT:
Also, it's worth noting that sometimes people do what you describe to get around having to pass in event arguments.
Say you have a button on the stage and you need to be able to click it, but you also need to be able to manually call that method. Some people don't realize you can pass in a null event and have only the single method. Or you can set it as a null default argument, see below:
private function onClickHandler( e:MouseEvent = null ):void{
//as long as you never reference "e" within this method, this method can be used both for MouseEvent listeners and manually calling it elsewhere in the code
}
That technique can help avoid having an event handler that only calls another method and nothing else. At this point in my programming, every single AS3 event handler I write sets the event argument to null by default. It just makes things easier later on.
You might want to read this.
And also note using the callback method allows you to pass parameters to it directly and not via a custom event model.
I built my own, very simplified, events dispatcher system. AS Event model is very powerful, but in 99% of situations you don't need that power. A simple callback with parameters fired as an event is more than enough. You can still retain the versatility from an event model, but don't need to write too many lines of code for, let's say, a simple button.
I can setup a simple event like this:
Buttonizer.autoButton(_buttQuit, this, "onPress");
public function onPressQuit(c:Sprite) {
// Execution goes here
}
You can build your own event model, it will make life simpler, and your code much more concise.
I have an object (MovieClip) on stage at some frame, and at the next frame, even though the object is visually removed, it is still there (it has an internal function that generates something on stage periodically, and the stage objects are being generated). I know I can simply stop the action while leaving the frame, but the object will eat up memory and maybe even CPU time for some background actions (and this is a AIR to iOS project so I care about memory and performance). How can I get rid of the object entirely? I expect everything to be removed when I navigate to another frame if it's a designer-placed object (if the object is not generated by ActionScript) and this is the case, but it only gets visually removed.
Thanks,
Can.
Just null your object reference and it's listeners.
...
myMovieClip.removeListeners();//class function
myMovieClip.parent.removeChild(myMovieClip);
myMovieclip = null;
...
I'm working on a portfolio suggestion application in Flash, which consists of two views: ask user for 3 to 4 points of information, and display recommendations based on that information.
The first view is going swimmingly, as all I need are the graphics to be created. However, I'm having trouble understanding how a AS3 variable can be seen across keyframes when it was declared and initialized on the first frame.
The only multi-view app I've done is a Restaurant Guide flash app that was described in Adobe Flash CS5 Classroom in a Book. In that example, the only AS function on four of the views
was a stop() function.
If I were to do the same in this app, and declare the variables as global in the first frame, will they be accessible throughout?
CLARIFICATION
Two comments have said that my question is unclear, so I hope this makes my question more understandable. I want to know how, if I gather all the user information on Frame 1 and then switch to a view on Frame 15, to access those variables on Frame 1.
This isn't really the way you're supposed to work in AS3. Each view should be an object in your library with an associated class. Your document should also have a class associated with it, and it is here that you would hold your common data. The document class would instantiate each view as it is required and pass in the relevant variables.
That said, if you want to work the old way you shouldn't have trouble declaring a variable on frame 1 like this:
var myVar:String = "Hello!";
and then accessing it on frame 15 of the same timeline like this:
trace(myVar);
If that's what you're doing and it's not working then you'll need to update your question with some code examples.
In Actionscript 3 / Flash 10, is it possible to programmatically reference a sound object that exists on the timeline? I've found lots of examples for referencing DisplayObjects via the following sytax:
var m:MovieClip = stage.getChildByName("SomeMovieClipClass");
var n:MovieClip = stage.getChildByIndex(1);
But this doesn't seem to include sound objects. Similarly, it seems straightforward to instantiate and play a sound that exists in the Library via Actionscript:
var s:SoundClip1 = new SoundClip1(); // exported in first frame via properties
s.play();
For my purposes, though, I'd like to reference sound clips (ideally in a specific layer, although that seems to be a design-time element) that designers have adjusted and arranged on the timeline, so that I can inspect their waveforms via code, at runtime. Something like this:
// Imaginary Code
sc = timeline.getSoundClipByName("SoundClip1");
sc.extract(waveform,sc.length/1000 * bitrate);
Is this possible? Thanks!
As of this date, no it is not possible to access the soundChannel generated by a timeline sound. It's a feature I would love to see implemented.
I was going to try to test the feasibility of using computeSpectrum to get the waveform of a timeline sound but I'm having problems importing mp3s right now. In absence of firsthand proof of concept, I searched around and found this thread:
http://www.kirupa.com/forum/showthread.php?t=329632
Which links to this solution
http://www.mail-archive.com/flashcoders#chattyfig.figleaf.com/msg43157.html
But of course this doesn't allow you to disambiguate between different timeline sounds. I'm pretty sure you won't be able to do that at all.
I have not ever used Sound.extract(), but if the sounds exist in the fla library this indicates to me that you can simply give them a Class name and at runtime use extract() to gather the waveform for your own purposes, yes? Then whenever the appropriate timeline sound plays, you can tap into the waveform from the Sound object. Perhaps a timeline callback or event would suffice for this?