If you build in Flash, you know that each new release of Flash will have new features in Actionscript3. For example, there is a bug in Flash 9 (CS3) with the Loader.unload() method that can cause it to hang on to the loaded item in memory (details here). This was fixed (sort of) in Flash 10 with the Loader.unloadAndStop() method. There are also other features, such as byteArrays that weren’t available in Flash 9, but were added in Flash 10.
At my job, we have created a class package for commonly used functionality, such as asset loading. But what if we want to use a method like Loader.unloadAndStop() in one of these classes? If the project is published in Flash 9, the compiler will throw an error. We could simply use the Loader.unload() method, but we really want to use newer method if the project is published in Flash 10. As always, the Flash community comes to my rescue with this:
This handy little snippet of code will work in any version of AS3. It looks for the newer function and runs it if it exists. If it doesn’t exist, it reverts back to the older code. This is a lifesaver. It allows me to run the “best” version of Actionscript, based on the publish settings of the project.
The original forum thread where I found this solution is here.
I just finished a project that allowed a user to dynamically draw lines on a chalkboard. Obviously, I used the Flash drawing API to draw the lines, but I wanted to give the lines a chalk texture. I figured it would be simple – just create a background texture that looked like chalk and use the dynamically drawn lines as a mask…
Wrong! Flash can’t use dynamically drawn lines as a mask. It can use dynamically drawn shapes (like circles and rectangles) without a problem as long as they have a fill color. Unfortunately, Flash considers all lines to be infinitely thin vectors, so they don’t work as a mask. Even if you set the lineStyle property to be really wide, Flash simply can’t use the lines to create a mask.
I figured out a relatively easy way to do this. Check out the example below:
How is this done? Essentially, you can get around Flash's issues by creating a transparent bitmap copy of your dynamically drawn lines and then using the bitmap as your mask. Do this on every frame and you have a dynamic mask using the drawing API! Of course, with Flash, there is always a catch. The catches are:
You must set the BitmapData properties correctly to create a transparent bitmap (download the example and check it out)
You must set cacheAsBitmap to true for both the new mask and the masked object or this doesn't work.
As always, I've included a source file download. I commented this one VERY thoroughly, so you should be able to implement it pretty easily. You can toggle the "enableMasking" property in the code to see the line drawing without the masking. Combine this with my earlier post on drawing smooth lines and you can make something really cool. Good Luck!
Five3D is a compact Actionscript library that allows you to create 3D views quickly and easily. Much like Papervision3D, Away3D or Sandy, it allows you to create basic 3D graphics with Actionscript. Why would you use Five3D instead of one of these other libraries? Here’s a quick rundown of the advantages and shortcomings of Five3DÂ that I have found:
Five3D has a stripped-down feature set. If you need to do something simple like move a large number of planes in 3D space, Five3D will be easier to set up than the other 3D packages. The drawback is that it doesn’t do many of the things that the other engines do, like providing built-in primitives or Collada imports.
Five3D handles vector objects without first turning them into bitmaps. You can actually use Flash’s native drawing API to create vector shapes and move them in 3D while still retaining the vectors. This creates smoother renders than the other 3D engines, especially when scaling and rotating objects. The other 3D engines create bitmaps of textures and then map them onto the surfaces of objects.
Five3D handles 3D text really well. You can convert fonts into vectors and then use them as 3D objects. This makes 3D text effects really simple.
The default handling of bitmap textures is cleaner than Papervision. With Five3D, bitmap textures on planes map much more smoothly than with Papervision’s defaults. You can map textures just as well in Papervision, but it’s a little bit of a hassle to set up.
The Five3D library is written to extend the native flash classes in a way that is really intuitive. For example, a MovieClip3D is just like a MovieClip, but it has additional features like a z-coordinate. Half the time, you can guess what properties each object will have without even looking them up in the docs.
Five3D doesn’t use a camera object. Depending on your needs, this could be an advantage or a disadvantage. You can handle this by simply creating a Sprite3D container to hold all of your objects. Then, move the container to simulate camera movement. I often do this in Papervision projects anyway because of various issues I have had with the camera.
I have built a simple “Hello World” test of Five3D, which you can see below. It’s not very exciting, but it isn’t supposed to be. When I started playing with Five3D, I had a hard time finding a simple, stripped-down example that could get me started, so that is what I’ve built here. You can download the source files here. I have also added links to some more advanced tutorials and samples at the bottom of this post.
I did run into some weird Five3D quirks when I built this. First, when I created a MovieClip3D object and added it to the scene, it wasn't appearing on stage. I traced all of the properties and everything indicated that it was on the stage, but it was not displaying. I Googled around a bit and found this website with the answer: you have to call the activate() function for MovieClip3D objects to get them to render on the stage. I don't understand why you need to do this, but it fixed my problem.
The other quirk that you need to know about is that you have to turn on z-sorting. By default, it z-sorts according to your addChild() calls, just like regular MovieClips. If you don't need z-sorting, just add the 3D items in the correct sequence. I'm guessing that this helps to optimize the code. If you need your objects to spin in 3D space, you can turn on z-sorting with the childrenSorted property (check out the example source code for usage).
Thanks to Mathieu Badimon for this amazing Actionscript package.
As I have made the transition to AS3 class-based programming, I have built a package of useful classes that handle functionality I need all the time. For example, I have a class that handles the basic rollover functionality for a button. Rather than write this code over and over, I made a class that takes care of it. That’s the main benefit of working in classes – things become more modular and you (theoretically) spend less time building repetitive code. I am always looking for good code to add to my core package of classes and the following two classes definitely fit the bill. I use them all the time and I thought I’d help more people locate them:
getURL:
One of the biggest hassles in AS3 is writing 10 lines of code to accomplish the same thing that you can do with one line in AS2. The getURL() function was killed in AS3. Now you need to set up a URLRequest… it’s a hassle. Well, Actionscript guru Senocular has created a getURL() class that mimics the behavior of the AS2 function. simply add the class to your import statements and then use it just like you did in AS2. Grab it here.
Pixel Perfect Collision:
One of the more annoying problems with Flash is that collision-detection has never lived up to its promise. In AS2, the hitTest() function only allowed you to check if the bounding boxes of 2 objects were touching. This worked great if all of your graphics were rectangular, but it often registered a collision between objects that, visually, looked like they were still pretty far apart. Grant Skinner was the first person to solve this problem with his AS2 collision-detection code. His original code was then ported to as3 by Boulevart. I had been using that code for projects, but it had a few shortcomings – it didn’t work for rotated or scaled objects and both objects had to share the same parent. I was just recently contemplating an update to the AS3 Collision class to fix some of these issues when I found an updated version by Troy Gilbert. It not only handles rotated and scaled objects, but he has optimized the code and removed the constructor (which was really unnecessary anyway). You will definitely want to get his PixelPerfectCollision class.
That’s all for now. If you’ve found any other classes that you use all the time, leave a comment and let me know.
