ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with Pixel Bender shaders
You use a ShaderJob object to execute a shader in stand-alone mode. First you create the ShaderJob object and link it
to the Shader object representing the shader to execute:
var job:ShaderJob = new ShaderJob(myShader);
Next, you set any input or parameter values that the shader expects. If you are executing the shader in the background,
you also register a listener for the ShaderJob object’s complete event. Your listener is called when the shader finishes
its work:
function completeHandler(event:ShaderEvent):void
{
// do something with the shader result
}
job.addEventListener(ShaderEvent.COMPLETE, completeHandler);
Next, you create an object into which the shader operation result is written when the operation finishes. You assign
that object to the ShaderJob object’s target property:
var jobResult:BitmapData = new BitmapData(100, 75);
job.target = jobResult;
Assign a BitmapData instance to the target property if you are using the ShaderJob to perform image processing. If
you are processing binary or number data, assign a ByteArray object or Vector. instance to the target
property. In that case, you must set the ShaderJob object’s width and height properties to specify the amount of data
to output to the target object.
Note: You can set the ShaderJob object’s shader, target,width, and height properties in one step by passing arguments
to the ShaderJob() constructor, like this:var job:ShaderJob = new ShaderJob(myShader, myTarget, myWidth,
myHeight);
When you are ready to execute the shader, you call the ShaderJob object’s start() method:
job.start();
By default calling start() causes the ShaderJob to execute asynchronously. In that case program execution continues
immediately with the next line of code rather than waiting for the shader to finish. When the shader operation finishes,
the ShaderJob object calls its complete event listeners, notifying them that it is done. At that point (that is, in the body
of your complete event listener) the target object contains the shader operation result.
Note: Instead of using the target property object, you can retrieve the shader result directly from the event object that’s
passed to your listener method. The event object is a ShaderEvent instance. The ShaderEvent object has three properties
that can be used to access the result, depending on the data type of the object you set as the target property:
ShaderEvent.bitmapData, ShaderEvent.byteArray, and ShaderEvent.vector.
Alternatively, you can pass a true argument to the start() method. In that case the shader operation executes
synchronously. All code (including interaction with the user interface and any other events) pauses while the shader
executes. When the shader finishes, the target object contains the shader result and the program continues with the
next line of code.
job.start(true);
Last updated 6/6/2012
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