class Shader

// TODO: Document GLSL Shaders A Shader instance represents a Pixel Bender shader kernel in ActionScript. To use a shader in your application, you create a Shader instance for it. You then use that Shader instance in the appropriate way according to the effect you want to create. For example, to use the shader as a filter, you assign the Shader instance to the shader property of a ShaderFilter object. A shader defines a function that executes on all the pixels in an image, one pixel at a time. The result of each call to the function is the output color at that pixel coordinate in the image. A shader can specify one or more input images, which are images whose content can be used in determining the output of the function. A shader can also specify one or more parameters, which are input values that can be used in calculating the function output. In a single shader execution, the input and parameter values are constant. The only thing that varies is the coordinate of the pixel whose color is the function result. Shader function calls for multiple output pixel coordinates execute in parallel to improve shader execution performance.

The shader bytecode can be loaded at run time using a URLLoader instance. The following example demonstrates loading a shader bytecode file at run time and linking it to a Shader instance.

var loader:URLLoader = new URLLoader();
loader.dataFormat = URLLoaderDataFormat.BINARY;
loader.addEventListener(Event.COMPLETE, onLoadComplete);
loader.load(new URLRequest("myShader.pbj"));
var shader:Shader;

function onLoadComplete(event:Event):void {
	// Create a new shader and set the loaded data as its bytecode
	shader = new Shader();
	shader.byteCode = loader.data;

	// You can also pass the bytecode to the Shader() constructor like this:
	// shader = new Shader(loader.data);

	// do something with the shader
}

You can also embed the shader into the SWF at compile time using the [Embed] metadata tag. The [Embed] metadata tag is only available if you use the Flex SDK to compile the SWF. The [Embed] tag's source parameter points to the shader file, and its mimeType parameter is "application/octet-stream", as in this example:

[Embed(source="myShader.pbj", mimeType="application/octet-stream)] var MyShaderClass:Class;

// ...

// create a new shader and set the embedded shader as its bytecode var
shaderShader = new Shader();
shader.byteCode = new MyShaderClass();

// You can also pass the bytecode to the Shader() constructor like this:
// var shader:Shader = new Shader(new MyShaderClass());

// do something with the shader

In either case, you link the raw shader (the URLLoader.data property or an instance of the [Embed] data class) to the Shader instance. As the previous examples demonstrate, you can do this in two ways. You can pass the shader bytecode as an argument to the Shader() constructor. Alternatively, you can set it as the Shader instance's byteCode property.

Once a Shader instance is created, it can be used in one of several ways:

• A shader fill: The output of the shader is used as a fill for content drawn with the drawing API. Pass the Shader instance as an argument to the Graphics.beginShaderFill() method.
• A shader filter: The output of the shader is used as a graphic filter applied to a display object. Assign the Shader instance to the shader property of a ShaderFilter instance.
• A blend mode: The output of the shader is rendered as the blending between two overlapping display objects. Assign the Shader instance to the blendShader property of the upper of the two display objects.
• Background shader processing: The shader executes in the background, avoiding the possibility of freezing the display, and dispatches an event when processing is complete. Assign the Shader instance to the shader property of a ShaderJob instance.

Shader fills, filters, and blends are not supported under GPU rendering.

Mobile Browser Support: This feature is not supported in mobile browsers.

Adobe AIR profile support: This feature is supported on all desktop operating systems, but it is not supported on all mobile devices. It is not supported on AIR for TV devices. See AIR Profile Support for more information regarding API support across multiple profiles.