ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Filtering display objects
The code first generates two gradient circles, which are combined together to form the displacement map image. The
red circle creates the x axis displacement (xyFilter.componentX = BitmapDataChannel.RED), and the blue circle
creates the y axis displacement (xyFilter.componentY = BitmapDataChannel.BLUE). To help you understand
what the displacement map image looks like, the code adds the original circles as well as the combined circle that serves
as the map image to the bottom of the screen.
The code then loads an image and, as the mouse moves, applies the displacement filter to the portion of the image that’s
under the mouse. The gradient circles used as the displacement map image causes the displaced region to spread out
away from the pointer. Notice that the gray regions of the displacement map image don’t cause any displacement. The
gray color is 0x7F7F7F. The blue and red channels of that shade of gray exactly match the middle shade of those color
channels, so there is no displacement in a gray area of the map image. Likewise, in the center of the circle there is no
displacement. Although the color there isn’t gray, that color’s blue channel and red channel are identical to the blue
channel and red channel of medium gray, and since blue and red are the colors that cause displacement, no
displacement happens there.
Shader filter
Flash Player 10 and later, Adobe AIR 1.5 and later
The ShaderFilter class lets you use a custom filter effect defined as a Pixel Bender shader. Because the filter effect is
written as a Pixel Bender shader, the effect can be completely customized. The filtered content is passed in to the shader
as an image input, and the result of the shader operation becomes the filter result.
Note: The Shader filter is available in ActionScript starting with Flash Player 10 and Adobe AIR 1.5.
To apply a shader filter to an object, you first create a Shader instance representing the Pixel Bender shader that you
are using. For details on the procedure for creating a Shader instance and on how to specify input image and parameter
values, see “Working with Pixel Bender shaders” on page 300.
When using a shader as a filter, there are three important things to keep in mind:
The shader must be defined to accept at least one input image.
The filtered object (the display object or BitmapData object to which the filter is applied) is passed to the shader as
the first input image value. Because of this, do not manually specify a value for the first image input.
Last updated 6/6/2012
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