Well, I finally found some time to dive into the Pixel Bender pool and start playing around with that new technology that came from Adobe-land. And this is what I came up with for my very first attempt: nothing too fancy, just the Pixel Bender version of the well known ”Pixelate” PhotoShop filter. Give it a whirl by adjusting the pixel size with the slider. Flash Player 10 required of course.

Here’s a working example. Just play around with the Pixel size slider.

You can check the ActionScript source code and here comes the Pixel Bender kernel source:

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<languageVersion : 1.0;>

kernel Pixelate
<
   namespace : "net.riastar.shader";
   vendor : "RIAstar";
   version : 1;
   description : "pixelates an image";
>
{
   input image4 src;
   output pixel4 dst;

   parameter float size
   <
      minValue: 1.0;
      maxValue: 20.0;
      defaultValue: 4.0;
   >;

   void evaluatePixel() {
      float2 pos = outCoord();
      float center = (size + 1.0) / 2.0;

      dst = sampleNearest(src, float2(
         pos.x - mod(pos.x, size) + center,
         pos.y - mod(pos.y, size) + center
      ));

      //make sure not to sample outside the borders
      if (dst.a &lt;= 0.0)
         dst = sampleNearest(src, float2(
            pos.x - mod(pos.x, size),
            pos.y - mod(pos.y, size)
         ));
   }
}

I had quite a hard time getting it to work in ActionScript, apparently because I installed the Flex 3.3 SDK just a week ago. Just putting a declaration of a flash.display.Shader class in my code, was sufficient to stop all code from executing, although the VM did not crash. I also got no error message whatsoever.

So after a whole hour of trying everything I could think of, I told the compiler to use the old 3.2 SDK and tadaa: working like a charm. Is it a bug in 3.3 (which was meant to be a bugfix release in the first place) or did I do something wrong?