kernel Ripple
<   nameSpace: "popforge::ImageProcessing";
    vendor: "joa ebert";
    version: 1;
    description: "applies a sine wave distortion";
>
{
    parameter float2 frequency<
        minValue: float2(0.0,0.0);
        maxValue: float2(0.5,0.5);
        defaultValue: float2(0.06125,0.06125);
        description: "frequency of the sine wave";
    >;
    
    parameter float2 amplitude<
        minValue: float2(0.0,0.0);
        maxValue: float2(64.0,64.0);
        defaultValue: float2(4.0,4.0);
        description: "amplitude of the sine wave";
    >;
    
    void evaluatePixel(in image4 source, out pixel4 result)
    {
        float2 xy = outCoord();
        
        xy = xy + amplitude * sin( xy.yx * frequency.xy );
        
        result = sampleLinear(source,xy);
    }
}