Blur.pbk

<languageVersion : 1.0;>

kernel Blur
<   namespace : "Blur";
    vendor : "Paperless Post";
    version : 1;
>
{
    input image4 src;
    output pixel4 dst;

    /*parameter float strength
    <
        minValue:float(0.0);
        maxValue:float(1.0);
        defaultValue:float(0.5);
    >;*/

    parameter float threshold
    <
        minValue:float(0.0);
        maxValue:float(1.0);
        defaultValue:float(0.5);
    >;
    
    void
    evaluatePixel()
    {
        float2 pos = outCoord();
        dst = sampleNearest(src, pos);
        float strength = length(dst.rgb) / length(float3(1.0,1.0,1.0));
        if(strength > threshold){
            dst += sampleNearest(src, float2(pos.x-1.0,pos.y-1.0)); 
            dst += sampleNearest(src, float2(pos.x,pos.y-1.0));
            dst += sampleNearest(src, float2(pos.x+1.0,pos.y-1.0));
            dst += sampleNearest(src, float2(pos.x-1.0,pos.y));
            dst += sampleNearest(src, float2(pos.x+1.0,pos.y));
            dst += sampleNearest(src, float2(pos.x-1.0,pos.y+1.0));
            dst += sampleNearest(src, float2(pos.x,pos.y+1.0));
            dst += sampleNearest(src, float2(pos.x+1.0,pos.y+1.0));
            dst += sampleNearest(src, float2(pos.x-2.0,pos.y-2.0));
            dst += sampleNearest(src, float2(pos.x-1.0,pos.y-2.0));
            dst += sampleNearest(src, float2(pos.x,pos.y-2.0));
            dst += sampleNearest(src, float2(pos.x+1.0,pos.y-2.0));
            dst += sampleNearest(src, float2(pos.x+2.0,pos.y-2.0));
            dst += sampleNearest(src, float2(pos.x-2.0,pos.y-1.0));
            dst += sampleNearest(src, float2(pos.x+2.0,pos.y-1.0));
            dst += sampleNearest(src, float2(pos.x-2.0,pos.y));
            dst += sampleNearest(src, float2(pos.x+2.0,pos.y));
            dst += sampleNearest(src, float2(pos.x-2.0,pos.y+1.0));
            dst += sampleNearest(src, float2(pos.x+2.0,pos.y+1.0));
            dst += sampleNearest(src, float2(pos.x-2.0,pos.y+2.0));
            dst += sampleNearest(src, float2(pos.x-1.0,pos.y+2.0));
            dst += sampleNearest(src, float2(pos.x,pos.y+2.0));
            dst += sampleNearest(src, float2(pos.x+1.0,pos.y+2.0));
            dst += sampleNearest(src, float2(pos.x+2.0,pos.y+2.0));
            
            dst/= 24.0;
            
            dst = mix(sampleNearest(src,pos),dst,strength);
        }
    }
}