<languageVersion : 1.0;>

kernel Painting
<   namespace : "ar.shader.painting";
    vendor : "Alan Ross";
    version : 1;
    description : "Painting";
>
{
    parameter float n0
    <
        minValue: 0.0;
        maxValue: 1.0; 
        defaultValue: 0.0;
    >;
    parameter float n1
    <
        minValue: 0.0;
        maxValue: 1.5; 
        defaultValue: 0.6;
    >;
    parameter float n2
    <
        minValue: -0.5; 
        maxValue: 0.5; 
        defaultValue: 0.11;
    >;

    input image4 src;
    output pixel4 dst;
     
    void evaluatePixel()
    {
        float2 p = outCoord();
        float2 offset;
        float dist;
        float4 c, temp, p0, p1, p2, p3, p4, p5, p6, p7, p8;
        
        c = float4( n0, n0, n0, 1.0 );
        
        //-- no loops.
        
        dist = n1 * 1.0;
        offset.x = 0.0; offset.y = 0.0;
        p0 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y = -dist;
        p1 = sampleNearest( src, p + offset ); offset.x =  0.0;  offset.y = -dist;
        p2 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y = -dist;
        p3 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y =  0.0;
        p4 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y =  dist;
        p5 = sampleNearest( src, p + offset ); offset.x =  0.0;  offset.y =  dist;
        p6 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y =  dist;
        p7 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y =  0.0;
        p8 = sampleNearest( src, p + offset ); 
        
        if( any( lessThan( c, p0 ) ) ){ c = p0; }
        if( any( lessThan( c, p1 ) ) ){ c = p1; }
        if( any( lessThan( c, p2 ) ) ){ c = p2; }
        if( any( lessThan( c, p3 ) ) ){ c = p3; }
        if( any( lessThan( c, p4 ) ) ){ c = p4; }
        if( any( lessThan( c, p5 ) ) ){ c = p5; }
        if( any( lessThan( c, p6 ) ) ){ c = p6; }
        if( any( lessThan( c, p7 ) ) ){ c = p7; }
        if( any( lessThan( c, p8 ) ) ){ c = p8; }
        
        temp = ( p1 + p2 + p3 + p4 + p5 + p6 + p7 + p8 ) / 7.0;
        
        dist = n1 * 2.0;
        offset.x = 0.0; offset.y = 0.0;
        p0 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y = -dist;
        p1 = sampleNearest( src, p + offset ); offset.x =  0.0;  offset.y = -dist;
        p2 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y = -dist;
        p3 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y =  0.0;
        p4 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y =  dist;
        p5 = sampleNearest( src, p + offset ); offset.x =  0.0;  offset.y =  dist;
        p6 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y =  dist;
        p7 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y =  0.0;
        p8 = sampleNearest( src, p + offset );

        if( all( lessThan( c, temp ) ) ){ c.rgb += n2; }
        else { c.rgb -= n2; }
        
        if( any( lessThan( c, p0 ) ) ){ c = p0; }
        if( any( lessThan( c, p1 ) ) ){ c = p1; }
        if( any( lessThan( c, p2 ) ) ){ c = p2; }
        if( any( lessThan( c, p3 ) ) ){ c = p3; }
        if( any( lessThan( c, p4 ) ) ){ c = p4; }
        if( any( lessThan( c, p5 ) ) ){ c = p5; }
        if( any( lessThan( c, p6 ) ) ){ c = p6; }
        if( any( lessThan( c, p7 ) ) ){ c = p7; }
        if( any( lessThan( c, p8 ) ) ){ c = p8; }
        
        dist = n1 * 3.0;
        offset.x = 0.0; offset.y = 0.0;
        p0 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y = -dist;
        p1 = sampleNearest( src, p + offset ); offset.x =  0.0;  offset.y = -dist;
        p2 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y = -dist;
        p3 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y =  0.0;
        p4 = sampleNearest( src, p + offset ); offset.x =  dist; offset.y =  dist;
        p5 = sampleNearest( src, p + offset ); offset.x =  0.0;  offset.y =  dist;
        p6 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y =  dist;
        p7 = sampleNearest( src, p + offset ); offset.x = -dist; offset.y =  0.0;
        p8 = sampleNearest( src, p + offset );

        if( any( lessThan( c, p0 ) ) ){ c = p0; }
        if( any( lessThan( c, p1 ) ) ){ c = p1; }
        if( any( lessThan( c, p2 ) ) ){ c = p2; }
        if( any( lessThan( c, p3 ) ) ){ c = p3; }
        if( any( lessThan( c, p4 ) ) ){ c = p4; }
        if( any( lessThan( c, p5 ) ) ){ c = p5; }
        if( any( lessThan( c, p6 ) ) ){ c = p6; }
        if( any( lessThan( c, p7 ) ) ){ c = p7; }
        if( any( lessThan( c, p8 ) ) ){ c = p8; }
        
        dst = c;
    }
}