<languageVersion: 1.0;>

kernel Desaturate
<
    namespace:      "com.27Bobs";
    vendor:         "Todd Yard";
    version:        1;
    description:    "Desaturates an image by a specified amount.";
>
{
    parameter float percent
    <
        minValue:       0.0;
        maxValue:       1.0;
        defaultValue:   1.0;
        description:    "Percent image should be desaturated.";
    >;

    const float3 grayValues = float3(0.3, 0.59, 0.11);
    
    input image4 source;
    output pixel4 result;
    
    void
    evaluatePixel()
    {
        float4 px = sampleNearest(source, outCoord());
        float distanceToDesaturatedValues = dot(px.rgb, grayValues);
        float3 fullDesaturate = float3(distanceToDesaturatedValues);
        float3 noDesaturate = px.rgb;
        px.rgb = mix(noDesaturate, fullDesaturate, percent);
        result = px;
    }
    
}