<languageVersion : 1.0;>
kernel Flashlight
<
    namespace : "Light";
    vendor : "Ronen Tsamir";
    version : 1;
    description : "Flashlight effect";
>
{
    // Set The input parameters
    parameter float radius
    <
    minValue: 0.0;
    maxValue: 600.0;
    defaultValue: 30.0;
    >;
   
    parameter pixel4 color
    <
    minValue: float4(0.0,0.0,0.0,0.0);
    maxValue: float4(2.0,2.0,2.0,2.0);
    defaultValue: float4(0.58,0.94,0.84,0.02);
    >;
    parameter pixel2 center
    <
    minValue: pixel2(0,0);
    maxValue: pixel2(500,500);
    defaultValue: pixel2(200,200);
    >;
   
    input image4 src;
    output pixel4 result;
    // this functuin call for each pixel.
    void evaluatePixel()
    {
        // Get the current pixel location
        float2 coord_for_this_pixel = outCoord();
        // Get the distance from the center
        pixel2 C;
        C.x= coord_for_this_pixel.x - center.x;
        C.y= coord_for_this_pixel.y - center.y;
        float R = sqrt(C.x * C.x + C.y * C.y);
        //  manipulation the outpot color of the pixel.
        result = sampleNearest(src, coord_for_this_pixel) * (1.0 + color -  color *  sqrt(R / radius));

    }
}