/*****************************************************************************
 *
 * Author: Andy Zupko 
 * http://blog.zupko.info
 * 
 * Write me if you use this for anything cool!
 *
 *****************************************************************************/


kernel Bullseye
{
    parameter int width
    <
        defaultValue:   400;
        minValue:       1;
        maxValue:       800;
       
    >;
    
   
    parameter int height
    <
        defaultValue:   400;
        minValue:       1;
        maxValue:       800;
       
    >;
    
    parameter float spread
    <
    defaultValue:40.0;
    minValue:1.0;
    maxValue:200.0;
    >;
    
    
    parameter float2 center
    <
    minValue: float2(0.0, 0.0);
    maxValue:float2(2000.0, 2000.0);
    defaultValue:float2(100.0,100.0);
    >;
    
    
    
    void
    evaluatePixel(out pixel4 result)
    {
        float2 coord = outCoord();
        float2 pos = coord-center;
        float dist = length(pos);
        
        float cosn = cos(dist/spread);
           
        float a = 1.0;
        
        result = pixel4(cosn,cosn,cosn,1.0);
    }
    
    region generated()
    {
        return region(float4(0,0,width,height));
    }
}