// adding a photon{} block to global_settings activates photon mapping.
// photons also need to be adjusted for light sources and objects.
global_settings {
  photons {
    spacing 0.01                 // specify the density of photons
    //count 100000               // alternatively use a total number of photons

    //gather min, max            // amount of photons gathered during render [20, 100]
    //media max_steps [,factor]  // media photons
    //jitter 1.0                 // jitter phor photon rays
    //max_trace_level 5          // optional separate max_trace_level
    //adc_bailout 1/255          // see global adc_bailout
    //save_file "filename"       // save photons to file
    //load_file "filename"       // load photons from file
    //autostop 0                 // photon autostop option
    //radius 10                  // manually specified search radius
    // (---Adaptive Search Radius---)
    //steps 1
    //expand_thresholds 0.2, 40 
  }
}


 global_settings { assumed_gamma 0.2 }




///////////////////////////////
// perspective (default) camera
camera
{
  location  <-3.0 , 2.0 ,-5.0>
  look_at   <0.0 , 0.0 , 0.0>
}
   
// An area light (creates soft shadows)
// WARNING: This special light can significantly slow down rendering times!
/*light_source
{
  0*x                 // light's position (translated below)
  color rgb 1.0       // light's color
  area_light
  <8, 0, 0> <0, 0, 8> // lights spread out across this distance (x * z)
  4, 4                // total number of lights in grid (4x*4z = 16 lights)
  adaptive 0          // 0,1,2,3...
  jitter              // adds random softening of light
  circular            // make the shape of the light circular
  orient              // orient light
  translate <40, 80, -40>   // <x y z> position of light
} */


//////////////////////////////






#declare OpticalPrism = 
        
prism {
  linear_sweep // or conic_sweep for tapering to a point
  linear_spline 
  -0.5,        // height 1
   0.5,        // height 2
  4,          // number of points
  // the <u,v> points
  < 0, -sqrt(3)/4>, < -.5, sqrt(3)/4 >, < .5, sqrt(3)/4> , < 0, -sqrt(3)/4>
  // [open]
  // [sturm]
  
  pigment { rgbf 1 }
  interior {
        ior 1.5
        dispersion 1.05
  }   
 // photon block for an object
  photons{
    target 1.0          // spacing multiplier for photons hitting the object
    refraction on
    reflection on
    //ignore_photons
    //pass_through
  }


}
  
  
// atmospheric media can be generated by adding a media statement
// to the scene not attached to any specific object

media {    // atmospheric media sample
  intervals 10
  scattering { 1, rgb 0.3}
  samples 1, 10
  confidence 0.9999
  variance 1/1000
  ratio 0.9
}
  
  
 
// Create an infinite sphere around scene and allow any pigment on it
sky_sphere
{
  pigment
  {
    spherical
    color_map { [0.0 color rgb <0.7,0.7,1.0>] [1.0 color blue 0.5] }
  }
}
 
 

object{OpticalPrism rotate x*-90 }                                                 


plane
{
  y, // <X Y Z> unit surface normal, vector points "away from surface"
  -1.0 // distance from the origin in the direction of the surface normal
  hollow on // has an inside pigment?
  pigment { 
   
      color rgb <1, 1, 1>
    
  }

}    

plane
{
  y, // <X Y Z> unit surface normal, vector points "away from surface"
  -1.0 // distance from the origin in the direction of the surface normal
  hollow on // has an inside pigment?
  pigment { 

      color rgb <1, 1, 1>
    
  }

  rotate z*90
  translate x*6
}



// create a point "spotlight" (cylindrical directed) light source
light_source
{
  0*x                     // light's position (translated below)
  color rgb 5*<1,1,1>     // light's color
  spotlight               // this kind of light source
  cylinder                // this variation 
  parallel
  translate <-8, 0,0>     // <x y z> position of light
  point_at <5, 0, 0>      // direction of spotlight
  radius .2               // hotspot (inner, in degrees)
  tightness 99            // tightness of falloff (1...100) lower is softer, higher is tighter
  falloff 8               // intensity falloff radius (outer, in degrees) 
  // photon block for a light source
  photons {
    refraction on 
    
    //area_light
  }

  media_interaction on
}