/*
 POV-Ray 3.1e demonstration of
 CRC Standard surface 9.4.4 4 given on page 298
 of CRC Standard Curves & Surfaces; CRC press 1993
 <davidwilkinson@cwcom.net>
 
It uses P_surfa.inc by David Sharp <dsharp@interport.net>
*/


#include "colors.inc"
#include "textures.inc"
#include "metals.inc"

global_settings { max_trace_level 7 }

// ** required for p_surfa.inc

#declare uusteps = 40;	// **
#declare vvsteps = 40;	//  **
#declare vvmin   = -10;	// **
#declare vvmax   =  10;	// **
#declare uumin   = -20;	// **
#declare uumax   =  20;	// **


#declare a1=0.1;
#declare b1=0.01;

#macro Zvalue (u1,v1)
  a1*u1*u1 + b1*v1*v1*v1
#end

#macro xyz(u1,v1)	
    < u1,
     v1,
    Zvalue (u1,v1)>
#end

#declare use_smooth_triangles=1;// **

#include "p_surfa.inc"

   
object{
	p_surface
	texture{T_Brass_5D}
        rotate -10*y
}

camera
{ 
  location  < 15, .5,-30>
  look_at   < 1, .5, .5>
} 

light_source { <40, 20, -20> color rgb 1 }

sky_sphere{
    pigment {
        bozo
        color_map {
            [ 0.00 rgb < 0.000, 0.000, 0.000 > ]
            [ 0.35 rgb < 0.1, 0.1, 0.25 > ]
            [ 0.65 rgb < 0.400, 0.350, 0.420 > ]
            [ 1.00 rgb < 0.15, 0.150, 0.150 > ]
        }
        turbulence < 0.400, 0.600, 0.200 >
    }
}