/*
 POV-Ray 3.1e demonstration of
 CRC Standard surface 8.4.1  1. given on page 282
 of CRC Standard Curves & Surfaces CRC press 1993

It uses P_surfa.inc by David Sharp <dsharp@interport.net>

*/

#include "colors.inc"
#include "textures.inc"
#include "metals.inc"
#include "Axes1.inc"

global_settings { max_trace_level 7 }


#declare uusteps = 40;	
#declare vvsteps = 40;	
#declare vvmin   = -1;
#declare vvmax   =  1;
#declare uumin   = -1;
#declare uumax   =  1;

#declare a1=1;
#declare b1=1;
#declare c1=0.5;

#macro Zvalue (u1,v1)
 c1*(v1*v1*v1/(a1*a1*a1) + u1*u1*u1/(b1*b1*b1))
#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 90*x
}

//Axes(20)

camera
{ 
  location  < 0.25, 0, 3>
  look_at   < 0.25, 0, 0>
} 

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 >
    }
}

sphere { 0,100 translate -150*z pigment{White}}