/* QUELQUES CUBIQUES REGLEES
S:=z-y^3-3y^2 droites : <-c,a,a*a*a+3*a*a>,<c,a,a*a*a+3*a*a>
3,<0,0,0,0,0,0,0,0,0,0,-1,0,-3,0,0,0,0,0,1,0>

S:=z*y^2-x droites : <-c*a*a+,a,-c>,<c*a*a+,a,c>>
3,<0,0,0,0,0,0,0,0,0,-1,0,1,0,0,0,0,0,0,0,0>


S:=z-xy+x^3  droites : <a,-c,-c*a-a*a*a>,<a,c,c*a-a*a*a>
3,<1,0,0,0,0,0,-1,0,0,0,0,0,0,0,0,0,0,0,1,0>

S:=z-x^2*y-x^2  droites : <a,-c,-c*a*a +a*a*a>,<a,c,c*a*a+a*a*a>
3,<0,-1,0,-1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0>

S:=z*(x^2-y^2)-2*x*y;
{3, <0,0,1.,0,0,0,-1.,0,0,0,0,-1.,0,0,0,0,0,0,0,0.>

S:=y^3+xyz-z^2
3, <0,0,0,0,0,1.,0,0,0,0,1.,0,0,0,0,0,0,-1.,0,0.>
*/ 


#include "colors.inc" 
   
#declare a=-2.5 ;
#declare b=-0.8 ;
#declare c=6 ;
#declare r=0.02 ;

   
camera  { location <-3,1,-12> look_at <2.5,-2,0>}

light_source { <-0,20,-30> color rgb<1,1,0>*0.98 } 
light_source { <-20,-20,-50> color White*0.7} 
light_source { <-20,30,-30> color White*0.9}  
 
background {rgb<0,0.6,1>*0.9}
                            
union{
   union{ 
 cylinder{  <-c,a,a*a*a+3*a*a>,<c,a,a*a*a+3*a*a>,r}
 cylinder{ <-c,b,b*b*b+3*b*b>,<c,b,b*b*b+3*b*b>,r} // S:=z-y^3-3y^2   
   
/*  cylinder{  <-c*a*a,a,-c>,<c*a*a,a,c>,r}
 cylinder{ <-c*b*b,b,-c>,<c*b*b,b,c>,r} // S:=z*y^2-x   */ 
   
/*  cylinder{ <a,-c,-c*a*a +a*a>,<a,c,c*a*a+a*a>,r}
 cylinder{ <b,-c,-c*b*b +b*b>,<b,c,c*b*b+b*b>,r} //z-x^2*y-x^2  */
      
/*cylinder{<a, -c/a+a*a, -c>,<a, c/a+a*a,c>,r}
 cylinder{<b, -c/b+b*b, -c>,<b, c/b+b*b,c>,r} //z=x*y-x^3 */

         pigment{Cyan}
        }
       
 //droites : 

poly{3,<0,0,0,0,0,0,0,0,0,0,-1,0,-3,0,0,0,0,0,1,0>} // S:=z-y^3-3y^2
      
// poly{3 <0,0,0,0,0,0,0,0,0,-1,0,1,0,0,0,0,0,0,0,0>} // S:=z*y^2-x
//poly{3,<0,-1,0,-1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0> }// S:=z-x^2*y-x^2
//poly{ 3, <1,0,0,0,0,0,-1,0,0,0,0,0,0,0,0,0,0,0,1,0> //z=x*y-x^3 }
//poly{3,  <0,0,1.,0,0,0,-1.,0,0,0,0,-1.,0,0,0,0,0,0,0,0.>  //z*(x^2-y^2)-x*y    
    clipped_by {  sphere{ <0,-1,2>, 6  } } 
  
    bounded_by { clipped_by } 

    pigment { rgb <1,.75,.1>*0.6 } 
    finish { ambient 0.6 diffuse 0.7 specular .5 roughness 0.05} 
    rotate <20,-50,80>
    scale <2,1,1>  
   
  }