//Surfaces with critical points
//by Adam Coffman                
//June 2006

camera {
    location  <-0.875,0.675,1.2>
    look_at   <0,0, 0>
      }

 #include "colors.inc"
 background{White}
// #declare T=1/2*(1-cos(2*pi*(clock+0.01)));
 #declare T1=0;
 #declare T2=-0.3;
  poly { 4 <
    2,0,0,0,0,0,0,0,0,2+2*T2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,-1,-2,0,-2*T2,-2*T1,0>
    sturm 
 pigment {
   brick   rgb <0,0,0,0,0>  rgb <0,0,1,0,.6>
   brick_size <50,0.0225,50> mortar 0.00475     
   translate <2,0.001125,2> 

 }
    bounded_by { cylinder{<0,3,0> <0,-3,0> 0.52 }  }
    clipped_by { bounded_by }
                  
   }
  
  light_source{<0.5,20,0> White} 
 light_source{<-40,0,0.5> White shadowless}
  light_source{<40,0,0.5> White shadowless}
  light_source{<0,0.5,40> White shadowless}