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#declare F1=function(u,v){cos(u)+v*cos(u/2)*cos(u)}
#declare F2=function(u,v){sin(u)+v*cos(u/2)*sin(u)}
#declare F3=function(u,v){v*sin(u/2)}              
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#include "meshmaker.inc"
//-------------------------------------------------------------------------------------------------
object{ // Parametric(Fx,Fy, Fz, <UVmin>, <UVmax>, Iter_U, Iter_V, FileName)
   Parametric( // Builds a parametric surface out of three given functions. 
               // The uv_coordinates for texturing the surface come from the square <0,0> - <1,1>. 
      F1, F2, F3, //three functions
      <0, -0.5>, <2*pi, 0.5>,// range within to calculate surface: <u min, v min>,<u max, v max>. 
      50, 100, // resolution of the mesh in the u range and v range.
       "" // FileName: ""= non, "NAME.obj'= Wavefront objectfile, "NAME.pcm" compressed mesh file 
          // "NAME.arr" = include file with arrays to build a mesh2 from, 
          //  others: includefile with a mesh2 object 
   ) //---------------------------------------------------------------------------------------------
 //  no_shadow
   interior_texture {  //  outside texture
     uv_mapping
     pigment{ checker color rgb <0.0,0.3,0.5> rgb <1,1,1> scale <0.02,0.15,1>}
     finish { specular 0.25}
   } // 
   texture{            // inside texture
     uv_mapping
     pigment{ checker color rgb <0.0,0,0.0> rgb <1,0.9,0.9> scale <0.02,0.15,1>}
     finish { phong 0.5 }
   } // 
   
   rotate<0,0,0>
   scale<1,1,1>*1
   translate< 0, 0, 0 >
} // end of object 
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