"Samuel B." <stb### [at] hotmailcom> wrote:
>
> Here's what I came up with this afternoon (with added border):
>

And here's the realized object. It uses a height_field for its relief, and CSG
for everything else. It fits within a box of width=.5; height=.5; depth=object
depth.

/*
 N = angular symmetry (int)
 CT = frame/circle thickness
 YC = y-cutoff for inner points
 PO = texture z offset
 RD = relief depth (height field)
 OD = object depth
 Res = height_field resolution x & y (int)
*/
#macro N_Foil_Obj(N, CT, YC, PO, RD, OD, Res)

 #declare Eps = .002; // a small value (for CSG)

 // angle map for rotation & repetition
 #local A =
  function(x, y){
   floor(atan2(x, y)/pi/2*N+.5)/N*pi*2
  }

 // distance between two rotated points
 #local Dst = vlength(<0, 1>-vrotate(<0, 1>, z*360/N));

 // circle y-position, will be also used for radius adjustment
 #local CirY = (1-CT) / (1+Dst/2) - CT;

 // circle radius
 #local CirR = (Dst/2) * CirY;

 #macro N_Foil(N, CT, YC, PO)

  // pattern function
  #local PF =
   function{
    pattern{
     pigment_pattern{
      pigment_pattern{
       planar
       translate -y
       scale CT
      }
      pigment_map{
       [0 rgb 0]
       [.025/CT granite scale .5 translate PO*z]
      }
     }
    }
   }

  // function before repetition
  #local F =
   function{
    max(
     PF(0, sqrt(x*x+pow(max(y-CirY, -YC), 2))-CirR-CT, 0),
     PF(0, -sqrt(x*x+y*y)+1-2*CT, 0)
    )
   }

  // function repeated radially with mirrored x
  #local F_ =
   function{ F(abs(x*cos(A(x, y)) - y*sin(A(x, y))), x*sin(A(x, y)) + y*cos(A(x,
y)), 0) }

  F_(2*(x-.5), 2*(-y+.5), 0)
 #end

 difference{

  // height field
  intersection{
   height_field{
    function Res, Res {
     N_Foil(N, CT, YC, PO)
    }
    smooth
    rotate x*270
    scale <1+Eps, 1+Eps, RD>
    translate -.5*(x+y)
   }
   cylinder{-z*(RD+Eps), z*OD, .5-Eps}
  }

  // x position of inner box cutout (doesn't seem to be 100% correct...)
  #local XP = abs(pow(YC, 2)-pow(CirR, 2));

  // cut out from center from previous object
  #for(I, 0, N-1)
   cylinder{<0, CirY/2, -(RD+Eps)>, <0, CirY/2, OD+Eps>, (CirR-CT)/2+Eps rotate
z*360/N*I}
   box{<-XP-Eps, 0, -(RD+Eps)>, <XP+Eps, CirY/2, OD+Eps> rotate z*360/N*I}
  #end

  // take out objects from between major circle and minor circle
  #if(true)
   intersection{
    cylinder{<0, 0, -(RD+Eps)>, <0,0, OD+Eps>, .5-CT+Eps}
    #for(I, 0, N-1)
     cylinder{<0, CirY/2, -RD>, <0, CirY/2, OD>, (CirR+CT)/2-Eps rotate
z*360/N*I inverse}
    #end
   }
  #end

  translate -z*OD
 }
#end

object{
 N_Foil_Obj(6, 0.1, 0.1, 4.0, 0.05, 0.15, 1024)
 pigment{rgb .75}
}

Post a reply to this message

Attachments:
Download 'fnfoilb-object.jpg' (102 KB)

Preview of image 'fnfoilb-object.jpg'