pov-ray/chain_loop.pov

#version 3.7;
#include "colors.inc"
#include "rand.inc"

global_settings {
  assumed_gamma 1.8
}

camera {
  right 1.78*x
  location <-25, -75.1, -60>
  look_at 0.1
  angle 30
}

background { color rgb <.25, .63, 1> }

light_source { <300, 300, -1000> White }

#declare half_torus = difference {
  torus {
    4,1
    sturm
    rotate x*-90  // so we can see it from the top
  }
  box { <-5, -5, -1>, <5, 0, 1> }
}
#declare chain_segment = cylinder { <0,4,0>, <0,-4,0>, 1  }

#declare flip_it = x*180;
#declare torus_trans = 8;
#declare link_trans = torus_trans*2-2*y;

#declare chain_texture = texture {
  pigment { color rgb <.49, .56, .59> }
  finish {
    ambient .1
    diffuse .4
    reflection .35
    specular 1
    metallic
  }
}

#declare chain_link = union {
  object  { half_torus                     translate  y*torus_trans/2 }
  object  { half_torus     rotate flip_it  translate -y*torus_trans/2 }
  object  { chain_segment                  translate  x*torus_trans/2 }
  object  { chain_segment                  translate -x*torus_trans/2 }
  translate y*60
}

#declare chain = union {
  #declare I = 0;
  #while(I <= 8)
    #declare R = mod(I,2);
    object { chain_link translate -y*link_trans*I rotate y*( (90*R) + ( RRand(-30, 30, 1 ) ) ) }
    #declare I = I + 1;
  #end
}


//======= RENDER
object { chain scale .45 texture { chain_texture } }
object { chain scale .45 texture { chain_texture } translate < 10, -10, -20 > rotate y*20 }
object { chain scale .45 texture { chain_texture } translate < 18, -30, -20 > rotate y*22 }
object { chain scale .45 texture { chain_texture } translate < 10, 30, 20 > rotate y*30 }