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This image was created using POV-Ray for Windows, version 3.6. The image was rendered to an 1800 x 1800 square, using 0.3 anti-aliasing.

#include "colors.inc"

background { color White }

global_settings { assumed_gamma 1.0}

camera
  {
  location <0, 0, -25>
  right <1,0,0> up <0,1,0>
  look_at  <0, 0, 0>
  angle 5
  }


light_source
  {
  <0, 20, -50>
  color White
  area_light <5, 0, 0>, <0, 5, 0>, 10, 10  /* very slow, decrease 10 to 2 for experiments */
  adaptive 3
  }


#declare r_tube = 0.08;  // thickness (radius) of tube
#declare num_steps = 48;  // number of spline points
#declare step_size = 1/num_steps;
              

sphere_sweep
  {
  cubic_spline 72,
  <-0.743926,-0.323044,-0.0374538>, r_tube
  <-0.712114,-0.43569,0.0298152>, r_tube
  <-0.657593,-0.539064,0.0973434>, r_tube
  <-0.580001,-0.628497,0.162174>, r_tube
  <-0.480129,-0.698632,0.220002>, r_tube
  <-0.361141,-0.743997,0.265224>, r_tube
  <-0.229443,-0.759909,0.291525>, r_tube
  <-0.0949831,-0.743633,0.292938>, r_tube
  <0.0290111,-0.695571,0.265328>, r_tube
  <0.127664,-0.620327,0.208148>, r_tube
  <0.187943,-0.526887,0.125706>, r_tube
  <0.202792,-0.42621,0.0272863>, r_tube
  <0.17111,-0.32591,-0.0709779>, r_tube
  <0.0972916,-0.227153,-0.144044>, r_tube
  <-0.00303469,-0.130199,-0.167725>, r_tube
  <-0.105695,-0.0395859,-0.134719>, r_tube
  <-0.192521,0.0426878,-0.0584242>, r_tube
  <-0.258908,0.125519,0.0364681>, r_tube
  <-0.306283,0.222655,0.126588>, r_tube
  <-0.332389,0.339841,0.196062>, r_tube
  <-0.332078,0.471357,0.236057>, r_tube
  <-0.302211,0.604663,0.243255>, r_tube
  <-0.243592,0.725428,0.218848>, r_tube
  <-0.160735,0.820618,0.167595>, r_tube
  <-0.0609402,0.880171,0.0968376>, r_tube
  <0.0467134,0.897821,0.0156533>, r_tube
  <0.152292,0.871534,-0.0658683>, r_tube
  <0.245965,0.803746,-0.137469>, r_tube
  <0.31894,0.701332,-0.189551>, r_tube
  <0.364616,0.575224,-0.214088>, r_tube
  <0.379764,0.439493,-0.205788>, r_tube
  <0.365485,0.30926,-0.16329>, r_tube
  <0.327266,0.196744,-0.0903403>, r_tube
  <0.27163,0.10534,0.00298281>, r_tube
  <0.200056,0.0254783,0.0984198>, r_tube
  <0.110533,-0.0587019,0.170319>, r_tube
  <0.00963576,-0.154385,0.19444>, r_tube
  <-0.0823127,-0.256527,0.160722>, r_tube
  <-0.141554,-0.357878,0.0795114>, r_tube
  <-0.154315,-0.455221,-0.0247574>, r_tube
  <-0.118171,-0.545017,-0.12782>, r_tube
  <-0.0372333,-0.619017,-0.213077>, r_tube
  <0.0777866,-0.667792,-0.27036>, r_tube
  <0.211105,-0.685624,-0.295104>, r_tube
  <0.346655,-0.671631,-0.288075>, r_tube
  <0.471388,-0.628678,-0.253863>, r_tube
  <0.576552,-0.561812,-0.199031>, r_tube
  <0.657697,-0.476737,-0.130543>, r_tube
  <0.713605,-0.378719,-0.0546503>, r_tube
  <0.744743,-0.271947,0.0235513>, r_tube
  <0.751811,-0.159612,0.0998334>, r_tube
  <0.73477,-0.0444363,0.170189>, r_tube
  <0.692907,0.0705058,0.230027>, r_tube
  <0.625781,0.18087,0.273654>, r_tube
  <0.534857,0.280625,0.294572>, r_tube
  <0.425349,0.362575,0.286687>, r_tube
  <0.306944,0.420442,0.246406>, r_tube
  <0.19151,0.452695,0.17491>, r_tube
  <0.0866572,0.465806,0.0794595>, r_tube
  <-0.0108419,0.470164,-0.0267027>, r_tube
  <-0.112128,0.467972,-0.127405>, r_tube
  <-0.224385,0.450555,-0.208965>, r_tube
  <-0.344022,0.409211,-0.263201>, r_tube
  <-0.460559,0.342175,-0.287556>, r_tube
  <-0.563557,0.253287,-0.284262>, r_tube
  <-0.646168,0.148681,-0.25848>, r_tube
  <-0.705409,0.0343619,-0.216228>, r_tube
  <-0.740931,-0.084795,-0.162849>, r_tube
  <-0.753536,-0.204989,-0.102349>, r_tube
  <-0.743926,-0.323044,-0.0374538>, r_tube
  <-0.712114,-0.43569,0.0298152>, r_tube
  <-0.657593,-0.539064,0.0973434>, r_tube
  pigment { color rgb <0,0.25,1> }
  finish          
    {
    ambient 0.15
    diffuse 0.85
    brilliance 2
    phong 0.25
    phong_size 7
    }
  }

plane
  {
  <0,0,-1>, -0.38
  pigment { color White }
  finish
    {
    ambient 0.35
    diffuse 0.65
    }
  }