//  Snakey Mass with 3-Way Rotational Symmetry 
//   (C) Fergus C. Murray, June 2000

#version 3.0
global_settings { assumed_gamma 1.0 }

camera
{
  location  < 0, 0, -30>
  direction  1*z
  look_at   < 0, 0, 0>
}


// ------------------------------------------------------------------
// Simple background for a simple scene
background { color rgb <0.0, 0.0, 0.0> }

// ------------------------------------------------------------------
// A light source
light_source { <50, 20, -50> color rgb 1 }
light_source { <0, 0, -40> color rgb <1,0.7,0.4> }

// ------------------------------------------------------------------
#declare BasicShape =
// create a three-sphere shape
union{
sphere {  x*2,  0.25    rotate (z)  }            
sphere {  x*2,  0.25    rotate (z)*120  }             
sphere {  x*2,  0.25    rotate (z)*240  }           
}

// ------------------------------------------------------------------
// Set up the loop variables:
// the Counter variable will go from 0.0 to 1.0
// in NumIterations loops.
#declare NumIterations = 720 // try different numbers of objects (20,40,80...)
// probably best not change these
#declare Counter       = 0.0
#declare Increment     = 1.0/NumIterations
#declare Arm           = 1
#declare armangle      = 0.0
#declare NumTwists     = 360*4 // full twists

// ------------------------------------------------------------------
// Create an iterated object built from our basic shape
union{
  #declare Flipper = 1  // Flipper will switch between 1 and -1 each loop
  #while (Counter<1.0)
    object
    {
      BasicShape
      scale 1+Flipper*(Counter-0.5)
      //rotate y*Counter*2 
      rotate x*(Flipper*clock-Counter*2)*360
      //rotate z*Counter*360-clock*360
      translate z*2
      rotate 18*cos((Counter*2+Flipper*clock)*pi*2)*x
   //   rotate 30*cos((Counter*2*Flipper-clock)*pi*2)*y      //rotate x*(NumTwists*Counter)
      translate <12*(Counter), 0, 0>
      rotate armangle*z 
       #declare armangle=armangle+60
       // put down the texture
      texture
      {
        pigment
        {
          // colors change as we stack them up
          color rgb <0, (Flipper+1)*sqrt(Counter)*0.2, 0.5-0.5*cos(Counter*1440)>
        }
        finish { ambient 0.01 specular 0.5 diffuse 0.5 roughness 0.1 }
      }
    }
    #declare Flipper = - Flipper // flip its value (1->-1 or -1->1)
    // manually increment our counter inside the loop
    #declare Counter=Counter+Increment
  #end
}