// system :  Win98 / Athlon 800 / 512 MHz RAM  / beta10
// A rare prism bug: Following code produced strange behavior of 
illumination/texture of conic prisms.
// If one declares a rotation value smaller than -89.999999994270432
// and bigger -90.0000000057296  the conic sides of the prism are not 
illuminated by the light_source,
// with ambient 1 they are visible. this happens to all spline types (at 
least the examples I tested).  
// (if  necassary, I can post 2 sample render pictures)
//
// 8) SciBorg
// good luck !


#version 3.5
#declare test=texture { pigment { color rgb 1  } finish { ambient 0  
diffuse 1}   }
light_source {  0*x  color rgb 1.0 translate <10, 10, 50> }
camera {  orthographic  location <0,0,4> look_at  <0,0,0>  right 2.1*x  
up 2.1*y  }
// ----------------------------------------
prism {                                
  conic_sweep  // linear_sweep or conic_sweep for tapering to a point
  linear_spline // linear_spline | quadratic_spline | cubic_spline | 
bezier_spline
  1,  0.5,   4, <-1, -1>,< 1, -1>,<1, 1>,<-1,  1>    
  //rotate  -90.0000000057296*x     // visible
  //rotate  -90.0000000057295*x     // invisible
  rotate  -90*x                   // invisible
  //rotate  -89.999999994270433*x   // invisible
  //rotate  -89.999999994270432*x   // visible
  texture { test }  
}

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