//   A disk that can be used as background for the DCC abbacus.
//  
//  Assumes defined
//  
//    base_texture = texture for disk
//    
//  Defines
//  
//    base_disk_thickness = thickness of disk
//    base_disk_radius = disk radius
//  
//    abacus_base = the disk

#declare abacus_base = 
  cylinder {
    <0.0, -base_disk_thickness, 0.0>,
    <0.0, 0.0, 0.0>,
    base_disk_radius
    texture{base_texture}
  }