/*
 
 t_coil_example.pov
 
 The t_coil macro constructs a helix from sect-
 ions of tori. The goal is to have a relatively
 fast-rendering, easy-to-use coil for general-
 purpose modeling. I optimized the routines, so
 the parsing is very snappy (POV hardly blinked
 at 1000 turns).
 
 There are two versions: regular and solid. The
 solid version can be used in CSG operations,
 but will render much more slowly than the reg-
 ular version. To model a bolt or auger, you
 could use t_coil_solid to cut grooves into a
 cylinder.
 
 The regular version can be used with transpar-
 ency and media without any problems.
 
 Its invocation is like a mix between a cylinder
 and a torus. The result will follow a cylinder,
 with the minor radius extending from the major
 radius.
 
 The macros:
 
 t_coil( ptA, ptB, rad1, rad2, nwnd )
 
 t_coil_solid( ptA, ptB, rad1, rad2, nwnd )
 
  * ptA  = starting point
  * ptB  = ending point
  * rad1 = major radius
  * rad2 = minor radius, the wire's width
  * nwnd = number of windings
 
 Since the object is constructed from torus
 sections, it will not match up with a geo-
 metrically accurate helix. In most cases, it
 would not really matter.
 
*/


// example

#include "t_coil.inc"

object{

 t_coil( <0,-1,0>, <0,1,0>, 0.5, 0.05, 5 )

 pigment{rgb x}

}

// ~example


camera{
 location <3,8,-10>
 look_at 0
 angle 17
}

light_source{
 <.5,1,-.3>*100000,
 1.5
}

plane{ y, -1.05
 pigment{
  checker rgb .85, rgb 1
  translate .5 scale .5
 }
}