/*************************************************************************
COIL GENERATOR INCLUDE FILE FOR PERSISTENCE OF VISION 3.x
**************************************************************************
Created by Chris Colefax, 15 October 1997
Updated 18 July 1998: updated for POV-Ray 3.1
OVERVIEW: Creates a coil (helix) object between any two points.
USAGE: First specify the two points you wish to connect with the coil, eg:
#declare coil_point1 = <0, 0, 0>;
#declare coil_point2 = <0, 10, 0>;
Then include this file within an object {} statement, adding any
textures, transformations, etc. you want:
object {#include "Coil.inc"
texture {MyTexture}
rotate y * clock * 360}
You can use the coils in CSG objects, or declare them and reuse them.
OPTIONS: In addition to the two coil points, you can use the following
options to modify the coil:
-- OPTION ------- DEFAULT -- DESCRIPTION ---------------------------
coil_type 3 Sets the style of the coil
(choose from 1, 2, or 3)
coil_radius 2 Sets the radius of the coil at point1
coil_radius2 2 Sets the radius of the coil at point2
coil_thickness 0.2 Sets the thickness of the coil at point1
coil_thickness2 0.2 Sets the thickness of the coil at point2
coil_revolutions 5 Sets the number of revolutions in the coil
coil_smoothness 36 Sets the smoothness of coil types 1 and 2
Setting coil_type to 1 uses spheres to create the coil (which may be
non-continuous). Setting coil_type to 2 joins the spheres with
cylinders, creating a continuous coil. Setting coil_type to 3 uses
half-torii sections, which is usually smoother and takes up less memory
than types 1 and 2 (although it's not always as accurate, especially when
animating the coil). You can set the number of spheres and/or cylinders
used for types 1 and 2 by changing the coil_smoothness option (which sets
the number of objects used *per revolution*).
If you do not specify coil_radius2 and/or coil_thickness2 they will be
the same as coil_radius and coil_thickness, ie. you only need to specify
them when you want to create a conical coil.
Setting coil_revolutions to a positive number creates a clockwise coil;
setting coil_revolutions to a negative number creates an anti-clockwise
coil. Note that you can only use revolution multiples of .5 if you
are using coil_type 3, eg: coil_revolutions = 1.7 is truncated to 1.5
*************************************************************************/
// CHECK REQUIRED PARAMETERS AND ASSIGN DEFAULTS
// *********************************************
#declare _CG_tempver = version; #version 3.0;
#ifndef (coil_point1) #declare _CG_point1 = <0, 0, 0>; #else #declare _CG_point1 = <1, 1, 1> * coil_point1; #end
#ifndef (coil_point2) #declare _CG_point2 = _CG_point1 + <0, 10, 0>; #else #declare _CG_point2 = <1, 1, 1> * coil_point2; #end
#ifndef (coil_radius) #declare coil_radius = 2; #end
#ifndef (coil_radius2) #declare coil_radius2 = coil_radius; #end
#ifndef (coil_thickness) #declare coil_thickness = .2; #end
#ifndef (coil_thickness2) #declare coil_thickness2 = coil_thickness; #end
#ifndef (coil_revolutions) #declare _CG_revs = 5; #else #declare _CG_revs = coil_revolutions; #end
#ifndef (coil_smoothness) #declare coil_smoothness = 36; #end
#ifndef (coil_type) #declare coil_type = 3; #end
// CALC COIL POSITIONING VALUES
// ****************************
#declare _CG_axis = _CG_point2 - _CG_point1;
#declare _CG_length = vlength(_CG_axis);
#declare _CG_rotx = vlength(_CG_axis * <1, 0, 1>); #if (_CG_rotx != 0 | _CG_axis.y != 0) #declare _CG_rotx = degrees(atan2(vlength(_CG_axis * <1, 0, 1>), _CG_axis.y)); #end
#declare _CG_roty = _CG_axis.x; #if (_CG_roty != 0 | _CG_axis.z != 0) #declare _CG_roty = degrees(atan2(_CG_axis.x, _CG_axis.z)); #end
#if (_CG_revs = 0) #declare _CG_revs = 1; #end
#if (_CG_revs < 0) #declare _CG_revs = abs(_CG_revs); #declare _CG_flip = -1; #else #declare _CG_flip = 1; #end
// CREATE COIL
// ***********
union { #switch (coil_type)
// CREATE COIL FROM SPHERES
// ************************
#case (1)
#declare _CG_heightint = _CG_length / (_CG_revs * coil_smoothness);
#declare _CG_height = 0; #while (_CG_height <= _CG_length)
#declare _CG_curpos = _CG_height / _CG_length;
sphere {,
coil_thickness + (_CG_curpos * (coil_thickness2 - coil_thickness))
rotate y * _CG_curpos * 360 * _CG_revs}
#declare _CG_height = _CG_height + _CG_heightint; #end
#break
// CREATE COIL FROM SPHERES AND CYLINDERS
// **************************************
#case (2)
#declare _CG_heightint = _CG_length / (_CG_revs * coil_smoothness);
#declare _CG_height = 0; #while (_CG_height <= _CG_length)
#declare _CG_curpos = _CG_height / _CG_length;
#if (_CG_height > 0)
#declare _CG_oldpoint = _CG_curpoint;
#declare _CG_oldradius = _CG_curradius;
#end
#declare _CG_curpoint = vrotate (
,
y * _CG_curpos * 360 * _CG_revs)
#declare _CG_curradius = coil_thickness + (_CG_curpos * (coil_thickness2 - coil_thickness));
sphere {_CG_curpoint, _CG_curradius}
#if (_CG_height > 0) cylinder {_CG_oldpoint, _CG_curpoint, _CG_oldradius} #end
#declare _CG_height = _CG_height + _CG_heightint; #end
#break
// CREATE COIL FROM TORII SECTIONS
// *******************************
#else
#declare _CG_height = 0; #while (_CG_height <= _CG_revs * 2)
#declare _CG_curpos = _CG_height / (_CG_revs * 2);
#if (_CG_height > 0)
#declare _CG_oldpoint = _CG_curpoint;
#declare _CG_oldradius = _CG_curradius;
#end
#declare _CG_curpoint = vrotate (
,
y * _CG_curpos * 360 * _CG_revs);
#declare _CG_curradius = coil_thickness + (_CG_curpos * (coil_thickness2 - coil_thickness));
#if (_CG_height = 0)
sphere {_CG_curpoint, _CG_curradius}
#else
sphere {_CG_curpoint, _CG_oldradius}
#declare _CG_toraxis = _CG_curpoint - _CG_oldpoint;
#declare _CG_torradius = vlength(_CG_toraxis) / 2;
intersection {
torus {_CG_torradius, _CG_oldradius}
box {<-(_CG_torradius + _CG_oldradius), -_CG_oldradius, -(_CG_torradius + _CG_oldradius)>,
<(_CG_torradius + _CG_oldradius), _CG_oldradius, 0>
#if (mod(_CG_height, 2) = 0) scale <1, 1, -1> #end
}
translate x * _CG_torradius
rotate z * degrees(atan2(_CG_toraxis.y, _CG_toraxis.x))
translate _CG_oldpoint}
#end
#declare _CG_height = _CG_height + 1; #end
#end
// POSITION COIL
// *************
scale <1, 1, _CG_flip>
rotate <_CG_rotx, _CG_roty, 0>
translate _CG_point1}
#version _CG_tempver;
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