"Shurakai" <nomail@nomail> wrote:
> "Akuma" <afr### [at] hotmailcom> wrote:
> > I've been trying to create a strand of DNA using an isosurface. However, I
> > keep having trouble creating the double helix using the function f_helix1
> > found in functions.inc
> >
> > Could anybody give me an example double helix for me to start with? It'd be
> > a big help.
>
> There's a DNA strand included in the CrystalPOV scene template package. I
> took the strand from Accelrys DS. In this program there's also a structure
> data file included from a DNA strand. You can use several molecular
> structure visualization programs to convert this data into a pov-ray scene
> file. If You should not find it, i can send You the pov file.
>
> Shu

I had been thinking about creating a DNA backbone with POVray for quite a
while. With some of the information on here I came up with this that works
very nicely:

#include "functions.inc"
#include "colors.inc"

camera {
  location  <0, 0, 50>
  look_at   <0, 0.0,  0.0> }

light_source { <00,0,100> colour rgb 1 }
background { rgb <0,0,0> }

#declare double = union {
isosurface {
function {  f_helix1 (x,y,z,1,1,0.5,2,1,1,-180) }
        max_gradient 2
        contained_by {sphere {1, 20} }
        pigment {rgb <1,1,1>}
           }

isosurface {
function {  f_helix1 (x,y,z,1,1,0.5,2,1,1,-180) }
        max_gradient 2
        contained_by {sphere {1, 20} }
        pigment {rgb <1,1,1>
        }
        rotate <0,120,0>
           }
}

object {
double
}

There is one MAJOR problem. This makes a left-handed helix. DNA should be
right-handed. Does anyone know how to change this?

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