Wasn't it James Taylor who wrote:
>Hi all,
>
>Whats the easiest way of making a spiral which follows the surface of a
>cylinder. The only way I can see is to sweep lots of boxes through the
>spiral. ie like a sphere_sweep but with a rectangular cross section.
>
>Thanks
>jim
>-is there an isosurface solution? - although I have a slow computer and the
>scene will be rendered with radiosity which may make the render time
>unacceptably long :(

Set the "cross section type" parameter of the f_helix1() function to 2
(diamond shape) and then set the cross section rotation angle to 45.
(They're the last two parameters of f_helix1().)

For example:-

#include "functions.inc"

camera { location  <0, 2, -2> look_at 0}

background {rgb 1}

light_source {<-10,20,-10> colour rgb 1}

isosurface {
  function { f_helix1(x,y,z,2,5,0.1,0.3,3,2,45) }
  max_gradient 1.5
  contained_by{box {<-0.4,-2,-0.4> <0.4,1,0.4>}}
  pigment {rgb 1}
}

Post a reply to this message