thanks, we've gotten some basic knowledge on the isosurfaces now.
    the problem is, they're only surfaces, not solid figures with a certain
width, so we're wondering if there is a way to, e.g., extrude a parabola 2
units, making it solid? that would've been smooth, he he. or do you see some
other way?

(sorry about the double posting with binary attached, first, i was about to
post in a .binaries group, but i found out that i
didnt need the image, so i posted here instead. however, i forgot to remove
the image. sheesh. =) )

- lars petter

"Hughes, B." <omn### [at] charternet> wrote in message
news:40316c8c$1@news.povray.org...
> "lars petter" <lar### [at] higno> wrote in message
> news:4030e7fc$1@news.povray.org...
> > I'll try again.. (sorry for any inclarities, i dont exactly know what
i'm
> > asking for :) )
>
> I've seen your original message post at the programming group.
>
> > The view in the tool will be in the x,y plane, viewed from top.. in the
> > "drawing board" they will place differented shapes suchs as bezier
curves,
> > parabolas, circles (closed, open), ellipes (closed, open), and so on.
> these
> > shapes will have user-specific properties regarding to absorption,
> > diffusion, width, and color. After placing a light source, we want to
> render
> > the scene in povray. The main point is to illustrate the caustics
> generated
> > by the system of mirrors in the scene..
>
> So you'll be using photons, no doubt.
>
> > Anyway, we've looked at the documentation, and tested a little "coding",
> and
> > concluded with that we probably should use the prism object to generate
> the
> > pov-ray figures, at least the bezier shapes.
>
> You could be right about that. Not real sure myself.
>
> > We've also looked at the various internal/math/whatever-functions in the
> > .inc files, but we really cant understand how we actually use these to
get
> > shapes into the scene.. i'm looking at:
> > Quartic_Paraboloid
> > Quartic parabola - a 4th degree polynomial (has two bumps at the bottom)
> > that has been swept around the z axis. The equation is:
> > 0.1 x^4 - x^2 - y^2 - z^2 + 0.9 = 0
> >
> > how do i use this?
> >
> > all in all, we do have the mathematical parametres from the 2d-plane,
and
> > what we're looking for is some easy way to apply these to generate the
3d
> > figures..
>
> Isosurfaces seem the most plausible thing to me, since you'll be working
> with equations anyhow. I've taken the example for f_quartic_paraboloid()
> from the scenes\incdemo\i_internal.inc to make:
>
> camera {
>   location  <0.0, 0.0, -5.0>
>   look_at   <0.0, 0.0, 0.0>
> }
>
> sky_sphere {
>   pigment {
>     gradient y
>     color_map {
>       [0 rgb <0.9,0.9,0.9>]
>       [1 rgb <0.3,0.3,0.3>]
>     }
>   }
> }
>
> light_source {
>  -100*z,
>  color rgb <1, 1, 1>
>   rotate <15, 15, 0>
> }
>
> // ----------------------------------------
>
> #include "functions.inc"
>
> #declare IsoQP=
> isosurface {
>  function  {
>   // f_quartic_paraboloid(x,y,z, -0.01)
>   0-(0.5*x*x*x*x-x*x-y*y-z*z+0.5)
>  }
>  // contained_by {box { <-1.45, -0.1, -1.45>, <1.45, 2.5, 1.45> }}
>  max_gradient 2.5
>  all_intersections
> }
>
> difference {
> object { // outside
>     IsoQP
>     material {
>      texture {
>       pigment {color rgb 0.75}
>       finish {reflection {0.3,0.9}}
>      }
>     }
> }
> object { // inside
>     IsoQP
>     scale <0.95,0.95,0.95>
>     translate y/6
>     material {
>      texture {
>       pigment {color rgb 0.25}
>       finish {reflection {0.1,0.3}}
>      }
>     }
> }
> // rotate -90*x // turn to look into parabloid
> }
>
> Maybe you can figure something out from this and by reading up on
isosurface
> functions. I'm not very good at the math, and you should be warned that
the
> carat (^) sign is not used in POV-Ray. If you'll be needing
semitransparent
> materials, the above texturing won't suffice to blend from one side to the
> other.
>
> Bob H.
>
>

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