Only problem is isosurfaces are a lot slower and can get artefacts more often...

- Nekar

"Mike Williams" <mik### [at] nospamplease> wrote in message
news:Axy### [at] econymdemoncouk...
> Wasn't it TAlphaBravo who wrote:
>
> >What I wanna see is a blob object that can model any of the primatives into
> >a blob, I know of times when this would be a Godsend!
>
> Most of the POV primitives can be represented by isosurfaces. It's
> possible to blob isosurfaces together (see below) in both POV 3.5 and
> MegaPOV. The following classes of primitives that can't (easily) be
> represented by isosurfaces:-
>
> 1. Some Finite Patch Primitives: Bicubic patch, mesh, mesh2 and
> smooth_triangle. The other finite patch primitives (polygon, disc,
> triangle) can be easily represented as flat isosurfaces that have a
> small thickness. It could well be argued that the concept of blobbing
> finite patches is not meaningful.
>
> 2. Julia_Fractal
>
> 3. Text
>
> 4. Sphere_Sweep
>
> Any other primitives can be easily represented by isosurfaces and then
> blobbed.
>
> From <http://www.econym.demon.co.uk/isotut/combine.htm>
>
>   Blob-like combinations
>   ======================
>
>   #include "functions.inc"
>   #declare  S = function {f_sphere(x,y,z,0.5)}
>   #declare  T = function {f_torus(x,y,z,1,0.2)}
>
>   isosurface {
>     function { S(x-0.7,y,z) * T(x,y,z) - 0.05}
>          max_gradient 2
>          accuracy 0.001
>          contained_by{sphere{0,R}}
>          pigment {rgb .9}
>   }
>
>   [The MegaPOV syntax for the sphere and torus built in functions is ]
>   [#declare S = function {"sphere" <.5>}                             ]
>   [#declare T = function {"torus" <1,0.2>}                           ]
>
>   Multiplying surfaces then adding a small constant produces an effect
>   that's similar to using blobs. However, this technique can be used to
>   blob together any kind of isosurface, not just spheres and cylinders.
>
>
> Also, in MegaPOV, it's possible to perform isosurface blobbing of any
> object by creating the isosurfaces from proximity patterns of the
> objects. Proximity patterns are not available in POV3.5. MegaPOV
> proximity patterns are rather slow.
>
> --
> Mike Williams
> Gentleman of Leisure


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