"yesbird" <nomail@nomail> wrote:
> Hi,
>
> Can anybody explain me, please, how 'isosurface' works ?
> I am trying to render:
>
> V = cos(x) + cos(y) + cos(z); // Attached

So, IIRC that's like a gyroid or something...

If you email me, I can can send you a PDF copy of Mike Williams' Isosurface
Tutorial.

But the key idea is that it's an ISOsurface.

Very often what you need to do is subtract your function result from a space
coordinate so that when the function's surface point is AT that space point, the
result is zero - or whatever you set your threshold to.

After a few quick experiments, I established that you like want to "check" the
distance of your curve from a sphere, so I used that.  You can probably use the
in-built f_sphere as well.


So try:

camp (7,0,-7, 0,0.3,0, 55)


//-------------  Objects --------------------------------------------

//
// FUnction
//
// #declare f = function { f_sphere(x,y,z,0.8) - pow(f_noise3d(x,y,z),2) } // Ok
#declare f = function { cos(x) + cos(y) + cos(z) } // Not displayed (?)

//
// Surface
//
#declare R = 1;
isosurface {
  function { sqrt (x*x+y*y+z*z)/8 - f(x, y, z)}

   threshold 0
 accuracy 0.0001
 max_gradient 1.6
 open
 contained_by {box {-4, +4}}

  pigment { rgbft <0,0.5,0,0.6,0>
            scale 2
            translate 1}

}

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