"Sun Tzu" <sun### [at] nospamhotmailcom> wrote in
news:3ec983aa@news.povray.org: 

> I was inspired by an image posted here (I wish I could remember the
> author's name), and decided to make my first macro to generate a
> similar shape.  I couldn't figure out how to do this shape with just
> Tori and Sphere CSG, and had to use a Cone as well.  Unfortunately the
> 'seams' are visible where the spheres are cut out and join with the
> tori.  Is this an inherent problem with POV accuracy and rounding
> errors, or is there a flaw in my math?  More importantly, is there a
> way to fix it?  I will attach my source as well as the picture. 
> 
> Also the opening on the far side of the sphere doesn't seem to show up
> in this view, but I've checked with a top down view and it is
> definitely there.  Maybe it's just the angle. 
...

I think the author of the image you refer to is me:
http://news.povray.org/povray.binaries.images/31443/
(Your approcah to make such a shape is somewhat different from mine.)


You can get rid of the "seems" if you add these lines to you macro:

#local rnil = r1*1e-6;
#local cutconebigger =
  cone {<0,0,0>,0, <0,r1+1,0>,(r1+1)*tan(asin((hole+r2)/(r1-r2))) + rnil}

- and replace "cutcone" with "cutconebigger" in the 4 intersection
statements that are similar to this:

intersection {
  difference {
    object{ torus_os ... }
    object{ torus_is ... }
  }
  object { cutcone ... }
}


When merging objects, the objects should "overlap" each other slightly.


Btw.: Your macro can be improved. (I can post my suggestion if you like.)


Tor Olav

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