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[Oleg <(005b7a4cd6%hidden_head%005b7a4cd6)olegs(005b7a4cd6%hidden_at%005b7a4cd6)mosk.ru(005b7a4cd6%hidden_end%005b7a4cd6)>]

Hello everyone! I'm trying to use a combination of implicit functions to
create cone, cylinder, cube, and other surfaces for subsequent
triangulation. I'm taking 
http://www.cgal.org/Manual/latest/examples/Surface_mesher/mesh_an_implicit_function.cpp
mesh_an_implicit_function.cpp  and 
http://www.cgal.org/Manual/latest/examples/Mesh_3/mesh_two_implicit_spheres_with_balls.cpp
mesh_two_implicit_spheres_with_balls.cpp  examples as the starting point and
trying to apply them to my case. Having tried a few variants I've come up
with the following code for the cone function:

FT cone_function (Point_3 p) {
  const FT x2=p.x()*p.x(), y2=p.y()*p.y(), z2=p.z()*p.z();
  const FT z1=p.z();
  if( z1<=1 && z1>=0 )
        return x2+y2-z2;
  else if( z1==1 )
        return z2-1;
  else
        return 1;
}

It does produce a cone surface, automatically cutting off the part of z2-1
plane exceeding the cone. So, I'd suppose that the following code should
also work:

FT cone_function1 (Point_3 p) {
  const FT x2=p.x()*p.x(), y2=p.y()*p.y(), z2=p.z()*p.z();
  return x2+y2-z2;
}

FT cone_function2 (Point_3 p) {
  const FT z2=p.z();
  return z2-1;
}

FT cone_function (Point_3 p) {
  if(cone_function1(p)==0 || cone_function2(p)==0)
          return 0;
  else
          return 1;
}

but it produces an invalid .off file. What would be the general guidelines
for using implicit functions for creating complex shapes? E.g., what would
be the best way to define a cube surface? Appreciate any help.


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